jueves, 31 de mayo de 2012

On early Earth, iron may have performed magnesium's RNA folding job

ORIGINAL: eScienceNews
May 31, 2012
Loren Williams, professor in the Georgia Tech School of Chemistry and Biochemistry, used experiments and numerical calculations to show that in plausible early earth conditions, iron can substitute for magnesium in RNA binding, folding and catalysis. Georgia Tech/Gary Meek.
Jessica Bowman (left) and Loren Williams from the Georgia Tech School of Chemistry and Biochemistry assess a gel showing that RNA is not degraded by iron if oxygen is omitted. Based on these results, Williams hypothesizes that RNA evolved on the early earth in the presence of iron and is optimized to work with iron. Georgia Tech/Gary Meek.
Georgia Tech biology postdoctoral fellow Shreyas Athavale (left) and chemistry and biochemistry professor Loren Williams look at a gel showing the products of a ribozyme reaction that was run with iron instead of magnesium. Under identical anaerobic conditions, the activity of two enzymes was enhanced in the presence of iron, compared to their activity in the presence of magnesium . Georgia Tech/Gary Meek  .

On the periodic table of the elements, iron and magnesium are far apart. But new evidence suggests that 3 billion years ago, iron did the chemical work now done by magnesium in helping RNA fold and function properly. There is considerable evidence that the evolution of life passed through an early stage when RNA played a more central role before DNA and coded proteins appeared. During that time, more than 3 billion years ago, the environment lacked oxygen but had an abundance of soluble iron.

In a new study, researchers from the Georgia Institute of Technology used experiments and numerical calculations to show that iron, in the absence of oxygen, can substitute for magnesium in RNA binding, folding and catalysis. The researchers found that RNA's shape and folding structure remained the same and its functional activity increased when magnesium was replaced by iron in an oxygen-free environment.

"The primary motivation of this work was to understand RNA in plausible early earth conditions and we found that iron could support an array of RNA structures and catalytic functions more diverse than RNA with magnesium," said Loren Williams, a professor in the School of Chemistry and Biochemistry at Georgia Tech.

The results of the study were published online on May 31, 2012 in the journal PLoS ONE. The study was supported by the NASA Astrobiology Institute.

In addition to Williams, Georgia Tech School of Biology postdoctoral fellow Shreyas Athavale, research scientist Anton Petrov, and professors Roger Wartell and Stephen Harvey, and Georgia Tech School of Chemistry and Biochemistry postdoctoral fellow Chiaolong Hsiao and professor Nicholas Hud also contributed to this work.

Free oxygen gas was almost nonexistent more than 3 billion years ago in the early earth's atmosphere. When oxygen began entering the environment as a product of photosynthesis, it turned the earth's iron to rust, forming massive banded iron formations that are still mined today. The free oxygen produced by advanced organisms caused iron to be toxic, even though it was -- and still is -- a requirement for life.

This environmental transition triggered by the introduction of free oxygen into the atmosphere would have caused a slow, but dramatic, shift in biology that required transformations in biochemical mechanisms and metabolic pathways. The current study provides evidence that this transition may have caused a shift from iron to magnesium for RNA binding, folding and catalysis processes.

The researchers used quantum mechanical calculations, chemical footprinting and two ribozyme assays to determine that in an oxygen-free environment, iron, Fe2+, can be substituted for magnesium, Mg2+, in RNA folding and catalysis.

Quantum mechanical calculations showed that the structure of RNA was nearly identical when it included iron or magnesium. When large RNAs fold into native, stable structures, negatively charged phosphate groups are brought into close proximity. The researchers calculated one small difference between the activity of iron and magnesium structures: more charge was transferred from phosphate to iron than from phosphate to magnesium.

Chemical probing under anaerobic conditions showed that iron could replace magnesium in compacting and folding large RNA structures, thus providing evidence that iron and magnesium could be nearly interchangeable in their interactions with RNA.

Under identical anaerobic conditions, the activity of two enzymes was enhanced in the presence of iron, compared to their activity in the presence of magnesium. The initial activity of the L1 ribozyme ligase, an enzyme that glues together pieces of RNA, was 25 times higher in the presence of iron. Activity of the hammerhead ribozyme, an enzyme that cuts RNA, was three times higher in the presence of iron compared to magnesium.

"The results suggest that iron is a superior substitute for magnesium in these catalytic roles," said Williams, who is also director of the Center for Ribosomal Origins and Evolution at Georgia Tech. "Our hypothesis is that RNA evolved in the presence of iron and is optimized to work with iron."

In future studies, the researchers plan to investigate what unique functions RNA can possess with iron that are not possible with magnesium.

Ink injection reveals chick embryo's beating heart

ORIGINAL: New Scientist
February 2012
Sandrine Ceurstemont, editor, New Scientist TV

Like a living work of art, a chick embryo's beating heart and intricate pattern of blood vessels are exposed as it's injected with ink under a microscope. Captured by biologist Anna Franz from the University of Oxford as she attempted the technique for the first time, the video has just won first place in the Nikon Small World Photomicrography Competition.

The movie shows how blood vessels inside and outside the embryo are connected, as well as revealing the direction of blood flow through arteries and veins. The technique is often used by researchers to visualise how nutrients and oxygen are transported to an embryo and to study how a heart functions and develops.

According to Franz, the procedure was relatively quick and easy to perform. A window was first cut into the egg to expose the 72 hour-old embryo before it was placed under a microscope. Then a capillary needle was carefully inserted into an artery in the yolk sac, releasing ink throughout the network of blood vessels.

The technique gives insight into both chick and human circulatory systems since they are very similar. "An increased understanding of the development and function of the heart and blood vessels can help to discover novel ways of healing wounds and treating cancer and cardiovascular diseases," says Franz.

Logran secuencia del genoma del tomate



Video Original:UPV-TV

Un proyecto en el que participan investigadores de la UPV es hoy portada en la revista Nature. Su logro ha sido secuenciar el ADN del tomate, lo que permitirá mejorar la calidad de los mismos. Esperamos que, a partir de ahora, no sea tan difícil encontrar tomates con todo su sabor.


Tomato genome sequence bears fruit
30 May 2012

Work paves way for high-yield crops with good flavour.
Tomatos have twice triplicated their genome in the past hundred million years. NIK MERKULOV / SHUTTERSTOCK

The genome sequence of one of the world’s highest-value salad plants — the tomato — has been decoded by an international team of scientists, and is published today in Nature1 .

The tomato (Solanum lycopersicum) is an increasingly popular fruit, with 145.8 million tonnes produced globally in 2010.

According to the leaders of the UK arm of the Tomato Genome Consortium, Graham Seymour at the University of Nottingham and Gerard Bishop, formerly of Imperial College London, the sequence will make precision breeding possible not just in tomatoes, but also in other crop species from the Solanaceae family, such as aubergines (Solanum melongena) and peppers (Capsicum spp.).

They also hope it will help in the development of tomatoes that can survive pests, pathogens and even climate change, as well as high-yield crops that still have a good flavour. “It’s really all about making a better tomato,” says Allen Van Deynze, a molecular geneticist at the Seed Biotechnology Center at the University of California, Davis. “This work enables a lot of things we just couldn’t do before.”

