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Benvenuti in queste pagine dedicate a scienza, storia ed arte. Amelia Carolina Sparavigna, Torino

Tuesday, February 14, 2012

Flying pyramids



Intrinsic Stability of a Body Hovering in an Oscillating Airflow

Bin Liu, Leif Ristroph, Annie Weathers, Stephen Childress, and Jun Zhang
Published February 9, 2012
Synopsis: Floats Like a Pyramid, Physics, APS

"Writing in Physical Review Letters, Bin Liu and co-workers at New York University present results from experiments on an inanimate pyramid-shaped flyer, or “bug.” Their choice of the shape was made in view of previous experiments with tethered flight, which showed that pyramids could hover in an airflow."
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.108.068103

Saturday, February 4, 2012

Another Earth

Astrónomos europeos hallaron un planeta rocoso, como el nuestro que podría contener agua y vida a 22 años luz de la Tierra, en la constelación de Escorpio.

Hallan planeta rocoso que podría contener agua y vida

Wednesday, January 25, 2012

Saturday, January 14, 2012

Get physical

Michael Quinion (World Wide Words) writes
"Have you noticed how physical has begun to be more popular as one element in retronyms relating to the online world? If you actually go into a store to buy something, instead of ordering online, that’s physical shopping. Similarly, a physical book is one made with ink on dead trees, in contrast to a digital e-book. Both terms have been around for more than a decade but my impression is that they’ve only recently gone mainstream."
http://www.worldwidewords.org/nl/yurg.htm

Nano 'ears' for nano whispers

"MOVE over microphones, nanophones have arrived. A gold sphere just 60 nanometres in diameter is the most sensitive listening device ever created, paving the way for soundtracks to formerly silent movies of bacteria and other single-celled organisms.
Alexander Ohlinger at Ludwig Maximilian University in Munich (LMU), Germany, and colleagues suspended gold nanoparticles in a drop of water. They trapped one sphere in a laser beam and then fired rapid pulses of light from a second laser at others a few micrometres away. The pulses heated the nanoparticles, which disturbed the water around them, generating pressure, or sound, waves."
Gold nano 'ears' set to listen in on cells - health - 13 January 2012 - New Scientist

Saturday, January 7, 2012

The Shelter of Candelo

Il ricetto è una struttura fortificata protetta, posta all'interno di un paese, dove si accumulavano i beni (foraggi, vini, etc) della popolazione e, occasionalmente, dove si ritirava la popolazione in caso di attacchi dall'esterno.
http://it.wikipedia.org/wiki/Ricetto_di_Candelo
The The name Ricetto comes form the latin word "Receptum" that, in the Middle ages, simply meant "Shelter".
http://www.unricettoinmusica.it/index.php?en/96/ricetto-of-candelo

The Erbil Citadel

"Erbil Citadel Town, which is situated dramatically on top of an artificial, 32-meters high earthen mound, and visually dominating the expansive modern city of Erbil, is believed to have been in continuous existence for 7000 years or even more. Thus, it may be regarded as the oldest continuously inhabited settlement in the world. Because of its past fortifications and steeply inclined mound, which is at some locations nearly 45 degrees, it has managed to survive numerous sieges and fierce attacks. The existing fabric, however, goes back to several hundred years but is, nevertheless, of extreme vernacular architectural and urban interest, not only for Iraq but also for humanity at large."
http://whc.unesco.org/en/tentativelists/5479/

Friday, January 6, 2012

Megalith Map

An important resource for finding megalithic and prehistoric sites in England, Ireland, Scotland and Wales
http://www.megalithic.co.uk/asb_mapsquare.php

Louisiana's wetlands

Jim Allen is proposing some quite interesting images of the Louisiana's wetlands. Look them at
http://www.atlantisbolivia.org/canalslouisiana1.htm

Ohm's law at atomic scale

"A new technique for embedding atomic-scale wires within crystals of silicon has revealed that Ohm's law can hold true for wires just four atoms thick and one atom tall. The result comes as a surprise because conventional wisdom suggests that quantum effects should cause large deviations from Ohm's law for such tiny wires. Paradoxically, the researchers hope the finding will aid the development of quantum computers."

Ohm's law holds down to atomic scale - physicsworld.com

Thursday, January 5, 2012

Chimeras

"The world's first monkeys to be created from the embryos of several individuals have been born at a US research centre. Scientists at the Oregon National Primate Research Centre produced the animals, known as chimeras, by sticking together between three and six rhesus monkey embryos in the early stages of their development....The first chimeric animals were created by researchers in the 1960s, when experiments with mouse embryos showed they could combine to form a single mouse of normal size. Since then, scientists have created chimeric versions of rats, rabbits, sheep and cattle."
More http://www.guardian.co.uk/science/2012/jan/05/chimera-monkeys-combining-several-embryos

Noah's problems

Quite interesting paper, published in Econometrica, Vol. 66, No. 6 (November, 1998}, 1279-1298.
The tile is: THE NOAH’S ARK PROBLEM, by MARTIN L. WEITZMAN
Abstract: This paper is about the economic theory of biodiversity preservation. A cost-effectiveness methodology is constructed, which results in a particular formula that can be used as a criterion to rank projects. The ranking criterion is sufficiently operational to be useful in suggesting what to look at when determining actual conservation priorities among endangered species. At the same time, the formula is firmly rooted in a mathematically rigorous optimization framework, so that its theoretical underpinnings are clear. The underlying model, called the “Noah‘s Ark Problem,” is intended to be a kind of canonical form that  hones down to its analytical essence the problem of best preserving diversity under a limited budget constraint.
Keywords: Biodiversity, endangered species, diversity theory
The author writes
"There are several motivations for this paper. Essentially, I am trying to introduce an analytical framework that represents a useful way of thinking about the economics of diversity through the medium of an abstract mathematical model. The “Noah’s Ark Problem” is a parable intended to be a kind of canonical form of the simplest possible way of representing how best to preserve biodiversity under a limited budget constraint. Throughout the paper, emphasis is laid upon simplicity of structure, in order to get at the analytical essence of
the problem."
Noah's-ark-problem-pdf

Wednesday, January 4, 2012

Aran Islands

 "On the cliff tops, ancient forts such as Dún Aengus on Inishmór and Dún Chonchúir on Inishmaan are some of the oldest archaeological remains in Ireland. A lacework of ancient stone walls enfolds all three islands to contain local livestock. Also found are early clocháns (dry-stone beehive huts from the early-Christian period). Enda of Aran founded the first true Irish Monastery near Killeany (Cill Éinne or Church of Enda). In time there were a dozen monasteries on Inishmór alone. Many Irish saints had some connection with Aran: St. Brendan was blessed for his voyage there; Jarlath of Tuam, Finnian of Clonard, and St. Columba called it the "Sun of the West."" From  http://en.wikipedia.org/wiki/Aran_Islands



A lacework



Dún Chonchúir on Inishmaan

Megalithic Ireland

Map of Ireland, showing the Counties and historical Provinces
http://www.irishmegaliths.org.uk/iremap.htm
For each county, there is the list of places and images. See for instance:
http://www.irishmegaliths.org.uk/galway.htm