Lesiones traumáticas de la columna vertebral en niños

—Se ha realizado un estudio retrospectivo de los casos de traumatismo raquídeo atendidos en urgencias de nuestro centro desde 1987 hasta 1995. Del total de 159.202 niños atendidos en dicho período, el 1,8% sufría algún tipo de patología traumática de la columna, de los cuales requirieron ingreso 45 casos. Se analizan la distribución por edad, los factores etiológicos y la localización de la lesión. En 4 casos existió afectación neurológica, 2 de ellos con paraplejía completa. Los traumatismos del raquis en el niño son lesiones poco frecuentes, siendo aún más rara la afectación neurológica. fin nuestra serie el grupo más afectado fueron varones de 8 a 13 años de edad. El tratamiento conservador generalmente da resultados satisfactorios, recurriendo a la cirugía sólo en casos de severa inestabilidad o compromiso neurológico.We report the results of a restrospective study of cases with spinal trauma in children treated in our institution from 1987 until 1995. From 159,202 children under fourteen, only in 1.8% spinal traumatism was present being necessary hospitalization in 45 cases. We analized age distribution, etiologic factors, and level of the lesion. In four patients a neurologic deficit was present, two of them had complete paraplegia. Pediatric spinal trauma is a rare lesion, and associated neurologic deficit is still less common. In our scries, the most affected group was boys, from 8 to 13. Usually conservative treatment provides satisfactory results. Surgery is required only when severe unstability or neurologic deficit are present

Almost commuting self-adjoint matrices --- the real and self-dual cases

We show that a pair of almost commuting self-adjoint, symmetric matrices is close to a pair of commuting self-adjoint, symmetric matrices (in a uniform way). Moreover we prove that the same holds with self-dual in place of symmetric. The notion of self-dual Hermitian matrices is important in physics when studying fermionic systems that have time reversal symmetry. Since a symmetric, self-adjoint matrix is real, we get a real version of Huaxin Lin's famous theorem on almost commuting matrices. Similarly the self-dual case gives a version for matrices over the quaternions. We prove analogous results for element of real C^*-algebras of "low rank." In particular, these stronger results apply to paths of almost commuting Hermitian matrices that are real or self-dual. Along the way we develop a theory of semiprojectivity for real C^*-algebras.Comment: Expanded references. 33 page

Observation of anomalous decoherence effect in a quantum bath at room temperature

Decoherence of quantum objects is critical to modern quantum sciences and technologies. It is generally believed that stronger noises cause faster decoherence. Strikingly, recent theoretical research discovers the opposite case for spins in quantum baths. Here we report experimental observation of the anomalous decoherence effect for the electron spin-1 of a nitrogen-vacancy centre in high-purity diamond at room temperature. We demonstrate that under dynamical decoupling, the double-transition can have longer coherence time than the single-transition, even though the former couples to the nuclear spin bath as twice strongly as the latter does. The excellent agreement between the experimental and the theoretical results confirms the controllability of the weakly coupled nuclear spins in the bath, which is useful in quantum information processing and quantum metrology.Comment: 22 pages, related paper at http://arxiv.org/abs/1102.557

Municipal water quantities and health in Nunavut households: an exploratory case study in Coral Harbour, Nunavut, Canada

Background: Access to adequate quantities of water has a protective effect on human health and well-being. Despite this, public health research and interventions are frequently focused solely on water quality, and international standards for domestic water supply minimums are often overlooked or unspecified. This trend is evident in Inuit and other Arctic communities even though numerous transmissible diseases and bacterium infections associated with inadequate domestic water quantities are prevalent. Objectives: Our objective was to explore the pathways by which the trucked water distribution systems being used in remote northern communities are impacting health at the household level, with consideration given to the underlying social and environmental determinants shaping health in the region. Methods: Using a qualitative case study design, we conducted 37 interviews (28 residents, 9 key informants) and a review of government water documents to investigate water usage practices and perspectives. These data were thematically analysed to understand potential health risks in Arctic communities and households. Results: Each resident receives an average of 110 litres of municipal water per day. Fifteen of 28 households reported experiencing water shortages at least once per month. Of those 15, most were larger households (5 people or more) with standard sized water storage tanks. Water shortages and service interruptions limit the ability of some households to adhere to public health advice. The households most resilient, or able to cope with domestic water supply shortages, were those capable of retrieving their own drinking water directly from lake and river sources. Residents with extended family and neighbours, whom they can rely on during shortages, were also less vulnerable to municipal water delays. Conclusions: The relatively low in-home water quantities observed in Coral Harbour, Nunavut, appear adequate for some families. Those living in overcrowded households, however, are accessing water in quantities more typically seen in water insecure developing countries. We recommend several practical interventions and revisions to municipal water supply systems