Launched in 2003, the project has taken some time to get results, but it has produced an “amazingly complete” sequence, the leaders say. With more than 80% of the genome sequenced, and more than 90% of the genes within it identified, and refinements still taking place, the group hopes to make this a gold-standard reference sequence. "It's one of the better genomes out there," says Van Deynze.

Evolving tactics
Giovanni Giuliano, from the Italian National Agency for New Technologies, Energy and Sustainable Economic Development in Rome, and a lead researcher on the project, explains that the group started out using traditional tools to sequence the genomes of the domesticated tomato cultivar Heinz 1706 (the one used to make the famous ketchup) and its closest wild relative, Solanum pimpinellifolium.

However, when the data still had major holes by 2008, the team took advantage of ‘next-generation’ technologies and switched to the much faster method of whole-genome shotgun sequencing. In this technique, large chunks of DNA are sequenced separately, pieced back together, then assembled into the genome.

Giuliano says that one of the most exciting discoveries was that the entire tomato genome was copied in triplicate on two separate occasions. The earlier event occurred about 130 million years ago, and was first identified in grapes (Vitis vinifera)2, but what interests Giuliano is that a second event occurred around 60 million years ago, and had major implications for the development of the fruit.

“Several of the genes ‘born’ at that second triplication stayed in the genome for tens of millions of years,” he says. “Then, relatively recently, they changed their function — this brought about the appearance of the fleshy fruit as we know it today.” The tomato is already an established model for fleshy fruit development, so the information will also be useful for breeding fruits such as strawberries, melons and bananas.

“The next thing,” says Johnathan Napier, a plant biotechnologist at Rothamsted Research in Harpenden, UK, “is to link this genome sequence to traits that are useful and important, especially for food security and human health.”

Robotic Rehab Helps Paralyzed Rats Walk Again

ORIGINAL: Science Magazine
by Greg Miller on 31 May 2012, 2:06 PM 

Reanimated. In a new study, robot-assisted rehabilitation helped paralyzed rats regain use of their legs. Credit: Courtesy of EPFL. Lausanne, Switzerland
By employing a combination of drugs, electrical stimulation, and robot-assisted rehabilitation, researchers have restored a remarkable degree of voluntary movement in rats paralyzed by a spinal cord injury. After several weeks of treatment, the rodents were able to walk—with some assistance—to retrieve a piece of food, even going up stairs or climbing over a small barrier to get it. The rats' recovery raises hopes that a similar combination strategy could help restore movement in some people with spinal injuries. Indeed, such efforts are already underway.

Spinal injuries cause paralysis because they sever or crush nerve fibers that connect the brain to neurons in the spinal cord that move muscles throughout the body. These fibers, or axons, are the long extensions that convey signals from one end of a neuron to another, and unfortunately, they don't regrow in adults. That's why paralysis from a spinal injury is a lifelong disability. Restoring axons' ability to regrow using growth factors, stem cells, or other therapies has been a longstanding—but frustratingly elusive—goal for researchers.

The new study, which appears in Science today, takes a different approach. Instead of trying to repair the main information superhighway from the brain to the body, Grégoire Courtine, of the Swiss Federal Institute of Technology in Lausanne, and colleagues focused on alternative routes. Most spinal injuries in people do not sever the spinal cord completely, explains Courtine. To approximate this situation in rats, his team made two surgical cuts in the spinal cord, severing all of the direct connections from the brain, but leaving some tissue intact in between the cuts. Then they had the rodents begin a rehab regime intended to bypass the fractured freeway, as it were, by pushing more traffic onto neural back roads and building more of them.

This regime, which began about a week after the rats were injured, lasted about 30 minutes a day. During each session, the researchers injected the animals with a cocktail of drugs to improve the function of rats' neural circuits in the part of the spinal cord involved in leg movements, and they stimulated this area with electrodes. With its spinal cord thus primed for action, a rat was fitted into a harness attached to a robotic device that supported its weight and allowed it to walk forward on its hind legs to the extent that it was able. At first, the rats could not move their legs at all, let alone walk.

But after 2 or 3 weeks, the rodents began taking steps toward a piece of food after a gentle nudge from the robot. By 5 or 6 weeks, they were able to initiate movement on their own and walk to get the food. And after a few additional weeks of intensified rehab, they were able to walk up rat-sized stairs and climb over a small barrier placed in their path. Rats that did not undergo rehab, in contrast, showed no improvement at all. Rats suspended over a moving treadmill that elicited reflex-like stepping movement, did not improve either, suggesting that full recovery depends on making intentional movements, not just any movement.

"It's a really remarkable finding," says Michael Beattie, a neuroscientist at the Brain and Spinal Injury Center at the University of California, San Francisco. Additional experiments in the paper make a compelling case that the rats' recovery is due to new neural connections forming to create a detour around the injury, he says. Beattie notes that Courtine's work suggests that all three components of the rehab strategy—the drugs, the electrical stimulation, and the robot-assisted physical therapy—seem to be necessary to maximize recovery. "I think that it actually provides a lot of hope that this kind of strategy will have a big payoff" in people, Beattie concludes.

A case study published last year reported some recovery of voluntary movements in a man paralyzed in a vehicle accident, after he underwent a combination of electrical stimulation and physical therapy. The new rodent research provides a potential explanation for that patient's recovery, says one of the lead authors of the case study, neuroscientist V. Reggie Edgerton at the University of California, Los Angeles. Edgerton says two more patients are undergoing similar rehab now, and his group hopes to add drug therapy to enhance nerve repair in the future. "We're not there yet," he says. "But the bottom line is, things are still looking good."

As encouraging as the new findings are, Courtine is careful to note the strategy's limitations
For one thing, it wouldn't work if the spinal cord were completely severed
In addition, treated rats could only make voluntary movements while the electrical stimulation was turned on, and the same was mostly true of the patient Edgerton and colleagues worked with. "This is not a cure for spinal cord injury," Courtine says. "It's a promising proof of principle."

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Nueva máquina para horticultura doméstica en interiores iniciará pruebas en Japón

June 01, 2012 (JP)

Un prototipo de la máquina para cultivar plantas está siendo desarrollado por Panasonic Corp. (Foto proporcionada por Panasonic Corp.)
Panasonic Corp. dijo que se unirá a la Universidad de Chiba y otros grupos para probar una máquina de horticultura que incluso las personas sin habilidad "verde" puede manejar.

La prueba comenzará en pleno en septiembre en una zona de Kashiwa, en la prefectura de Chiba, que ha sido designada una "ciudad inteligente" en virtud de un programa de gobierno.

Cada una de cerca de 10 familias que participan en la prueba recibirán una máquina de cultivo de plantas, de 85 centímetros de alto, 38 cm de largo y 60 cm.

Las máquinas en forma de caja requieren poca mano de obra para cultivar hortalizas y otras plantas, ya que se conectan a un servidor en la universidad para controlar automáticamente la temperatura y la humedad.

Cuando se necesitan riego y otras tareas, la información será facilitada por correo electrónico. Utiliza iluminación LED para el cultivo de las plantas.

Panasonic dijo que la gente puede plantar lechugas, albahaca, fresas y otras plantas, independientemente de las condiciones meteorológicas.

