Comparative Brain Morphology of the Greenland and Pacific Sleeper Sharks and its Functional Implications

In cartilaginous fishes, variability in the size of the brain and its major regions is often associated with primary habitat and/or specific behavior patterns, which may allow for predictions on the relative importance of different sensory modalities. The Greenland (Somniosus microcephalus) and Pacific sleeper (S. pacificus) sharks are the only non-lamnid shark species found in the Arctic and are among the longest living vertebrates ever described. Despite a presumed visual impairment caused by the regular presence of parasitic ocular lesions, coupled with the fact that locomotory muscle power is often depressed at cold temperatures, these sharks remain capable of capturing active prey, including pinnipeds. Using magnetic resonance imaging (MRI), brain organization of S. microcephalus and S. pacificus was assessed in the context of up to 117 other cartilaginous fish species, using phylogenetic comparative techniques. Notably, the region of the brain responsible for motor control (cerebellum) is small and lacking foliation, a characteristic not yet described for any other large-bodied (\u3e3 m) shark. Further, the development of the optic tectum is relatively reduced, while olfactory brain regions are among the largest of any shark species described to date, suggestive of an olfactory-mediated rather than a visually-mediated lifestyle

Rheo-PIV of a shear-banding wormlike micellar solution under large amplitude oscillatory shear

We explore the behavior of a wormlike micellar solution under both steady and large amplitude oscillatory shear (LAOS) in a cone–plate geometry through simultaneous bulk rheometry and localized velocimetric measurements. First, particle image velocimetry is used to show that the shear-banded profiles observed in steady shear are in qualitative agreement with previous results for flow in the cone–plate geometry. Then under LAOS, we observe the onset of shear-banded flow in the fluid as it is progressively deformed into the non-linear regime—this onset closely coincides with the appearance of higher harmonics in the periodic stress signal measured by the rheometer. These harmonics are quantified using the higher-order elastic and viscous Chebyshev coefficients e [subscript n] and v [subscript n] , which are shown to grow as the banding behavior becomes more pronounced. The high resolution of the velocimetric imaging system enables spatiotemporal variations in the structure of the banded flow to be observed in great detail. Specifically, we observe that at large strain amplitudes (γ [subscript 0] ≥ 1), the fluid exhibits a three-banded velocity profile with a high shear rate band located in-between two lower shear rate bands adjacent to each wall. This band persists over the full cycle of the oscillation, resulting in no phase lag being observed between the appearance of the band and the driving strain amplitude. In addition to the kinematic measurements of shear banding, the methods used to prevent wall slip and edge irregularities are discussed in detail, and these methods are shown to have a measurable effect on the stability boundaries of the shear-banded flow.Spain. Ministerio de Educación y Ciencia (MEC) (Project FIS2010-21924-C02-02

Sensory Input Pathways and Mechanisms in Swallowing: A Review

Over the past 20 years, research on the physiology of swallowing has confirmed that the oropharyngeal swallowing process can be modulated, both volitionally and in response to different sensory stimuli. In this review we identify what is known regarding the sensory pathways and mechanisms that are now thought to influence swallowing motor control and evoke its response. By synthesizing the current state of research evidence and knowledge, we identify continuing gaps in our knowledge of these mechanisms and pose questions for future research

A consensus protocol for functional connectivity analysis in the rat brain

Task-free functional connectivity in animal models provides an experimental framework to examine connectivity phenomena under controlled conditions and allows for comparisons with data modalities collected under invasive or terminal procedures. Currently, animal acquisitions are performed with varying protocols and analyses that hamper result comparison and integration. Here we introduce StandardRat, a consensus rat functional magnetic resonance imaging acquisition protocol tested across 20 centers. To develop this protocol with optimized acquisition and processing parameters, we initially aggregated 65 functional imaging datasets acquired from rats across 46 centers. We developed a reproducible pipeline for analyzing rat data acquired with diverse protocols and determined experimental and processing parameters associated with the robust detection of functional connectivity across centers. We show that the standardized protocol enhances biologically plausible functional connectivity patterns relative to previous acquisitions. The protocol and processing pipeline described here is openly shared with the neuroimaging community to promote interoperability and cooperation toward tackling the most important challenges in neuroscience

Long-term results of surgery for active infective endocarditis

This paper was undertaken to determine the long-term outcome of active infective endocarditis treated with antibiotic and radical excision of infected tissues by surgery. From October 1978 to August 1994, 122 consecutive patients were operated on during the acute phase of infective endocarditis. There were 85 men and 37 women whose mean age was 50 years, ranging from 20 to 79. Surgery was needed because of one or more of the following complications: cardiogenic/septic shock in 19 patients, congestive heart failure in 68, persistent sepsis in 64, peripheral embolization in 20, and cerebral embolization in 10. The offending microorganism was identified in 110 patients, staphylococci were the most common ones. Seventy-six patients had native valve endocarditis and 46 had prosthetic valve endocarditis. Simple valve replacement or repair was performed in 60 patients and radical resection of the valve and surrounding tissues with reconstruction of the heart with either fresh autologous pericardium or glutaraldehyde-fixed bovine pericardium was performed in 62 with paravalvular abscess. Pulmonary autograft and aortic homograft were used in only three patients, the remaining patients had either bioprostheses or mechanical heart valves if valve repair was not feasible. There were nine deaths, for an operative mortality of 7.4%. Logistic regression analysis identified preoperative shock and renal failure as predictors of operative mortality. Operative survivors were followed up from 4 to 173 months, mean of 56.4. The actuarial survival at 10 years was 61 +/- 6%. Logistic regression analysis identified preoperative New York Heart Association functional class IV and perioperative renal failure as predictors of late mortality. Eight patients developed recurrent endocarditis 10-102 months postoperatively. The freedom from recurrent endocarditis at 10 years was 79 +/- 9%. All patients who developed this late complication had paravalvular abscess at the time of original operation. These data suggest that surgery for active infective endocarditis yield a high probability of eradicating the infection with relatively low operative mortality and good long-term results