3,151 research outputs found
Comparison of musculoskeletal networks of the primate forelimb
Anatomical network analysis is a framework for quantitatively characterizing the topological organization of anatomical structures, thus providing a way to compare structural integration and modularity among species. Here we apply this approach to study the macroevolution of the forelimb in primates, a structure whose proportions and functions vary widely within this group. We analyzed musculoskeletal network models in 22 genera, including members of all major extant primate groups and three outgroup taxa, after an extensive literature survey and dissections. The modules of the proximal limb are largely similar among taxa, but those of the distal limb show substantial variation. Some network parameters are similar within phylogenetic groups (e.g., non-primates, strepsirrhines, New World monkeys, and hominoids). Reorganization of the modules in the hominoid hand compared to other primates may relate to functional changes such as coordination of individual digit movements, increased pronation/supination, and knuckle-walking. Surprisingly, humans are one of the few taxa we studied in which the thumb musculoskeletal structures do not form an independent anatomical module. This difference may be caused by the loss in humans of some intrinsic muscles associated with the digits or the acquisition of additional muscles that integrate the thumb more closely with surrounding structures
- CAMBIO DE RÉGIMEN Y SOSTENIBILIDAD A LARGO PLAZO DE LA POLÍTICA FISCAL: EL CASO DE ESPAÑA
In this paper, the Spanish fiscal policy sustainability is tested for the period 1964-1996. The theoretical framework used in this paper draws from Quintos (1995) where a distinction between weak and strong conditions for deficit sustainability is pointed out. From an empirical point of view, new cointegration techniques allowing for structural breaks in the long-run relationships as well as in the cointegration parameters are implemented in order to reach a deeper insight. En este trabajo se contrasta la sostenibilidad de la política fiscal en la economía española para el periodo 1964-1996 utilizando el planteamiento teórico propuesto en Quintos (1995). Desde el punto de vista empírico, la novedad del estudio radica en la utilización de nuevas técnicas de cointegración que recogen la posibilidad de cambios estructurales, tanto en las relaciones de largo plazo como en los parámetros de cointegración.sostenibilidad, política fiscal, cointegración, cambio de régimen sustainability, fiscal policy, cointegration, regimen shifts.
¿Qué estudios universitarios de ciencia y tecnología prefieren las mujeres?
Se han utilizado datos de las Pruebas de Acceso a la Universidad realizadas entre 2010 y 2012 en la Universidad de Valencia para analizar el número de mujeres que cursan las diferentes modalidades de Bachillerato, así como las que acceden a titulaciones universitarias ofrecidas por esta universidad de las diferentes áreas del conocimiento tras cursar la modalidad de Bachillerato de "Ciencias y Tecnología", y en particular el número de mujeres en cada una de las titulaciones de "Ciencias", "Ingenierías" y "Ciencias de la Salud". Un 10.2% del alumnado que cursa la modalidad de Bachillerato de "Ciencias y Tecnología" son mujeres que abandonan estas disciplinas para cursar titulaciones de "Ciencias Sociales y Jurídicas" y "Artes y Humanidades". La mayoría de las mujeres que eligen titulaciones de Ciencias y Tecnología prefieren las de "Ciencias de la Salud", siendo una minoría las que eligen titulaciones de "Ingenierías"
Entanglement in fermionic chains with finite range coupling and broken symmetries
We obtain a formula for the determinant of a block Toeplitz matrix associated
with a quadratic fermionic chain with complex coupling. Such couplings break
reflection symmetry and/or charge conjugation symmetry. We then apply this
formula to compute the Renyi entropy of a partial observation to a subsystem
consisting of contiguous sites in the limit of large . The present work
generalizes similar results due to Its, Jin, Korepin and Its, Mezzadri, Mo. A
striking new feature of our formula for the entanglement entropy is the
appearance of a term scaling with the logarithm of the size of . This
logarithmic behaviour originates from certain discontinuities in the symbol of
the block Toeplitz matrix. Equipped with this formula we analyse the
entanglement entropy of a Dzyaloshinski-Moriya spin chain and a Kitaev
fermionic chain with long range pairing.Comment: 27 pages, 5 figure
First anatomical network analysis of fore- and hindlimb musculoskeletal modularity in bonobos, common chimpanzees, and humans
Studies of morphological integration and modularity, and of anatomical complexity in human evolution typically focus on skeletal tissues. Here we provide the first network analysis of the musculoskeletal anatomy of both the fore- and hindlimbs of the two species of chimpanzee and humans. Contra long-accepted ideas, network analysis reveals that the hindlimb displays a pattern opposite to that of the forelimb: Pan big toe is typically seen as more independently mobile, but humans are actually the ones that have a separate module exclusively related to its movements. Different fore- vs hindlimb patterns are also seen for anatomical network complexity (i.e., complexity in the arrangement of bones and muscles). For instance, the human hindlimb is as complex as that of chimpanzees but the human forelimb is less complex than in Pan. Importantly, in contrast to the analysis of morphological integration using morphometric approaches, network analyses do not support the prediction that forelimb and hindlimb are more dissimilar in species with functionally divergent limbs such as bipedal humans
On the M\"obius transformation in the entanglement entropy of fermionic chains
There is an intimate relation between entanglement entropy and Riemann
surfaces. This fact is explicitly noticed for the case of quadratic fermionic
Hamiltonians with finite range couplings. After recollecting this fact, we make
a comprehensive analysis of the action of the M\"obius transformations on the
Riemann surface. We are then able to uncover the origin of some symmetries and
dualities of the entanglement entropy already noticed recently in the
literature. These results give further support for the use of entanglement
entropy to analyse phase transition.Comment: 29 pages, 5 figures. Final version published in JSTAT. Two new
figures. Some comments and references added. Typos correcte
Characterization of a two-transmon processor with individual single-shot qubit readout
We report the characterization of a two-qubit processor implemented with two
capacitively coupled tunable superconducting qubits of the transmon type, each
qubit having its own non-destructive single-shot readout. The fixed capacitive
coupling yields the \sqrt{iSWAP} two-qubit gate for a suitable interaction
time. We reconstruct by state tomography the coherent dynamics of the two-bit
register as a function of the interaction time, observe a violation of the Bell
inequality by 22 standard deviations after correcting readout errors, and
measure by quantum process tomography a gate fidelity of 90%
A MEMS-based solid propellant microthruster array for space and military applications
Since combustion is an easy way to achieve large quantities of energy from a small volume, we developed a MEMS based solid propellant microthruster array for small spacecraft and micro-air-vehicle applications. A thruster is composed of a fuel chamber layer, a top-side igniter with a micromachined nozzle in the same silicon layer. Layers are assembled by adhesive bonding to give final MEMS array. The thrust force is generated by the combustion of propellant stored in a few millimeter cube chamber. The micro-igniter is a polysilicon resistor deposited on a low stress SiO2/SiNx thin membrane to ensure a good heat transfer to the propellant and thus a low electric power consumption. A large range of thrust force is obtained simply by varying chamber and nozzle geometry parameters in one step of Deep Reactive Ion Etching (DRIE). Experimental tests of ignition and combustion employing home made (DB+x% BP) propellant composed of a Double-Base and Black-Powder. A temperature of 250 therefore degrees C, enough to propellant initiation, is reached for 40 mW of electric power. A combustion rate of about 3.4 mm/s is measured for DB+20% BP propellant and thrust ranges between 0.1 and 3,5 mN are obtained for BP ratio between 10% and 30% using a microthruster of 100 mu m of throat wide
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