674 research outputs found
Numerical Modelling of Caseless Ammunition with Coreless Bullet in Internal Ballistics
In the search of a new weapon for combat in short range, it is proposed the use of a new experimentally designed 7.62 mm calibre ammunition with a lighter weight (caseless-coreless). This can be used in carbine assault rifles with short barrel or pistols. In this work, the compressible gases flowing through the gun barrel caused by the proposed ammunition were experimentally and numerically analysed. The Large Eddy Simulation was used for the numerical simulation, considering a compressible and turbulent flow, with the chemical species transport model and a complete conversion of the propellant reaction. Variations in pressure and temperature were compared with the results obtained from a conventional 7.62 mm full metal jacket (FMJ) ammunition. Results of ballistic experimental tests and numerical simulations were similar than those of the 9 mm x 19 mm FMJ ammunitions, showing feasibility for the development of new weapons intended for operations of short range shots.Defence Science Journal, Vol. 65, No. 3, May 2015, pp.203-207, DOI: http://dx.doi.org/10.14429/dsj.65.851
Metodología aplicada en el cálculo de la incertidumbre de medición
En el presente artículo se explican cada una de las etapas que se deben seguir cuando se desea realizar el cálculo de una incertidumbre de medida tal como lo indica la Guía Técnica Colombiana GTC 51 [1]. Además se muestra un ejemplo de aplicación que permite observar de manera práctica la forma de obtener la incertidumbre de una medició
Metodología aplicada en el cálculo de la incertidumbre de medición
En el presente artículo se explican cada una de las etapas que se deben seguir cuando se desea realizar el cálculo de una incertidumbre de medida tal como lo indica la Guía Técnica Colombiana GTC 51 [1]. Además se muestra un ejemplo de aplicación que permite observar de manera práctica la forma de obtener la incertidumbre de una medició
Effect of alkali/mixed alkali metal ions on the thermal and spectralcharacteristics of Dy3+:B2O3-PbO-Al2O3-ZnO glasses
Thermal and spectroscopic features of 50 B2O3–10 PbO–10 Al2O3–10 ZnO–(x) Li2O–(y) Na2O–(z) K2O–1.0 Dy2O3 (mol %) (x = 19, y = 0, and z = 0; x = 0, y = 19, and z = 0; x = 0, y = 0, and z = 19; x = 9.5, y = 9.5, and z = 0; x = 9.5, y = 0, and z = 9.5; x = 0, y = 9.5, and z = 9.5) glasses, that were fabricated by utilizing melt-quenching approach, are investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), optical absorption, photoluminescence excitation (PLE), photoluminescence (PL), and PL decay lifetimes. PL spectra for all the Dy3 +-doped samples show emission bands at 453 nm (blue), 482 nm (blue), 573 nm (yellow), 662 nm (red), and 752 nm (red) corresponding to the 4I15/2 → 6H15/2, 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2, and 4F9/2 → 6H9/2 transitions, respectively, upon excitation at 350 nm. Here, Dy3 +: Li–Na glass shows the highest PL intensity for all identified emissions. The yellow-to-blue (Y/B) emission intensity ratio (varied within the range 1.257–1.376), CIE chromaticity coordinates (x,y) (slight variation between (0.3410, 0.3802) and (0.3495, 0.3872), and correlated color temperatures (CCTs) (changed from 4953 K to 5212 K) are calculated following the PL spectra. Dy3 +: 4F9/2 decay curves show non-exponential behavior and are fitted by the Inokuti-Hirayama (I–H) model, where S = 6 shows best fit, indicating dipole-dipole (d-d) interactions for Dy3 + excited (donor) and ground state (acceptor) ions
Study protocol: improving cognition in people with progressive multiple sclerosis: a multi-arm, randomized, blinded, sham-controlled trial of cognitive rehabilitation and aerobic exercise (COGEx)
Background: Cognitive dysfunction affects up to 70% of people with progressive MS (PMS). It can exert a deleterious effect on activities of daily living, employment and relationships. Preliminary evidence suggests that performance can improve with cognitive rehabilitation (CR) and aerobic exercise (EX), but existing data are predominantly from people with relapsing-remitting MS without cognitive impairment. There is therefore a need to investigate whether this is also the case in people with progressive forms of the disease who have objectively identified cognitive impairment. It is hypothesized that CR and EX are effective treatments for people with PMS who have cognitive impairment, in particular processing speed (PS) deficits, and that a combination of these two treatments is more effective than each individual treatment given alone. We further hypothesize that improvements in PS will be associated with modifications of functional and/or structural plasticity within specific brain networks/regions involved in PS measured with advanced MRI techniques. Methods: This study is a multisite, randomized, double-blinded, sham controlled clinical trial of CR and aerobic exercise. Three hundred and sixty subjects from 11 sites will be randomly assigned into one of four groups: CR plus aerobic exercise; CR plus sham exercise; CR sham plus aerobic exercise and CR sham plus sham exercise. Subjects will participate in the assigned treatments for 12 weeks, twice a week. All subjects will have a cognitive and physical assessment at baseline, 12 weeks and 24 weeks. In an embedded sub-study, approximately 30% of subjects will undergo structural and functional MRI to investigate the neural mechanisms underlying the behavioral response. The primary outcome is the Symbol Digit Modalities Test (SDMT) measuring PS. Secondary outcome measures include: indices of verbal and non-verbal memory, depression, walking speed and a dual cognitive-motor task and MRI. Discussion: The study is being undertaken in 6 countries (11 centres) in multiple languages (English, Italian, Danish, Dutch); with testing material validated and standardized in these languages. The rationale for this approach is to obtain a robustly powered sample size and to demonstrate that these two interventions can be given effectively in multiple countries and in different languages. Trial registration: The trial was registered on September 20th 2018 at www.clinicaltrials.gov having identifier NCT03679468. Registration was performed before recruitment was initiated
