Oceanographic observations at the Amundsen sea shelf break

Introduction: The continental shelf environment of the Amundsen and Bellingshausen seas differs markedly from that of the other circumpolar seas, where water temperatures are close to the surface freezing point throughout. In the Amundsen/Bellingshausen sector near-freezing temperatures are encountered only in the upper few hundred metres of the water column. Below this surface layer a broad thermocline trends towards upper Circumpolar Deep Water (uCDW), which is found in a form that is almost unmodified from its off-shelf manifestation (Giulivi and Jacobs, 1996). This means that the ice shelves of the Amundsen and Bellingshausen seas experience ocean temperatures some three degrees warmer than those experienced by the other Antarctic ice shelves, and the rates of basal melting are correspondingly high (Jacobs et al., 1996)

pH-dependent mechanism of nitric oxide release in nitrophorins 2 and 4

Nitrophorins are NO carrier proteins that transport and release NO through a pH-dependent conformational change. They bind NO tightly in a low pH environment and release it in a higher pH environment. Experimental evidence shows that the increase in the NO dissociation equilibrium constant, K d, is due mainly to an increase in the NO release rate. Structural and kinetic data strongly suggest that NPs control NO escape by modulating its migration from the active site to the solvent through a pH-dependent conformational change. NP2 and NP4 are two representative proteins of the family displaying a 39% overall sequence identity, and interestingly, NP2 releases NO slower than NP4. The proposal that NPs' NO release relies mainly on the NO escape rate makes NPs a very peculiar case among typical heme proteins. The connection between the pH-dependent conformational change and ligand release mechanism is not fully understood and the structural basis for the pH induced structural transition and the different NO release patterns in NPs are unresolved, yet interesting issues. In this work, we have used state of the art molecular dynamics simulations to study the NO escape process in NP2 and NP4 in both the low and high pH states. Our results show that both NPs modulate NO release by switching between a "closed" conformation in a low pH environment and an "open" conformation at higher pH. In both proteins, the change is caused by the differential protonation of a common residue Asp30 in NP4 and Asp29 in NP2, and the NO escape route is conserved. Finally, our results show that, in NP2, the conformational change to the "open" conformation is smaller than that for NP4 which results in a higher barrier for NO release.Fil: Swails, Jason M.. University of Florida; Estados UnidosFil: Meng, Yilin. University of Florida; Estados UnidosFil: Walker, F. Ann. University of Arizona; Estados UnidosFil: Marti, Marcelo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Estrin, Dario Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Roitberg, Adrián. University of Florida; Estados Unido

Neuroacanthocytosis Syndromes

Neuroacanthocytosis (NA) syndromes are a group of genetically defined diseases characterized by the association of red blood cell acanthocytosis and progressive degeneration of the basal ganglia. NA syndromes are exceptionally rare with an estimated prevalence of less than 1 to 5 per 1'000'000 inhabitants for each disorder. The core NA syndromes include autosomal recessive chorea-acanthocytosis and X-linked McLeod syndrome which have a Huntington´s disease-like phenotype consisting of a choreatic movement disorder, psychiatric manifestations and cognitive decline, and additional multi-system features including myopathy and axonal neuropathy. In addition, cardiomyopathy may occur in McLeod syndrome. Acanthocytes are also found in a proportion of patients with autosomal dominant Huntington's disease-like 2, autosomal recessive pantothenate kinase-associated neurodegeneration and several inherited disorders of lipoprotein metabolism, namely abetalipoproteinemia (Bassen-Kornzweig syndrome) and hypobetalipoproteinemia leading to vitamin E malabsorption. The latter disorders are characterized by a peripheral neuropathy and sensory ataxia due to dorsal column degeneration, but movement disorders and cognitive impairment are not present. NA syndromes are caused by disease-specific genetic mutations. The mechanism by which these mutations cause neurodegeneration is not known. The association of the acanthocytic membrane abnormality with selective degeneration of the basal ganglia, however, suggests a common pathogenetic pathway. Laboratory tests include blood smears to detect acanthocytosis and determination of serum creatine kinase. Cerebral magnetic resonance imaging may demonstrate striatal atrophy. Kell and Kx blood group antigens are reduced or absent in McLeod syndrome. Western blot for chorein demonstrates absence of this protein in red blood cells of chorea-acanthocytosis patients. Specific genetic testing is possible in all NA syndromes. Differential diagnoses include Huntington disease and other causes of progressive hyperkinetic movement disorders. There are no curative therapies for NA syndromes. Regular cardiologic studies and avoidance of transfusion complications are mandatory in McLeod syndrome. The hyperkinetic movement disorder may be treated as in Huntington disease. Other symptoms including psychiatric manifestations should be managed in a symptom-oriented manner. NA syndromes have a relentlessly progressive course usually over two to three decades