Genes Culled from Desert Soils Suggest Potential Medical Resource

ORIGINAL: Science Daily

ScienceDaily (May 27, 2012) — Despite their ecologic similarity, soils from three geographically distinct areas of the American southwest harbor vastly different collections of small, biosynthetic genes, a finding that suggests the existence of a far greater diversity of potentially useful products than was previously supposed. The research is published in the May issue of Applied and Environmental Microbiology.

Natural compounds have been the sources of the majority of new drugs approved by the US Food and Drug Administration, and bacteria have been the biggest single source of these therapeutically relevant compounds. Most bacterially-derived antibiotic and anticancer agents were discovered by culturing bacteria from environmental samples, and then examining the metabolites they produce in laboratory fermentation studies. But the vast majority of bacterial species cannot be cultured, which suggested that the world might be awash in potentially useful, but unknown bacterial metabolites.

In this study, Sean Brady of the Howard Hughes Medical Institute, Rockefeller University, New York, NY, and colleagues extracted DNA from soils from the Sonoran Desert of Arizona, the Anza Borrego section of the Sonoran Desert of California, and the Great Basin Desert of Utah. They used this DNA to construct very large metagenomic DNA libraries, and screened these libraries for three of the most common classes of small molecule biosynthesis systems,
  • type I modular polyketides
  • type II iterative polyketides, and 
  • non-ribosomal peptides
says Brady.

The investigators used PCR to amplify collections of gene fragments from each of the three libraries and compared these to assess the similarities and differences between the collections of genes cloned from each environment, says Brady.

"Our work suggests that the genomes of environmental bacteria could encode many additional drug-like molecules, including compounds that might serve, among other things, as new antibiotics and anticancer agents," says Brady. "This is a small preliminary study that warrants additional investigations of more environments and more extensive sequence analysis, but it suggests that environmental bacteria have the potential to encode a large additional treasure trove of new medicines."

Chevron CEO tells critics they are wrong

by David R. Baker
May 30, 2012

San Ramon — Chevron Corp. CEO John Watson faced some of his company’s sharpest critics Wednesday during the oil giant’s annual shareholders meeting and politely told them they were wrong.

Wrong about Chevron’s record on environmental protection. Wrong about the company’s impact on the countries where it pumps oil.

And wrong about a high-profile pollution lawsuit in Ecuador that led to an $18 billion judgment against Chevron, a verdict the company continues to fight.

Whatever we do, we’ll do safely or not at all,” Watson told Chevron executives, investors and critics packed into a conference room at the company’s San Ramon headquarters.

Activists who had come from around the world to confront Watson, however, weren’t giving ground.

One castigated Chevron for an explosion in January at a natural gas platform off the coast of Nigeria, a blast that killed two people. Another critic, from Angola, complained about frequent, fish-killing oil spills.

And in perhaps the most heated exchange, one of the Ecuadorans suing Chevron pressed Watson to accept responsibility for oil-field contamination in her country.

I have come to say that Chevron needs to put on its pants and act like men and own up to the damage you have caused,” said Luz Trinidad Andrea Cusangua, speaking in Spanish with a translator at her side.

Chevron considers the Ecuadoran lawsuit a shakedown and has filed a racketeering case against the lawyers pursuing it. Facing Cusangua across the crowded room, Watson said the attorneys had misled her.

I understand you’ve been lead to believe by plaintiffs’ lawyers and others that Chevron is responsible,” he said, with his own translator repeating his comments. “What’s been made clear by the mountain of evidence we’ve produced over the last several years is that Chevron is not responsible.

Chevron shareholder meetings, sometimes held in San Ramon and sometimes in Houston, have for years attracted critics. Wednesday’s meeting brought an estimated 150 protesters to the company’s gate, while some of their colleagues who own shares in Chevron ventured inside to address the meeting. Security was tight both inside and outside the conference room, with investors passing through several checkpoints to enter.

Watson’s predecessor, David O’Reilly, sometimes turned combative during the annual meetings, especially when pressed on Ecuador. In contrast, Watson, who took Chevron’s helm in 2009, favors a more soft-spoken approach. On Wednesday, he frequently told critics that he agreed with them — to a point.

Despite the difference in style, Watson is no less adamant than O’Reilly about defending the company’s policies and operations. He expressed regret for the Nigeria explosion, for example, but told shareholders that the blast had not damaged the environment. He denied that Chevron suffered frequent spills in Angola.

He also said the company took responsibility for an oil spill off the Brazilian coast in November. But he defended Chevron’s handling of the incident, which has triggered fines and a criminal investigation in Brazil.

We feel very good about our initial response to that,” he said. “We acted in textbook fashion to stop the spill in four days.

A representative of Brazil’s United Federation of Oil Workers – a union that is trying to have Chevron barred from working in Brazil as a result of the spill — was denied entry to the shareholders meeting Wednesday. Watson said the representative, João Antonio de Moraes, lacked proper documentation to enter.

While many speakers at the meeting addressed Chevron’s operations in other countries, some focused on domestic issues, particularly fracking.

The practice, properly known as hydraulic fracturing, has led to a boom in natural gas production within the United States but also has prompted fears that it could contaminate water supplies. A shareholder proposal, voted on Wednesday, would have required Chevron management to report on the financial risks posed by proposed fracking regulations and moratoria in some communities.

But Watson argued that environmental concerns about fracturing can be addressed, a point he repeated after the meeting, in a brief conference with reporters.

It’s a once-in-a-generation benefit for the country, and we should take advantage of that, with the proper precautions,” he said.

About 73 percent of Chevron shareholders voting Wednesday rejected the fracturing proposal, according to the company’s preliminary count. Shareholders also rejected proposals to place on Chevron’s board an independent director with environmental expertise and split the jobs of board chairman and CEO.

miércoles, 30 de mayo de 2012

World's smallest artificial heart saves a baby

25 May, 2012, 14:04

An Italian heart surgeon holds a tiny titanium pump, the world's smallest artificial heart, which was implanted in a baby, at the Bambino Gesu' Hospital in Rome May 24, 2012 (Reuters / Alessandro Bianchi)
The smallest artificial heart in the world, weighing only 11 grams, was enough to save life of an infant boy suffering a deadly disease. Italian doctors who completed the surgery say it kept the baby alive till a donor was found.

This is the first time that such a small heart has been implanted to human. The boy suffered from dilated myocardiopathy, a disease which eventually would atrophy the heart muscle and stop its ability to pump blood. 

The operation was carried out at the end of March, but only now, when doctors may say with confidence that it was a success, was it made public. 

The baby, whose identity has not been disclosed, was able to survive for 13 days with the artificial heart before receiving an actual heart transplant

"At present, at more than one month from the surgery, the infant is in good health," surgeon Antonio Amodeo from Rome's Bambino Gesu hospital said. 

Italian heart surgeon Antonio Amodeo holds a tiny titanium pump at the Bambino Gesu' Hospital in Rome May 24, 2012 (Reuters / Alessandro Bianchi)
The little patient has been fighting for his life since the first month. Before the implant, the child had a mechanical pump and was suffering from an infection around the device. 

"From a surgical point of view, this was not really difficult. The only difficulty that we met is that the child was operated on several times before," Amodeo said. 

Doctors said the device, invented by American Doctor Robert Jarvik, had been previously tested only on animals.

The hospital needed special permission from Jarvik and the Italian health ministry before conducting the surgery.

