Attractive internal wave patterns

This paper gives background information for the fluid dynamics video on internal wave motion in a trapezoidal tank.Comment: 2 pg, movie at two resolutions _low(Low-resolution) and _hr(High-resolution

Different evolutionary pathways underlie the morphology of wrist bones in hominoids

BACKGROUND The hominoid wrist has been a focus of numerous morphological analyses that aim to better understand long-standing questions about the evolution of human and hominoid hand use. However, these same analyses also suggest various scenarios of complex and mosaic patterns of morphological evolution within the wrist and potentially multiple instances of homoplasy that would benefit from require formal analysis within a phylogenetic context.We identify morphological features that principally characterize primate - and, in particular, hominoid (apes, including humans) - wrist evolution and reveal the rate, process and evolutionary timing of patterns of morphological change on individual branches of the primate tree of life. Linear morphological variables of five wrist bones - the scaphoid, lunate, triquetrum, capitate and hamate - are analyzed in a diverse sample of extant hominoids (12 species, 332 specimens), Old World (8 species, 43 specimens) and New World (4 species, 26 specimens) monkeys, fossil Miocene apes (8 species, 20 specimens) and Plio-Pleistocene hominins (8 species, 18 specimens). RESULT Results reveal a combination of parallel and synapomorphic morphology within haplorrhines, and especially within hominoids, across individual wrist bones. Similar morphology of some wrist bones reflects locomotor behaviour shared between clades (scaphoid, triquetrum and capitate) while others (lunate and hamate) indicate clade-specific synapomorphic morphology. Overall, hominoids show increased variation in wrist bone morphology compared with other primate clades, supporting previous analyses, and demonstrate several occurrences of parallel evolution, particularly between orangutans and hylobatids, and among hominines (extant African apes, humans and fossil hominins). CONCLUSIONS Our analyses indicate that different evolutionary processes can underlie the evolution of a single anatomical unit (the wrist) to produce diversity in functional and morphological adaptations across individual wrist bones. These results exemplify a degree of evolutionary and functional independence across different wrist bones, the potential evolvability of skeletal morphology, and help to contextualize the postcranial mosaicism observed in the hominin fossil record

Attractive internal wave patterns

This paper gives background information for the fluid dynamics video on internal wave motion in a trapezoidal tank.Comment: 2 pg, movie at two resolutions _low(Low-resolution) and _hr(High-resolution

A Study of the Dynamics of Cardiac Ischemia using Experimental and Modeling Approaches

The dynamics of cardiac ischemia was investigated using experimental studies and computer simulations. An experimental model consisting of an isolated and perfused canine heart with full control over blood flow rate to a targeted coronary artery was used in the experimental study and a realistically shaped computer model of a canine heart, incorporating anisotropic conductivity and realistic fiber orientation, was used in the simulation study. The phenomena investigated were: (1) the influence of fiber rotation on the epicardial potentials during ischemia and (2) the effect of conductivity changes during a period of sustained ischemia. Comparison of preliminary experimental and computer simulation results suggest that as the ischemic region grows from the endocardium towards the epicardium, the epicardial potential patterns follow the rotating fiber orientation in the myocardium. Secondly, in the experimental studies it was observed that prolonged ischemia caused a subsequent reduction in the magnitude of epicardial potentials. Similar results were obtained from the computer model when the conductivity of the tissue in the ischemic region was reduce

Electrostatic confinement of electrons in graphene nano-ribbons

Coulomb blockade is observed in a graphene nanoribbon device with a top gate. When two pn junctions are formed via the back gate and the local top gate, electrons are confined between the pn junctions which act as the barriers. When no pn junctions are induced by the gate voltages, electrons are still confined, as a result of strong disorder, but in a larger area. Measurements on five other devices with different dimensions yield consistent results.Comment: 4 figures, 1 table, 4.4page

Magneto-transport through graphene nano-ribbons

We investigate magneto-transport through graphene nano-ribbons as a function of gate and bias voltage, and temperature. We find that a magnetic field systematically leads to an increase of the conductance on a scale of a few tesla. This phenomenon is accompanied by a decrease in the energy scales associated to charging effects, and to hopping processes probed by temperature-dependent measurements. All the observations can be interpreted consistently in terms of strong-localization effects caused by the large disorder present, and exclude that the insulating state observed in nano-ribbons can be explained solely in terms of a true gap between valence and conduction band.Comment: 4 pages, 5 figure

Pheochromocytomas and paragangliomas: from DNA to the daily clinical practice

The neuroendocrine system is a diffuse system in which the nervous system and the hormones of the endocrine glands interact. The neuroendocrine organs of the sympathetic and parasympathetic autonomic nervous system are called paraganglia. These organs usually manifest as anatomically discrete bodies, which derive from the neural crest and produce catecholamines and various peptides. Various localizations of paraganglia in the human body are known, including the adrenal gland, organs of Zuckerkandl, and carotid and aortic bodies. Paraganglia are divided into two functional groups, i.e. the sympathoadrenal and the parasympathetic autonomic nervous system. Sympathetic paraganglia are predominantly located in the prevertebral and paravertebral sympathetic trunks, and along the fibers of the hypogastric plexus, innervating pelvic and retroperitoneal organs. Parasympathetic paraganglia are almost exclusively located in the region of cranial as well as thoracic branches of the of the glossopharyngeal nerves and vagal nerves. The principal glossopharyngeal paraganglia are the tympanic (located in the wall of the middle ear), and the carotid bodies (Figure 1). Neoplasms of the paraganglia are called pheochromocytomas (PCC), sympathetic and parasympathetic paragangliomas. The name PCC is derived from the Greek synonym “dark colored tumor”, because it was first described by Pick as a chromium salt-reactive tumor which lead to dark coloration. PCC are tumors which originate in the adrenal medulla. Sympathetic paragangliomas (sPGL), in the literature often described as extra-adrenal PCC, usually produce catecholamines and occur in the abdominal cavity and the aorticopulmonary bodies, but not in the adrenal medulla. Parasympathetic paragangliomas, also called head and neck paraganglioma, usually do not produce catecholamines and are situated in the wall of the middle ear, along the vagal nerve, and the carotid and jugular bodies. In the literature they are still often referred to as chemodectomas, glomus tumors, or carotid body tumors