Puzzling asymmetries

In a recently published paper, the LHCb Collaboration has reported on a possible deviation from the Standard Model. Theorists are now working to calculate precisely this effect and to evaluate the implications that such unexpected result could have on the established theory.

 

The Standard Model is able to predict the decay rates of particles with high precision. In most cases, experimentalists confirm the value predicted by theory and the figure is added to the official publications. However, this time, things seem to have taken a different route.

Studying data collected in 2011, the LHCb Collaboration found that in a specific decay – a B particle transforming into a K particle plus two charged muons (B -> Kμ-μ+) – the branching ratio of the neutral B in the corresponding decay (i.e. B0 -> K0μ-μ+) is different from that of the positively charged B (i.e. B+ -> K+μ-μ+). Such an “isospin asymmetry” between the decays of differently charged B particles was not expected, as theory predicts the corresponding value to be very close to zero.  “There had been hints of such an effect from previous experiments (CDF, Belle and BaBar), which agree with the new higher-precision result from LHCb,” explains Pierluigi Campana, LHCb Spokesperson. “This result has been made possible by the strong and continuous support from the LHC operations team for the LHCb physics program.” 

Theorists are now busy in calculating the exact figure that we should expect for this specific asymmetry. If theory confirms the deviation, this new experimental result could open the way to further investigations of possible new physics in B decays. 

Read more details on the LHCb website and the LHCb scientific paper.

Friday, May 25th, 2012, by CERN, Filed under: CERN,Ciencia,Cosmologia,Fisica,Fisica de alta energia,Fisica de Materiales,Fisica de particulas,LHC,Matematicas,Materia,Mecanica cuantica,Science,Sincrotrón | | | No Comments

La densidad de la ‘Posidonia’ del Mediterráneo podría disminuir un 90% a mediados de siglo

Un estudio realizado por investigadores del Consejo Superior de Investigaciones Científicas (CSIC) revela que la densidad de plantas de la especie marina Posidonia oceanica podría disminuir un 90% a mediados de este siglo debido al calentamiento del agua superficial del mar Mediterráneo. Los resultados, que aparecen publicados en el último número de la revista Nature Climate Change, apuntan a una “extinción funcional” de la especie con un escenario “moderadamente optimista” de emisión de gases de efecto invernadero.

El trabajo, elaborado en el marco de los proyectos españoles VANIMEDAT-2, MEDEICG, ESCENARIOS y el europeo SESAME, examina la evolución temporal de la temperatura superficial máxima esperada durante el siglo XXI en el Mediterráneo occidental. Para ello, los científicos han empleado proyecciones de diez modelos climáticos globales y dos modelos regionales.

Read more »» La densidad de la ‘Posidonia’ del Mediterráneo podría disminuir un 90% a mediados de siglo

Thursday, May 24th, 2012, by Manuel, Filed under: Biodiversidad,Biologia,Calentamiento Global,Cambio climatico,Ciencia,CSIC,Ecologia,España,Investigacion,Medio ambiente,Science | | , , , , , , , , | No Comments

Baterías de litio 10 veces mejores

Consiguen obtener baterías de litio con ánodo de silicio que aguantan más de 6000 ciclos de carga y tienen una capacidad 10 veces superior a las actuales.

¿Está ya hasta las narices de tener que recargar continuamente las baterías de su smarphone, de su portátil o de su cámara? Quizás las baterías con una capacidad 10 veces superior a las actuales estén a la vuelta de la esquina. Al menos, según un nuevo estudio de la Universidad de Stanford.

 

 

Double-walled Anode

The new double-walled silicon nanotube anode is made by a clever four-step process: Polymer nanofibers (green) are made, then heated (with, and then without, air) until they are reduced to carbon (black). Silicon (light blue) is coated over the outside of the carbon fibers.

Finally, heating in air drives off the carbon and creates the tube as well as the clamping oxide layer (red).

Image courtesy Hui Wu, Stanford, and Yi Cui

.

Las mejores baterías actuales se basan en el uso de iones de litio. Son ligeras y almacenan bastante energía, aunque no suficiente para los requerimientos que necesitamos para el presente y el futuro. Se basan en el flujo de estos iones a través de un electrolito que está entre un ánodo y un cátodo. El ánodo está hecho de carbono y la capacidad de la batería para almacenar carga depende de cuantos iones de litio pueden acomodarse en el ánodo. Cada 6 átomos de carbono (en forma de grafito) se puede acomodar un ión de litio. Desde hace un tiempo se viene intentando sustituir este tipo de ánodo por uno de silicio que es capaz de fijar cuatro iones de litio por cada átomo de silicio. Esto permitiría aumentar, y mucho, la capacidad de este tipo de baterías (unas 10 veces más capacidad que las actuales).

Lo malo es que cuando se ha intentado construir este tipo baterías (y se ha intentado durante más de una década) el número de ciclos de carga es muy bajo y la batería termina siendo inútil al poco tiempo. Esto se debe a que la estructura del silicio se resiente y termina degradándose. El ánodo absorbe tantos iones que se hincha hasta ocupar un volumen cuatro veces superior y el electrolito reacciona con el silicio recubriéndolo con un compuesto que inhibe futuras recargas. Cuando la batería se descarga el volumen del ánodo vuelve a disminuir creándose grietas en donde vuelve a atacar el electrolito. En unos pocos ciclos la batería es inservible.
Ahora Yi Cui y su equipo han conseguido una batería de este tipo que aguanta 6000 ciclos con una carga al final de ese periodo de un 85% la original, suficiente para ciertas aplicaciones. Un automóvil eléctrico podría funcionar durante casi 20 años con este tipo de batería para llevarnos al puesto de trabajo todos los días.
Este grupo de investigadores ha ido mejorando la duración de este tipo de ánodo haciendo que estuviera compuesto de nanohilos. En su último diseño han creado un ánodo compuesto de nanotubos de silicio de doble pared recubiertos con una pared de óxido de silicio.
Esperan simplificar el proceso de fabricación para que así el producto pueda llegar al mercado en algún momento. ¿Se imagina recargar su smarphone cada diez días en lugar de todas las noches?