"Every day, every hour, for more than one year he was with us. So when we had a problem we couldn't do anything more than our best," he said.

Doctors are convinced that the success of the operation could lead to the artificial heart becoming a permanent transplant option in the future. 

This is a milestone because it can be possible now to have permanent implantable devices," Amodeo said.

Ha sido desarrollado el primer "Circuito Integrado Químico"

martes, 29 de mayo de 2012 

Figure: The chemical chip can control the delivery of the neurotransmitter acetylcholine. This enables chemical control of muscles, which are activated when they come into contact with acetylcholine. 
Klas Tybrandt, estudiante de doctorado en Electrónica Orgánica en la Universidad de Linköping, (LiU) Suecia, ha desarrollado un circuito integrado a partir de productos químicos. Los resultados han sido publicados en la prestigiosa revista Nature Communications.

El grupo de investigación de Electrónica Orgánica en la Universidad de Linköping previamente había desarrollado transistores de iones para el transporte de los iones positivos y negativos, así como biomoléculas. Tybrandt ha logrado combinar ambos tipos de transistores en circuitos complementarios, de una manera similar a los tradicionales basados en silicio de la electrónica.

Una ventaja de los circuitos químicos es que el portador de carga consta de sustancias químicas con diversas funciones. Esto significa que ahora tenemos nuevas oportunidades para controlar y regular las rutas de señal de las células en el cuerpo humano.

Fig. 1. Arquitectura del IBJT. (A) La estructura del dispositivo principal de un BM, incluyendo una capa de membrana neutra intermedia. En tensión de polarización inversa y hacia adelante, los iones móviles se extraen de o se acumulan dentro de la capa intermedia, respectivamente. Esto da lugar a la rectificación de corriente iónica. (B) El IBJT polarizado de acuerdo con la configuración de emisor común. PEDOT: PSS electrodos con electrolitos acuosos generan las corrientes iónicas dentro del dispositivo. Emisor y el colector (selector de cationes, L x W ¼ 1,5 × 0,2 mm) se unen con la base (selectora de aniones) la definiendo la unión. (C) sección transversal vertical a lo largo de la configuración de emisor-colector (no a escala). El emisor y el colector (~ 250 nm de espesor PSS) se modelan en la parte superior de un substrato de PET. Un gel de PEG reticulado (referido como la unión) se emplea en la separación de capa aislante de espesor 10 micras SU-8. La base (~ 20 m de espesor) está en contacto con el gel y está cubierta por una capa de sello PDMS. IC es el flujo de cationes (MTH) desde el emisor al colector mientras IB, en estado estacionario, se compone principalmente de aniones (A-) migrando desde la base al emisor. (D) de arriba hacia abajo de la IBJT. Emisor y el colector se horizontalmente separados por 100 µm y la base cubre el área de unión total. (E) El símbolo del circuito propuesto para el PNP-IBJT

"Podemos, por ejemplo, envíar señales a las sinapsis del músculo, donde el sistema de señalización no pueden trabajar por alguna razón. Sabemos que nuestros chips obran con sustancias comunes de señalización, por ejemplo, la acetilcolina", dice Magnus Berggren, profesor de la electrónica orgánica y el líder del grupo de investigación.

The IBJT as an addressable delivery point for modulation of neuronal cell signaling. (A) Schematic illustration of the IBJT in a circuitry.  SH-SY5Y cells were cultured on  top of the collector electrode and ACh was  placed on  the emitter electrode. When switching on the device, ACh migrates through the E-C circuit and is released to the cells. 
El desarrollo de los transistores de iones, que pueden controlar y transportar iones y biomoléculas con carga, se inició hace tres años por Tybrandt y Berggren, respectivamente, un estudiante de doctorado y profesor en la electrónica orgánica en el Departamento de Ciencia y Tecnología en la Universidad de Linköping. Los transistores fueron utilizados por los investigadores del Instituto Karolinska de controlar la entrega de acetilcolina, la sustancia de señalización de las células individuales. Los resultados fueron publicados en la conocida revista interdisciplinaria PNAS.

Conjuntamente con Robert Forchheimer, profesor de codificación de información en LiU, Tybrandt ha dado el siguiente paso mediante el desarrollo de chips químicos que contienen también las puertas lógicas, tales como compuertas NAND que permiten la construcción de todas las funciones lógicas.

Su gran éxito se crea la base para una tecnología de circuitos completamente nuevos basados en iones y moléculas en lugar de electrones y huecos.

Información bibliográfica completa
Nature Communications: 10.1038/NCOMMS1869
Logic gates based on ion transistors
Klas Tybrandt 1, Robert Forchheimer 2 and Magnus Berggren 1*
1 Linköping University, Department of Science and Technology, Organic Electronics, SE-601 74 Norrköping, Sweden.
2 Linköping University, Department of Electrical Engineering, Division of Information Coding, SE- 581 83 Linköping, Sweden.


Afirman minera Barrick Gold causaría daños irreparables en la Republica Dominicana

El río rojo. En un preocupante espectáculo se convirtió el río Medellín. El Espectador
ORIGINAL: Sin Ataduras

El Río Maimón Rojo de la contaminación (Cotui – Piedra Blanca)
A) Algunos datos sobre la Barrick para los lectores
  1. a) Ejecutivos de la Barrick en la RD
    1. Gregory C. Wilkins, Presidente y Director Ejecutivo.
    2. Peter J. Kinver, Director Operativo.
    3. Faby Manzano, Corporate Social Responsibility Manager. fmanzano@barrick.com.
  2. b) Dirección de la Barrick en Canada
    1. Barrick Gold Corporation
    2. 161 Street , Suite 3700
    3. Brookfield Place, TD Canada Trust Tower
    4. Toronto, Ontario, Canada
    5. Telephone: 1-416-861-9911
    6. E-mail: Vincent Borg, Executive Director, vborg@barrick.com.
  3. c) Reservas de la Barrick en Pueblo Viejo, Cotuí
    1. Oro: 22, 000,000 onzas
    2. Cobre: 424, 000,000 libras (6% de las reservas de cobre de toda la compañía)
    3. Plata: 117, 000,000 onzas (10% de las reservas de plata de toda la compañía)
    4. Zinc: 2, 600,000 libras
  4. d) Producción de oro en la República Dominicana (RD)
    Oro: 1, 000,000 onzas (producción anual) (70% más de lo que producía la Rosario Dominicana)
B) Parte económica en la venta de oro por la Barrick
  1. a) Venta bruta total en 22 años de explotación:
    (22, 000,000 Oz de oro)(US$1120.00/Oz) = US$2.464 E10, o sea, US$24, 640, 000,000.00
  2. b) Costo total en 22 años de explotación:
    (22, 000,000 Oz de oro)(US$275.00) = US$6.05 E 09, o sea, US$6,050, 000,000.00
  3. c) Ganancia de la Barrick en la RD:
    US$24,640 millones – US$6,050 millones = US$18,590 millones en 22 años.
C.1) Reparto de beneficios entres la Barrick y la RD con los US$300 millones de inversión original.
  • US$18,590 millones – US$300 millones de inversión = US$18,290millones.
  • US$3,500 millones para la RD, 19.13%.
  • US$14,790 millones para la Barrick, 80.87%.
  • US$18,290 millones en total, 100%.
C.2) Reparto de beneficios entres la Barrick y la RD con los *US$3,000 millones de inversión falseada.
  • US$18,590 millones – *US$3,000 millones de inversión = US$15,590 millones.
  • US$3,500 millones para la RD, el 22.45%.
  • US$12,090 millones para la Barrick, el 77.55%.
  • US$15,590 millones en total, 100%.
  • *US$3,000 millones sacados por la Barrick como supuesta inversión. Dicha inversión inicial era de US$300 millones. Ahora la Barrick dice que son US$3,000 millones.
¡Vaya, la compañía, por arte de magia, le agregó otro cero! Pero así son las cosas del país hasta que los 9.5 millones de habitantes decidan lo contrario.