"Closing-in" phenomenon in Alzheimer's disease and subcortical vascular dementia

BACKGROUND: The 'closing-in' phenomenon is defined as a tendency to close in on a model while copying it. This is one of several constructional apraxia observed in dementia, particularly in Alzheimer's disease (AD). The aim of this study was to investigate the usefulness of it in the differential diagnosis of AD and subcortical vascular dementia (SVD) and to clarify the factors associated with it. METHODS: We operationally defined and classified it into three types, namely overlap, adherent, and near type. We analyzed the incidence of it in patients with AD (n = 98) and SVD (n = 48). RESULTS: AD patients exhibited a significantly higher occurrence of it as compared to SVD patients. Among the different types of it, the overlap and adherent types occurred almost exclusively in AD patients. A discriminant analysis in AD subjects revealed that the scores obtained from the MMSE, CDR, Barthel index, and the Rey-Osterrieth complex figure test were correlated significantly with the occurrence of it. There was no statistical difference between the Q-EEG parameters of patients that exhibited the closing-in phenomenon and those that did not. CONCLUSIONS: This study suggests that the closing-in phenomenon is phase- and AD-specific and might be a useful tool for the differential diagnosis of AD and SVD

A first estimate of triply heavy baryon masses from the pNRQCD perturbative static potential

Within pNRQCD we compute the masses of spin-averaged triply heavy baryons using the now-available NNLO pNRQCD potentials and three-body variational approach. We focus in particular on the role of the purely three-body interaction in perturbation theory. This we find to be reasonably small and of the order 25 MeV Our prediction for the Omega_ccc baryon mass is 4900(250) in keeping with other approaches. We propose to search for this hitherto unobserved state at B factories by examining the end point of the recoil spectrum against triple charm.Comment: 18 figures, 21 page

Using Land-Based Surveys to Assess Sea Duck Abundance and Behavior in Nearshore Waters of Southern New England, USA

Nearshore waters provide very important habitat for sea ducks (Tribe Mergini) during migration and winter, but gathering information on sea duck use of shallow nearshore waters is challenging because traditional aerial and boat-based surveys are expensive, are usually conducted infrequently, and are often not feasible near the coast. The objective of this study was to use land-based surveys to characterize spatiotemporal variation in the abundance and behavior (e.g., foraging, flying) of Common Eider (Somateria mollissima) and scoters (Melanitta spp.) in nearshore waters of southern New England. Surveys (60–120 min per survey, n = 1,044 surveys) were conducted throughout the day from February 2009 to July 2010 to assess diurnal and seasonal variation in sea duck behavior and spatial distribution at nine sites in southern Rhode Island. The density of sea ducks resting or foraging on the water exhibited little diurnal variation, whereas flight activity dramatically increased nearer to sunrise. Sea duck densities and passage rates (individuals/km2/hr) peaked during migration periods from October through November and February through April, although there were important seasonal differences between sites. For example, the highest densities of Common Eider during fall were in a protected estuary, whereas abundance of scoters during fall was greater at a coastal headland. The relative activity of Common Eider on the water and in flight was similar among sites, whereas scoters exhibited highly variable activity among sites, particularly during winter and spring. The spatiotemporal patterns in abundance and behavior of sea ducks in nearshore waters that we detected using land-based surveys provides essential, complementary information to that available from other types of waterfowl and seabird surveys in southern New England

Sixty Years of Modern Human Origins in the American Anthropological Association

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65197/1/aa.2003.105.1.89.pd

Equivalence of Conventionally-Derived and Parthenote-Derived Human Embryonic Stem Cells

As human embryonic stem cell (hESC) lines can be derived via multiple means, it is important to determine particular characteristics of individual lines that may dictate the applications to which they are best suited. The objective of this work was to determine points of equivalence and differences between conventionally-derived hESC and parthenote-derived hESC lines (phESC) in the undifferentiated state and during neural differentiation.hESC and phESC were exposed to the same expansion conditions and subsequent neural and retinal pigmented epithelium (RPE) differentiation protocols. Growth rates and gross morphology were recorded during expansion. RTPCR for developmentally relevant genes and global DNA methylation profiling were used to compare gene expression and epigenetic characteristics. Parthenote lines proliferated more slowly than conventional hESC lines and yielded lower quantities of less mature differentiated cells in a neural progenitor cell (NPC) differentiation protocol. However, the cell lines performed similarly in a RPE differentiation protocol. The DNA methylation analysis showed similar general profiles, but the two cell types differed in methylation of imprinted genes. There were no major differences in gene expression between the lines before differentiation, but when differentiated into NPCs, the two cell types differed in expression of extracellular matrix (ECM) genes.These data show that hESC and phESC are similar in the undifferentiated state, and both cell types are capable of differentiation along neural lineages. The differences between the cell types, in proliferation and extent of differentiation, may be linked, in part, to the observed differences in ECM synthesis and methylation of imprinted genes