Fuente  http://neofronteras.com/?p=3830

Fuentes y referencias:
Nota de prensa.
Artículo original.

Thursday, May 24th, 2012, by Manuel, Filed under: Ciencia,Fisica,Fisica de Materiales,Quimica,Science,Technology,Tecnologia | | , , , , , , , | No Comments

News from the Library: Looking for materials properties? Find the answer in CINDAS databases

Materials properties databases are a crucial source of information when doing research in Materials Science. The creation and regular updating of such databases requires identification and collection of relevant worldwide scientific and technical literature, followed by the compilation, critical evaluation, correlation and synthesis of both existing and new experimental data.

 

The Center for Information and Numerical Data Analysis and Synthesis (CINDAS) at Purdue University produces several databases on the properties and behaviour of materials. The databases include:

– ASMD (Aerospace Structural Metals Database) which gives access to approximately 80,000 data curves on over 220 alloys used in the aerospace and other industries

– the Microelectronics Packaging Materials Database (MPMD), providing data and information on the thermal, mechanical, electrical and physical properties of electronics packaging materials, and

– the Thermophysical Properties of Matter Database (TPMD), covering the properties of over 5,000 materials with approximately 50,000 data curves.

Trial access to these resources is available until 31 August 2012, so you are very welcome to try these databases and send us your feedback at library.desk@cern.ch.

Online access to the databases here.

Thursday, May 24th, 2012, by CERN, Filed under: CERN,Ciencia,Cosmologia,Fisica,Fisica de alta energia,Fisica de Materiales,Fisica de particulas,LHC,Matematicas,Materia,Mecanica cuantica,Science,Sincrotrón | | | No Comments

Ombuds’ Corner: Social exclusion

In this special video edition of the Ombuds' Corner, Vincent Vuillemin takes a look at a social exclusion at CERN. Please note that the characters and situations appearing in this work are fictitious, and any resemblance to real persons or events is purely coincidental.

 

Contact the Ombuds Early!

Thursday, May 24th, 2012, by CERN, Filed under: CERN,Ciencia,Cosmologia,Fisica,Fisica de alta energia,Fisica de Materiales,Fisica de particulas,LHC,Matematicas,Materia,Mecanica cuantica,Science,Sincrotrón | | | No Comments

Thinking machines, the creation of the computer

Episode of the television program History Channel "Modern marvels" in 1995. Traces the history of the computer from Charles Babbage’s Victorian counting machine to the desktop models of the 1990s.

Thursday, May 24th, 2012, by CERN, Filed under: CERN,Ciencia,Cosmologia,Fisica,Fisica de alta energia,Fisica de Materiales,Fisica de particulas,LHC,Matematicas,Materia,Mecanica cuantica,Science,Sincrotrón | | | No Comments

Academic Training Lecture Regular Programme: How Large-Scale Civil Engineering Projects Realise the Potential of a City

How Large-Scale Civil Engineering Projects Realise the Potential of a City (1/3), by Bill Hanway (Excecutive Director of Operations, AECOM Europe).

 

Wednesday, June 6, 2012 from 11:00 to 12:00 (Europe/Zurich)
at CERN ( 80-1-001 – Globe 1st Floor )

In this series of three special lectures, leading experts from AECOM would explore the impact of a trio of major projects on a single city.
In common with every metropolis, London has run-down districts and infrastructure in need of upgrading. The lectures propose to cover three of the biggest challenges: regenerating run-down areas; reducing congestion and transporting people more efficiently; and improving water and wastewater systems.
Each project contributes to a collective public aim – to realise the potential of a growing city, and ensure its healthy, sustainable and competitive future.

Lecture 1: Into the lecture series and The London 2012 Olympic Games
Most cities share a group of common complex challenges – growing populations, ageing infrastructure, and mitigating the effects of climate change. These require similar responses to find the most appropriate solutions to make sure that all urban dwellers can have the basics of food, warmth, clean water and shelter. In addition, they must have the ability to lead full and productive lives being able to travel around easily and effectively, that they have homes, jobs and places to enjoy their leisure time. To achieve all of this requires a holistic vision and collaborative approach involving all stakeholders from local, regional and national government and utility companies, to private business and local communities.

To provide an example of the holistic approach to reworking old cities, this series begins with a dynamic first-hand account from a key player in one of Europe’s largest regeneration projects. The Lower Lea Valley in East London was a rundown and melancholic place in 2000, but its radical transformation has created an exemplary setting for the 2012 Olympic Games. In the spirit of previous London developments based around green spaces, the parkland created for the Games (the setting for 35,000 homes) is designed to act as a catalyst for improvement The legacy masterplan is crucial for this and the speaker’s team has gone on to win the Olympic masterplan competition for Rio 2016.

Find details on the subsequent lectures here.

Thursday, May 24th, 2012, by CERN, Filed under: CERN,Ciencia,Cosmologia,Fisica,Fisica de alta energia,Fisica de Materiales,Fisica de particulas,LHC,Matematicas,Materia,Mecanica cuantica,Science,Sincrotrón | | | No Comments

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