Nota. Esta distribución de beneficios del oro no cubre la venta del cobre, la plata y el zinc.
Una pregunta, ¿Vale la pena contaminar, casi eternamente, todas las aguas de un país de 9.5 millones de habitantes por solamente US$3,500 millones en 22 años?
D) NO a la instalación de la Barrick Gold ni ninguna otra compañía
Los daños ecológicos que la Barrick causará a la República Domininicana (RD) difícilmente puedan ser reparados.

Mientras esta situación se da, muchas personas, algunas de ellas con buenas intenciones, se dedican a pedir la REVISIÓN o la modificación del contrato en vez de pedir la NO INSTALACIÓN de dicha compañía o cualquier otra en el país.

Tampoco el Estado dominicano, en caso de que tuviera la tecnología, debería explotar la mina de oro de Cotuí.

Ese oro, muy difícil de extraer, debería quedarse en el subsuelo de la región.

¿Y qué dejó al país la Placer Dome cuando formó la Rosario Dominicana para explotar la mina de oro de los cianuros?

Solamente le dejó al país: contaminación, desolación, enfermedades, muertes y desempleo de toda la región.

Lo único que puede salvar al país, de 48,000 km2, de la contaminación extrema futura es la NO instalación de la Barrick y cualquier otra compañía en la República Dominicana.

Esos metales, incluyendo el oro, deben quedarse ahí de por vida. Nada puede compensar la contaminación de las aguas y los terrenos afectados. Y esas regiones de Cibao Oriental, y probablemente el país, serán contaminados y afectados por cientos y probablemente miles de años.

¡Miren que se lo digo hoy (03/28/10)!
Cuando los dominicanos dejemos instalar la Barrick en el país, este marcará el preámbulo de la contaminación futura y extremada del país de solamente 48,000 km2.

Y este será el comienzo de un triste final de que las pocas aguas que hoy abastecen el país estarán todas contaminadas.

Es increíble como la Barrick dice tantas mentiras para engañar al pueblo dominicano. No se le puede creer nada y no se sabe a ciencia cierta qué pasa con esa compañía en la RD.

¡Y miren, otra vez repito, que se lo digo hoy (03/28/10)!
Todas las aguas del país serán contaminadas. No solamente las aguas del Cibao Oriental serán contaminadas.

Todos los dominicanos seremos víctimas de la contaminación. Sin importar el status social: pobres, intermedios y ricos.

Y mientras, los extranjeros que hoy hacen daños al país se irán de la República Dominicana, con sus fardos llenos de oro, a vivir a otros países.

La única salida que la Barrick Gold le deja a los 9.5 millones de habitantes es luchar por sobrevivir o dejar el país. ¿Pero cuántos dominicanos podrán dejar el país?

Los 9.5 millones de habitantes tendrán una lucha a muerte contra la Barrick. Será una lucha en que los 9.5 millones de habitantes lucharán por sus vidas.

Pero por otro lado, el dejar la Barrick nuestro país implica que otros intereses como los que dicha compañía tiene en Chile, la Argentina, Guatemala, El Salvador, etc., verán la vulnerabilidad dicha compañía (la Barrick) al irse de la República Dominicana (RD) totalmente derrotada por los 9.5 millones de habitantes.

La soberbia de la Barrick es enorme. Y contra esa soberbia tienen que luchar los 9.5 millones de habitantes si quieren sobrevivir.

Esta situación hará que la Barrick gastará lo que sea para comprarse a todo aquel que no tenga conciencia de que también él/ella será víctima de la delicada situación que se avecina en la República Dominicana.

Por otro lado, recuerden el dicho que dice: “dime con quién andas y te diré quién eres”. Y esta situación se ajusta a ciertos lobos vestidos de ovejas que pretenden abanderarse de los salvadores de los 9.5 millones de habitantes del país.

Claro, en estos momentos de desesperación que vive el pueblo dominicano hay que mezclar a mansos y a cimarrones. Pero nunca darle el liderazgo a los cimarrones.

También por otro lado, la lucha intestina que hoy tienen la mayoría de los candidatos dominicanos, que dicho sea de paso casi ningunos sirven, no es nada en comparación con la lucha futura que efectuarán los 9.5 millones de habitantes de la República Dominicana por la sobrevivencia.

Y que ellos mismos (los candidatos dominicanos), como parte de los 9.5 millones de habitantes, tendrán que ser parte de esa lucha como una forma de ellos mismos sobrevivir juntos a sus familiares.

Y no importa el dinero que algunos fariseos reciban de la Barrick. Cuando no haya agua para el consumo de los seres vivientes del país, de nada vale el dinero que se le coja a la Barrick. Y no importará la cantidad.

Las protestas contra la Barrick estarán al doblar de la esquina. Y dichas protestas no habrá que verla como reclamos económicos.

Serán protestas de la población dominicana por el derecho a la vida. O sea, por el derecho a existir.

¿Cómo pueden el Estado dominicano y la población darse cuenta de las contaminaciones de las aguas a nivel nacional?

¡Muy simple…, veamos…!:
  1. El país tienes cerca de 41 universidades, 32 provincias y varias instituciones estatales que pueden adquirir analizadores digitales de aguas en todo el territorio nacional.
  2. Estos analizadores de agua y energía pueden analizar más de 250 elementos y compuestos. Dependiendo de su precio, su valor promedio es de unos US$5,500.00/aparatos.
  3. Si el país comprara unos 200 de estos aparatos para distribuirlos de a dos en cada provincia, las universidades y las instituciones estatales se gastaría unos: 200 * 5,500 = US$1, 100,000.00 en total. Esta cantidad es totalmente irrisoria en comparación con los servicios importantísimos que van a dar al país.
  4. Su uso es digital y una vez bien calibrados los200 aparatos deben de dar, más o menos, el mismo resultado.
  5. No se trata de espectrómetros de masas ni nada complicado por el estilo. El manejo de estos aparatos es totalmente digital y simple.
  6. Creo que la delicada situación nacional demanda que se compren urgentemente estos aparatos. No quiero involucrarme en esta compra-venta porque quiero, hasta la muerte, estar totalmente limpio de la corrupción que abarca todo el país.
  7. La belleza de estos aparatos, es que el Estado dominicano no necesita que la Barrick o cualquiera otra institución o compañía les den la composición de la mena que contiene la mina de oro y otros metales. Tampoco el Estado dominicano necesitará recibir del laboratorio de la Barrick o cualquier otra compañía los análisis de las contaminaciones de todas las aguas del país. 
  8. He usado estos aparatos que disponen de un programa de computadora para cada elemento o compuesto. Claro, todo depende del precio.
Indudablemente que para los metales raros como molibdeno, tungsteno, wolframio, etc., estos aparatos son más caros. Pero este no es el caso de la República Dominicana.