Protection from uncertainty in the exploration/exploitation trade-off

The exploration/exploitation trade-off (EE trade-off) describes how, when faced with several competing alternatives, decision-makers must often choose between a known good alternative (exploitation) and one or more unknown but potentially more rewarding alternatives (exploration). Prevailing theory on how humans perform the EE trade-off states that uncertainty is a major motivator for exploration: the more uncertain the environment, the more exploration that will occur. The current paper examines whether exploratory behaviour in both choice and attention may be impacted differently depending on whether uncertainty is onset suddenly (unexpected uncertainty), or more slowly (expected uncertainty). It is shown that when uncertainty was expected, participants tended to explore less with their choices, but not their attention, than when it was unexpected. Crucially, the impact of this "protection from uncertainty" on exploration only occurred when participants had an opportunity to learn the structure of the task prior to experiencing uncertainty. This suggests that the interaction between uncertainty and exploration is more nuanced than simply more uncertainty leading to more exploration, and that attention and choice behaviour may index separate aspects of the EE trade-off

Predictors and outcomes of recognition of intellectual disability for adults during hospital admissions : A retrospective data linkage study in NSW, Australia

Adults with intellectual disability have high health care needs. Despite frequent contact with health services, they often receive inadequate health care. One method to improve health care delivery is reasonable adjustments, that is, the adaptation of health care delivery such that barriers to participation are removed for the person with disability. A starting point for the provision of reasonable adjustments is recognition of intellectual disability during the health care contact. To determine rates and predictors of the recognition of intellectual disability during hospital admissions, and its impact on admission metrics, we examined a population of adults with intellectual disability identified from disability services datasets from New South Wales, Australia between 2005 and 2014. Recognition of intellectual disability was determined by the recording of an International Classification of Diseases 10th revision (ICD-10) diagnostic code for intellectual disability during a given hospital admission. We examined how recognition of intellectual disability related to length of hospital episodes. We found an overall low rate of recognition of intellectual disability (23.79%) across all hospital episodes, with the proportion of hospital episodes recognising intellectual disability decreasing from 2005–2015. Admissions for adults with complex health profiles (e.g., those with many comorbidities, those with Autism Spectrum Disorder, and those admitted for urgent treatment) were more likely to recognise intellectual disability, but admissions for adults with complexity in other domains (i.e., for those in custody, or those with drug and alcohol disorders) were less likely to recognise intellectual disability. Recognition of intellectual disability was associated with longer episodes of care, possibly indicating the greater provision of reasonable adjustments. To improve the recognition of intellectual disability for adults during health service contacts, we advocate for the implementation of targeted initiatives (such as a nationwide disability flag to be included in health service records) to improve the provision of reasonable adjustments

The perceived impact of pre-service student teachers on the optimal learning environment of the students they teach and the teachers who mentor them

Doctor of PhilosophyDepartment of Curriculum and InstructionM. Gail ShroyerThis study was designed to examine one component of impact within a High School Professional Development School (PDS) partnership. The purpose of this study was to explore the perceived impact of pre-service teachers on the students they teach and the cooperating teachers who mentor them. More specifically, this study was designed to explore the impact on the learning environment of high school students who were taught by pre-service teachers and the cooperating teachers who mentored them from the perspective of 8 pre-service teachers, 130 high school students, and 8 cooperating teachers. The theoretical framework for this study was based on the concept of an Optimal Learning Environment (National Research Council, 1999). The overarching question for this study was: In what ways do pre-service teachers impact the learning environment of the PDS in which they complete their final clinical experience? Survey and interview data were gathered from participants to explore the perceived impact of the pre-service teachers on the (a) learner centered learning environment, (b) assessment centered learning environment, and (c) knowledge centered learning environment of the high school students and cooperating mentor teachers. The data collected were focused on what the high school students, pre-service teachers and cooperating mentor teachers perceived based on their personal experiences and understanding. The results of this study indicated a perceived positive impact on the learner centered, assessment centered, and knowledge centered learning environments of the high school students and the cooperating mentor teachers from the perspectives of the high school students, pre-service teachers and cooperating mentor teachers. The researcher thus concluded that the pre-service teachers positively impacted the perceived Optimal Learning Environment of the PDS in which they completed their final clinical experience

Gapless spin-liquid state in the structurally disorder-free triangular antiferromagnet NaYbO2_2

We present the structural characterization and low-temperature magnetism of the triangular-lattice delafossite NaYbO$_2$. Synchrotron x-ray diffraction and neutron scattering exclude both structural disorder and crystal-electric-field randomness, whereas heat-capacity measurements and muon spectroscopy reveal the absence of magnetic order and persistent spin dynamics down to at least 70\,mK. Continuous magnetic excitations with the low-energy spectral weight accumulating at the $K$-point of the Brillouin zone indicate the formation of a novel spin-liquid phase in a triangular antiferromagnet. This phase is gapless and shows a non-trivial evolution of the low-temperature specific heat. Our work demonstrates that NaYbO$_2$ practically gives the most direct experimental access to the spin-liquid physics of triangular antiferromagnets.Comment: 6 pages, 4figure