564 research outputs found

    Simple geometrical interpretation of the linear character for the Zeno-line and the rectilinear diameter

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    The unified geometrical interpretation of the linear character of the Zeno-line (unit compressibility line Z=1) and the rectilinear diameter is proposed. We show that recent findings about the properties of the Zeno-line and striking correlation with the rectilinear diameter line as well as other empirical relations can be naturally considered as the consequences of the projective isomorphism between the real molecular fluids and the lattice gas (Ising) model.Comment: 7 pages, 2 figure

    Ground Heave Due to Jet Grouting Near an Existing Structure

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    Renovations of the MBTA Copley Station in Boston included construction of a new elevator shaft to improve disabled access to the existing Green Line station. The site is immediately adjacent to the Eastern façade of the historic Old South Church. The construction work required excavation support including a perimeter secant pile wall and a jet-grouted base plug. Significant ground and structural movements were observed during jet grouting, mainly associated with soil displacements during grout injection. A three dimensional numerical model was developed, using the Plaxis 3D Foundationℱ program, in order to test the hypothesis that the observed movements of the structure could be associated with the installation of the jet grout piles. The amount of volume expansion associated with installation of jet grout piles is estimated based by calibrating the model to measured ground movements. The finite element model results give a consistent explanation for the observed pattern of movements, including the heave of the church wall and lateral displacements at inclinometers located within the vicinity of the structure, measured at the time when damage occurred. The model assumes there is a vertical line of weakness in the masonry, representative of a pre-existing structural crack, as observed by structural investigations; and hence, confirms the underlying mechanical hypothesis for the source of ground movements

    25-Hydroxy Vitamin D Deficiency Following Pediatric Hematopoietic Stem Cell Transplant

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    Children may be at increased risk for vitamin D deficiency following HSCT because of lack of sun exposure, the recommended use of sunscreen, dietary insufficiency, malabsorption, and the use of certain medications. We prospectively assessed the prevalence of and risk factors for 25-hydroxy (25-OH) vitamin D deficiency in 67 patients transplanted at our institution. 25-OH vitamin D levels were checked during 3 separate 4-week periods in the spring, autumn, and winter. Subjects were <2 years following transplant and/or being treated for chronic graft-versus-host disease (cGVHD). Levels less than 20 ng/mL were considered deficient, and those less than 30 ng/mL were considered insufficient. The mean 25-OH vitamin D level was 22.8 ng/mL (range: 7-46.2). A total of 80.6% (confidence interval [CI] 69.1%-89.3%) of patients had a level less than the lower limit of the institutional normal range. The deficiency rate was 37.3% (CI 25.8%-50%). The mean parathyroid hormone (PTH) level was 77.5 (SD = 80.5). There was no correlation between 25-OH vitamin D and PTH levels. We evaluated potential risk factors for 25-OH vitamin D deficiency including age, season of testing, sun exposure, sunscreen use, use of steroid or calcineurin inhibitor, race, and dairy intake. In multivariate logistic regression, only older age was found to be a risk factor for deficiency (P = .004). Patients with deficient levels were treated with 50,000 IU of ergocalciferol once weekly for 6 weeks. A postrepletion 25-OH level was available for 22 patients. The majority of repleted patients had a normal posttreatment level (63.6%). The postsupplementation level corrected into the insufficient range for 31.8% of patients and 4.6% remained deficient. Vitamin D insufficiency and deficiency are common following HSCT. Further investigation into potential risk factors and the appropriate supplementation for these patients is warranted

    Language control and parallel recovery of language in individuals with aphasia

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    Background: The causal basis of the different patterns of language recovery following stroke in bilingual speakers is not well understood. Our approach distinguishes the representation of language from the mechanisms involved in its control. Previous studies have suggested that difficulties in language control can explain selective aphasia in one language as well as pathological switching between languages. Here we test the hypothesis that difficulties in managing and resolving competition will also be observed in those who are equally impaired in both their languages even in the absence of pathological switching. Aims: To examine difficulties in language control in bilingual individuals with parallel recovery in aphasia and to compare their performance on different types of conflict task. Methods & procedures: Two right-handed, non-native English-speaking participants who showed parallel recovery of two languages after stroke and a group of non-native English-speaking, bilingual controls described a scene in English and in their first language and completed three explicit conflict tasks. Two of these were verbal conflict tasks: a lexical decision task in English, in which individuals distinguished English words from non-words, and a Stroop task, in English and in their first language. The third conflict task was a non-verbal flanker task. Outcomes & Results: Both participants with aphasia were impaired in the picture description task in English and in their first language but showed different patterns of impairment on the conflict tasks. For the participant with left subcortical damage, conflict was abnormally high during the verbal tasks (lexical decision and Stroop) but not during the non-verbal flanker task. In contrast, for the participant with extensive left parietal damage, conflict was less abnormal during the Stroop task than the flanker or lexical decision task. Conclusions: Our data reveal two distinct control impairments associated with parallel recovery. We stress the need to explore the precise nature of control problems and how control is implemented in order to develop fuller causal accounts of language recovery patterns in bilingual aphasia

    Probability Theory Compatible with the New Conception of Modern Thermodynamics. Economics and Crisis of Debts

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    We show that G\"odel's negative results concerning arithmetic, which date back to the 1930s, and the ancient "sand pile" paradox (known also as "sorites paradox") pose the questions of the use of fuzzy sets and of the effect of a measuring device on the experiment. The consideration of these facts led, in thermodynamics, to a new one-parameter family of ideal gases. In turn, this leads to a new approach to probability theory (including the new notion of independent events). As applied to economics, this gives the correction, based on Friedman's rule, to Irving Fisher's "Main Law of Economics" and enables us to consider the theory of debt crisis.Comment: 48p., 14 figs., 82 refs.; more precise mathematical explanations are added. arXiv admin note: significant text overlap with arXiv:1111.610

    Intraoperative monitoring study of ipsilateral motor evoked potentials in scoliosis surgery

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    Ipsilateral motor evoked potentials (MEPs) in spinal cord surgery intraoperative monitoring is not well studied. We show that ipsilateral MEPs have significantly larger amplitudes and were elicited with lower stimulation intensities than contralateral MEPs. The possible underlying mechanisms are discussed based on current knowledge of corticospinal pathways. Ipsilateral MEPs may provide additional information on the integrity of descending motor tracts during spinal surgery monitoring

    Mathematical Conception of "Phenomenological" Equilibrium Thermodynamics

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    In the paper, the principal aspects of the mathematical theory of equilibrium thermodynamics are distinguished. It is proved that the points of degeneration of a Bose gas of fractal dimension in the momentum space coincide with critical points or real gases, whereas the jumps of critical indices and the Maxwell rule are related to the tunnel generalization of thermodynamics. Semiclassical methods are considered for the tunnel generalization of thermodynamics and also for the second and ultrasecond quantization (operators of creation and annihilation of pairs). To every pure gas there corresponds a new critical point of the limit negative pressure below which the liquid passes to a dispersed state (a foam). Relations for critical points of a homogeneous mixture of pure gases are given in dependence on the concentration of gases.Comment: 37 pages, 9 figure, more precise explanations, more references. arXiv admin note: substantial text overlap with arXiv:1202.525
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