Los análisis que actualmente requiere el país son, entres muy pocos: silicio y sus compuestos, mercurio y sus compuestos, azufre y sus compuestos, cobre, plata, zinc, etc.

D) Entrevista con el director ejecutivo de la Barrick Gold
Estuve viendo la entrevista con el Lic. Fernando Sánchez, director ejecutivo de la Barrick Gold y ex-ministro de Mina del Perú.

La entrevista fue totalmente pobre. Probablemente la Barrick mandó a su relacionador público número uno a dicha entrevista. El señor Sánchez inundó de mentiras a los oyentes sin lograr convencer a nadie.

Yo, particularmente, invito a la población dominicana a no creer nada de lo que la Barrick publique en internet o cualquier persona en particular. Muchos de los datos de la Barrick son falsos.

Actualmente solamente publican los que dicha compañía quiere que la comunidad dominicana sepa.
Algunos pormenores que contestó Fernando Sánchez en la entrevista:
  1. La contaminación de Cotuí fue producto de pollos y hamburguesas contaminadas con bacterias”. Comentarios. La Universidad Autónoma de Santo Domingo (UASD), la Academia de Ciencias y la lógica han demostrado las mentiras del señor Sánchez.
  2. Que se va quedar el oro enterrado para toda la vida de no explotarlo la Barrick”. Comentarios. Yo propongo que el oro se quede enterrado de por vida.
  3. El plan del Estado todavía no es conocido por la Barrick”. Comentarios. ¡Vaya…, que representantes del Estado tenemos los dominicanos!
  4. La Barrick está limpiando la contaminación dejada por la Rosario Dominicana”. Pregunta, ¿Y a dónde se está llevando la Barrick la contaminación dejada por la Rosario Dominicana? ¿A la presa de Hatillo, al rio Yuna y a sus afluentes?
  5. Regalía e impuesto sobre la renta. El señor Sánchez hizo algunos comentarios. 
  6. El Estado dominicano una vez que la empresa haya recuperado toda su inversión de US$3,000 millones, va a recibir un total de US$ 3,500 millones en los veinte y dos años de explotación”. Pregunta, ¿Valen todos los terrenos del Cibao Oriental o del país, con extremadas contaminaciones futuras de todas sus aguas, los US$ 3,500 millones que el Estado va a recibir en los 22 años? Comentarios. Debemos recordar que la Barrick va a producir 22,000,000 de onzas de oro en veinte y dos años.
  7. Algunos sectores con intereses particulares se están oponiendo a la Barrick. Y a esta compañía les están haciendo muchos daños”. Comentarios. Poniéndome yo como uno de esos sectores, me opongo a la INSTALACIÓN de la Barrick o cualquier otra compañía en la República Dominicana (RD) porque hay grandes riesgos de que gran parte de los 48,000 km2 o todo el territorio nacional sea contaminado. Y yo no tengo ningún interés particular en mi posición de la NO INSTALACION de la Barrick en la RD.
  8. La REVISIÓN (no de la NO INSTALACIÓN como muchos dominicanos proponen) del contrato depende del poder ejecutivo. No de los Congresistas”. Comentarios. Creo que la no instalación de la Barrick en el país solamente dependerá de los 9.5 millones de habitantes de la media isla que lucharán por sus vidas. No del Poder Ejecutivo ni de los Congresistas.
  9. Nadie puede ir a su casa a tomarse un café sin previo aviso”. Comentarios. El Sr. Sánchez hizo referencia a la Universidad Autónoma de Santo Domingo (UASD), la Academia de Ciencias y Salud Pública, a las cuales no se les permitió el acceso de dichas entidades a los terrenos contaminados de la Barrick. ¿Pero qué oculta la Barrick con esta prohibición? ¿Y no son estas instituciones parte del Estado dominicano? ¿Y no es el Estado dominicano codueño de la mina?
  10. Se han pagado a todo los dominicanos por la ocupación de los terrenos”. Comentarios. Yo personalmente pude palpar, en la trayectoria de Maimón a Cotuí, y que viajaba en una güagüita, que solamente se les ha dado, a los campesinos que han vivido por generaciones y generaciones en esos predios, RD$50,000.00. Comentarios. La Barrick, como una forma de intimidación, acaba de romperle los cristales al vehículo del fiscal de Cotuí que dictó sentencia en contra de ella y a favor de los campesinos a lo cual la referida compañía les quitó compulsivamente sus terrenos.
  11. Que Dios salve a la República Dominicana ya que este, y los demás problemas, se lo estamos dejando a la carencia y los altos precios del petróleo.
Finalmente, el slogan que los 9.5 millones de habitante tenemos que tener es: NO INSTALACIÓN DE LA BARRICK Y QUALQUIER OTRA COMPAÑIA EN LA REPÚBLICA DOMINICANA PARA EXPLOTAR EL ORO DE COTUÍ.

Para información de los lectores:
Precio de cierre del oro (03/26/10, 5:30 p.m.): US$ 1,104.30/onza.
Precio de cierre del petróleo (03/26/10, 5:30 p.m.): US$ 80.00/barril.
NYC 03/28/10 www.wjerez.blogspot.com
Por William Jerez

Escrito por: EMILIO ORTIZ (economía@elnacional.com.do)
17 Noviembre 2011

El presidente de Barrick Pueblo Viejo dijo que con recursos que obtendrá, el Estado podrá financiar cualquier proyecto

Ejecutivos de Barrick Pueblo Viejo y del Grupo Corripio en el almuerzo semanal.
El presidente de la empresa Barrick Pueblo Viejo hizo un llamado a la sociedad dominicana para que vigile lo que harán los gobiernos que manejen el Estado en los próximos 25 años con los recursos multimillonarios que obtendrá con los beneficios de la explotación de las reservas mineras de Pueblo Viejo, que afirmó serán suficientes para financiar cualquier plan de desarrollo.

El ingeniero Manuel Bonilla dijo que el alza de los precios internacionales del oro, que estima seguirán incrementándose en los años por venir, permitirán que los ingresos por concepto de explotación minera sean la principal fuente de recursos del Estado dominicano.

Opinó que se trata de recursos que pueden convertirse en el eje del desarrollo nacional, por lo que hay que vigilar que no sean usados simplemente para gastarse, sino para inversiones que modifiquen en forma positiva el nivel de vida de los dominicanos.

El presidente de la empresa dijo que en su condición de dominicano, sería el primero en advertir que los ingresos provenientes de la explotación de las reservas de Pueblo Viejo sirvan básicamente para el financiamiento de proyectos dirigidos a beneficiar a todos los dominicanos.

Bonilla adelantó que el inicio de la producción de la empresa Barrick Pueblo Viejo, prevista para mediados del año próximo, será impactado en forma positiva por la duplicación de los precios del oro, ya que al momento de la firma del contrato con el Estado, promediaba los 650 dólares la onza y hoy día superan los mil 700 dólares en los mercados internacionales.

Eso permitirá que la recuperación de la inversión realizada por la multinacional para la extracción de oro, plata, cobre y zinc de las reservas de Pueblo Viejo, en la provincia Sánchez Ramírez, se reduzca en forma considerable y como consecuencia de ello la empresa comience a obtener beneficios que por mandato contractual deberá compartir con el Estado dominicano, indicó el ejecutivo.

Bonilla participó como invitado al almuerzo semanal de los medios de comunicación del Grupo Corripio, acompañado de la doctora Juana Barceló, directora de Asuntos Legales; Jorge Esteva, gerente de comunicaciones; Sergio Roiberg, presidente de la agencia de publicidad Newlink International; José Calzada, gerente en el país de la publicitaria y Fernando Martínez, gerente de cuentas.

En su intervención, el presidente de Barrick Pueblo Viejo dijo que el proyecto Pueblo Viejo será, al momento de iniciar su operación, el buque insignia de esa multinacional, debido al volumen de la inversión, la cantidad de minerales involucrada, la tecnología de punta aplicada y la remediación ambiental.

Sobre este último punto, el ingeniero Bonilla dijo que la inversión que realiza la empresa para la remediación ambiental de la zona no tiene precedentes en el mundo de la minería.

Precisó que el daño realizado al medio ambiente con la explotación de los minerales de la reserva por parte de la Rosario Dominicana, tardará años en ser superado y requerirá una inversión cercana a los 450 millones de dólares.

De igual modo, dijo que el contrato firmado con el Estado dominicano es el más beneficioso que minera alguna haya firmado.

Adelantó que cuando la mina esté en toda su capacidad de producción, los ingresos del Estado y de la empresa serán casi iguales, a lo cual contribuirá además el alza del precio del oro en los mercados internacionales.

Dijo que en la construcción de las obras civiles necesarias para el inicio de la explotación de la reserva minera, participan unos nueve mil 200 trabajadores.

Un apunte

Para la remediación ambiental en la zona donde se encuentra la reserva minera de Pueblo Viejo, debido a la crisis ambiental creada por la explotación irracional por parte de la Rosario Dominicana, será necesaria una inversión de más de 450 millones de dólares.

Geometry Of The Big Bang

ORIGINAL: Science20
May 28th 2012

The deeper we look into the universe, the deeper we look back in time. When in the night sky you see planets like Jupiter and Saturn, you look about an hour back in time. Look at the stars, and you are looking back in time anywhere from years to several centuries. Bring a binocular to a dark site and you will be able to see galaxies millions of years back in time. Get a decent telescope to the same site and you look even further back. 

However, there is a limit to how deep you can peek. No matter what equipment you bring, and no matter what part of the electromagnetic spectrum you observe, you can't look back more than 13.7 billion years. What do we see when looking at these times long past? A glow. A nearly uniform microwave glow across the full sky. The cooled-down remnant of the fierce flash of light emitted at the dawn of time.

Visualizing The Big Bang
If you accept these words about the big bang radiation at face value, you are probably not giving them enough thought. Just think for a moment about this radiation surrounding us. Does that make sense? How can we be surrounded by radiation from the big bang 13.7 billion years after the fact? Ignite a bomb, or do whatever you need to do to cause a fireball that emits light and matter. No matter how big a fireball you create, the light will fly out faster than the matter. As a result, observers who are part of the explosion and fly out with the ejected matter, will not keep up with the light and soon not see any of it. So how on earth can we be swimming in the light from the explosion that we ourselves are part of?

Ok, you probably know the reply to this objection: the big bang was not an explosion that happened somewhere. It was an explosion that happened everywhere. Knowing this answer, how do you visualize the big bang? As some giant carpet bombing?

Such visualizations don't make much sense. Any carpet bombing analogy leads to an avalanche of more problematic questions. Who or what orchestrated all these bombs and made them ignite at the same time? And how can it be that the radiation from the big bang is uniform across the sky? Uniformity means each individual bomb in this carpet bombing not only ignited simultaneously, but also each bomb must have been an accurate copy of all the others. Who ordered these zillions of copies of the same bomb, and made them ignite at the same time?

Most pop science books when reaching this point will make some remarks about bombs explodingin space while the big bang creates space. This is the moment in the discussion where galaxies get depicted as raisins in expanding bread dough. Yet, such considerations and analogies do not make the uniformity riddle, referred to by cosmologists as the "horizon problem", go away.

At this point your favorite pop science books will probably introduce the concept of cosmic inflation. As this follows the picturing of our universe as rising bread dough, this leaving the reader with a vague notion of a magical multiplication of dough preceding the baking of the cosmic raisin bread.

If all of this is a reliable description of the big bang theory of cosmology, you should not believe a word of this theory. But of course it isn't. Cosmologists don't need any magical bread multiplication. Forget loafs of bread, forget exploding bombs, forget rubber sheets or whatever you were made to believe represents the big bang. Today, I will present you with a much more satisfying visualization. A visualization that captures the main features of the early universe and that also depicts quite accurately the late stage of evolution the universe has entered. This visualization is relativistically correct, it features an accelerating expansion, and it depicts what is without any doubt the most elegant and most beautiful big-bang model ever constructed.

The visualization will shed new light on the horizon problem, and also suggests an answer to the question "what came before the big bang?". An answer that might surprise you and that at the same time might eliminate any aversion to the big bang cosmology that you might carry with you. And best of all: this relativistic visualization does not require any heavy math. All that is needed is some simple geometrical concepts. The secret to enable this feat is to sacrifice two of the spatial dimensions. This gives us a universe with one time and one spatial dimension that can be visualized as a curled up surface in a 3D space-time.

One last word and a bit of a disclaimer before we start. Is the visualization I will present here the true and unique model of our expanding universe? No it isn't. Firstly, it is an idealized model, and secondly when it comes down to the very early stages of the universe we enter terra incognita. The picture I will present lead us right through the moment of the big bang. Yet, what actually happened at the very moment of the big bang no one can tell for sure. Astronomers can look back down to 380,000 years after the big bang. At the LHC we can recreate the conditions of the universe down to much earlier times of about 0.00000000001 seconds after the big bang. Still earlier times are not experimentally accessible to us, as we lack particle accelerators powerful enough to recreate the energies required. Nobody can claim to know what happened at times and energies not accessible to us. However,we do have theories that go down to much earlier times. All these theories are speculative in nature, and that includes the theory on which below visualization is based.

I should stress here that regardless of these disclaimers, below visualization honors Einstein's well-tested general theory of relativity, and at the same time it avoids any singularities that would make the math blow up. As such it provides us with an excellent tool to sharpen our intuition when it comes to issues like the horizon problem.The whole point here is: learn from this visualization and use it to sharpen your thinking about issues surrounding big bang theories, but don't get carried away into thinking that this is the last and final word on what happened at time zero.

Having said this, despite the physics at time zero being unknown to us, the big bang phenomenon in itself is not in any way speculative. The fact that our universe is expanding is as certain as the fact that earth's surface is curved. The picture that will be presented below gives a description of the universe akin to the spherical earth description. It provides us with the most symmetric description of our universe: a 'spherical space-time' model. As space-time distances don't behave like spatial distances, a 'space-time sphere' takes the shape of a hyperbolic geometry that enforces a description of an accelerating"open universe". Sounds enigmatic? Read on and all will be clear in a few minutes.

Beauty Bouncing Back
In 1917, just two years after Einstein published his general relativity theory, the Dutch mathematician and astronomer Willem de Sitter came up with a four-dimensional space-time that fitted Einstein's equations. The way he obtained his solution was remarkable: De Sitter had started from a five-dimensional hyper-space-time in which he 'carved out' a four-dimensional hyper-surface at constant distance from a given point.The resulting hyper-space-time sphere, he discovered, satisfied Einsteins equations of general relativity. Amazingly, this solution was obtained in the absence of matter. The space-time that De Sitter had created was purely driven by vacuum energy. Upon hearing of the De Sitter solution, Einstein was convinced this solution could not correspond to any physical reality, and he frantically started looking for errors in De Sitter's calculations. He soon gave up his attempts. De Sitter's math was flawless.

Einstein and De Sitter arguing empty universes
Einstein was shocked by De Sitter's results, as he was convinced that his theory of general relativity embodied Mach's principle. Loosely speaking, this principle states that dynamics and inertia only exists in relationship to distant stars and all other matter composing the universe. His theory of general relativity stated how matter curved space-time, and how space-time curvature in turn made the same matter move. From a Machian point of view, a most satisfying self-consistent construction. A construction now thorn apart by a solution that contained no masses at all. Einstein was forced to conclude that no matter how valid his gravitational field equations, they allowed for massless solutions and therefore did not embody Mach's principle.

Five years later, in 1923, British astronomer Arthur Eddington and German mathematical physicist Hermann Weyl discovered that the universe described by De Sitter's space-time hypersphere isnot static. Rather, De Sitter's equations describe an expanding universe. Einstein, and many others who were convinced they lived in a stable and static universe, immediately brushed De Sitter's model aside as a mathematical artifact. An artifact that unfortunately was contained in the equations for general relativity. Six years later, in 1929, Edwin Hubble published hard evidence that our universe is expanding. By that time De Sitter's work had fallen in disgrace and other cosmological models were available based on Friedmann's and Lemaitre's work that, although less elegant, had the distinct advantage of allowing the effects of mass to enter the model.

De Sitter's model lay dormant for more than half a century. However, as is often the case with beautiful math, it has the tendency to pop-up again and to re-enter physics. Indeed, in the 1980's De Sitter's model bounced back into mainstream physics and cosmology. This time as the key model to describe the very early universe and as a solution to the horizon problem. Finally, the place of De Sitter's model in cosmology got permanently secured when at the very end of the twentieth century it was discovered that the expansion of the universe is accelerating, and that our own universe is inevitably heading for an evolution described by De Sitter's model.

From Minkowski To De Sitter Universes
As mentioned above, we will be constructing a two-dimensional space-time that describes a universe with one spatial and one temporal dimension.How does it feel to live in such a linear universe? Imagine an astronomer living in this narrow linear world. Where we have at our disposal two hemispheres of sky, the full sky available to our linear astronomer consists of no more than two antipodal points. That's all.Two points of light at the opposite ends of a long tunnel of vanishing width. Imagine this astronomer to look deep into both ends of the tunnel. The latest technology available allows the astronomer to observe the deepest light emerging from these two points. The light emitted at the dawn of time. Amazingly, both lights appear to shine with exactly the same intensity and the same color. How can this be? These far-away starting points of the universe can not have been in prior communication with each other, so how can they shine as two copies of the same light?

Minkowski's flat spacetime
The astronomer knows relativity theory and is fully aware that in his narrow universe causations are observer-independent and absolute. In a space-time description the causations can be visualized as parallel straight lines. In the above plot these are shown in red (causations from left to right) and blue (causations from right to left) lines. The slope of the lines of causation represents the speed of causation, also referred to as the speed of light, again an observer-independent absolute quantity. Each point in this so-called Minkowski space-time is crossed by two causations, reflecting the fact that any event is the result of causations arriving from the left as well as from the right. One such pair of causations is highlighted with thick yellow and blue lines.

In this Minkowski picture it is quite enigmatic that the left-propagating and right-propagating light emitted at the dawn of time are observed to have the same color. The emission of both light signals at the dawn of time are two separate events the don't share any common cause (see below figure).

A Minkowski description leaves an observer located at the question mark puzzled how come the two opposing light rays reaching her from the distant past are strongly correlated

Could it be that the space-time our astronomer lives in is not Minkowskian but curved? Curved in such a way that both light rays reaching the astronomer originate from one and the same event? The answer is "yes", this is very well possible. One can build a curved space-time consisting of left- and right-oriented lines of causations that cross each other. What might surprise you is that this can be achieved without bending the straight paths of causation. There is one unique way to achieve this, and it requires us to go one dimension higher than the space-time we want to describe. The curved space-time thus created is again two-dimensional (one spatial and one temporal dimension) and takes the shape of a hyperboloid embedded in a three-dimensional (two spatial dimensions and one time dimension) space-time.

De Sitter universe with one spatial (circumferential) and one time (upward) dimension embedded in a 3D Minkowski space-time. This 3D background serves as an aid in visualizing the universe, and is not in any way part of the universe.

This is the De Sitter universe with 1+1 space-time dimensions. The lines of causation (red and blue lines) remain straight, and run without beginning or end. The universe thus created is past and future infinite, and the big bang is replaced by a compact phase: a 'big bottleneck' also referred to as a 'big bounce'. At this bottleneck the universe is hot and dense and opaque to any light. Away from the bottleneck, the universe expands both towards future infinity and towards past infinity.

This is an utterly simple universe model that at one fell swoop eliminates a multitude of issues surrounding big-bang cosmologies. Firstly, there is no singularity plaguing the model. At the 'big bottleneck' the universe attains a minimum size, but at no stage of evolution does the size of the universe drop to zero. Secondly, there is no issue of lines of causation terminating at a time zero. No fine-tuning nor any special boundary conditions are required at time zero. Thirdly, the universe is time-symmetric and therefore fully compatible with the known fundamental laws of physics that are strictly time symmetric. And finally, with this cosmological model the "dawn of time" has disappeared and with it has the horizon problem. More in particular, when tracing back the opposing red and blue light rays arriving at an event in the distant future (and event at a distance from the bottleneck much further away than the bottleneck diameter), one notices that both light rays, when continued through the bottleneck towards time "minus infinity", get arbitrarily close in terms of distances expressed in the local diameter of the universe (the local circumference of the hyperboloid).

Big Bounce, Big Symmetry, Big Speculations
I have argued before in favor of a 'big bounce'. The argument at that time was based on thermodynamic considerations and the need to eliminate the special character of the low-entropy starting point of the universe. Here, the big bounce follows from a search for the most symmetric solution to Einstein's equations. Other speculative approaches such as 'Loop Quantum Cosmology' also point towards big bounce scenarios. It is tempting to interpret these results as diverse hints all pointing towards our universe having bounced 13.7 billion years ago. Although merely a speculation, this is a very tempting speculation.

Some researchers go even further and contemplate whether the ultimate symmetry present in the De Sitter space-time is perhaps directing towards a kinematics more general than the relativistic kinematics derived by Einstein. If it is indeed the case that Einstein didn't go far enough, and modelling the full evolution of our universe requires a new kinematics that goes beyond special relativity, all of modern physics needs to be rebuild... Another subject to be added to the ever growing list of intriguing speculations to be discussed here.