Novel erythropoiesis stimulating protein (NESP) for the treatment of anaemia of chronic disease associated with cancer
Anaemia is a common haematologic disorder in patients with cancer and has a multifactorial aetiology, including the effects of the malignancy itself and residual effects from previous therapy. Novel erythropoiesis stimulating protein (NESP, darbepoetin alfa), a protein with additional sialic acid compared with erythropoietin (EPO), stimulates erythropoiesis by the same mechanism as recombinant human erythropoietin (rHuEPO) but it is biochemically distinct. NESP, with its approximately 3-fold greater serum half-life, can maintain haemoglobin levels as effectively as rHuEPO in anaemic patients with chronic renal failure and do so with less frequent dosing. We investigated the ability of NESP to safely increase haemoglobin levels of anaemic patients with non-myeloid malignancies not receiving chemotherapy. NESP was administered under the supervision of a physician at doses of 0.5, 1.0, 2.25 or 4.5 mcg kg−1wk−1for a maximum of 12 weeks. This report includes 89 patients completing the study by November 2000. NESP was well tolerated, with no reported dose-limiting toxicities or treatment-related severe adverse events. Increasing doses of NESP corresponded with increased efficacy. The percentage (95% confidence interval) of patients responding ranged from 61% (42%, 77%) in the 1.0 mcg kg−1wk−1group to 83% (65%, 94%) in the 4.5 mcg kg−1wk−1group. © 2001 Cance Cancer Research Campaig
Improving Phase Change Memory Performance with Data Content Aware Access
A prominent characteristic of write operation in Phase-Change Memory (PCM) is
that its latency and energy are sensitive to the data to be written as well as
the content that is overwritten. We observe that overwriting unknown memory
content can incur significantly higher latency and energy compared to
overwriting known all-zeros or all-ones content. This is because all-zeros or
all-ones content is overwritten by programming the PCM cells only in one
direction, i.e., using either SET or RESET operations, not both. In this paper,
we propose data content aware PCM writes (DATACON), a new mechanism that
reduces the latency and energy of PCM writes by redirecting these requests to
overwrite memory locations containing all-zeros or all-ones. DATACON operates
in three steps. First, it estimates how much a PCM write access would benefit
from overwriting known content (e.g., all-zeros, or all-ones) by
comprehensively considering the number of set bits in the data to be written,
and the energy-latency trade-offs for SET and RESET operations in PCM. Second,
it translates the write address to a physical address within memory that
contains the best type of content to overwrite, and records this translation in
a table for future accesses. We exploit data access locality in workloads to
minimize the address translation overhead. Third, it re-initializes unused
memory locations with known all-zeros or all-ones content in a manner that does
not interfere with regular read and write accesses. DATACON overwrites unknown
content only when it is absolutely necessary to do so. We evaluate DATACON with
workloads from state-of-the-art machine learning applications, SPEC CPU2017,
and NAS Parallel Benchmarks. Results demonstrate that DATACON significantly
improves system performance and memory system energy consumption compared to
the best of performance-oriented state-of-the-art techniques.Comment: 18 pages, 21 figures, accepted at ACM SIGPLAN International Symposium
on Memory Management (ISMM
An update on site search activities for SWGO
The Southern Wide-field Gamma-ray Observatory (SWGO) is a project by
scientists and engineers from 14 countries and 78 institutions to design and
build the first wide-field, ground-based gamma-ray observatory in the Southern
Hemisphere, with high duty cycle and covering an energy range rom hundreds of
GeV to the PeV scale. The observatory will cover the Southern sky and aims to
map the Galaxy's large-scale emission, as well as detecting transient and
variable phenomena. The host sites under consideration are at a minimum
altitude of 4400 m.a.s.l. and comprise two types: flat plateaus of at least 1
km for the installation of an array of tank-based water Cherenkov
detectors (WCD), or large natural lakes for the direct deployment of WCD units.
Four South American countries proposed excellent sites to host the observatory
meeting these requirements. Argentina proposed two locations in the Salta
province, Bolivia presented one site in Chacaltaya, Chile two locations within
the Atacama Astronomical Park, and Peru two ground-based locations in the
Arequipa district as well as lakes in the Cuzco region. The SWGO collaboration
is currently conducting a site characterization study, gathering all the
necessary information for site shortlisting and final site selection by the end
of 2023. The process has reached the shortlisting phase, in which primary and
backup sites for each country have been identified. The primary sites were
visited by a team of experts from the collaboration, to investigate and
validate the proposed site characteristics. Here we present an update on these
site selection activities.Comment: In Proceedings of the 2023 ICRC, Nagoya, Japa
Dependencia funcional, deterioro cognitivo y características de la marcha en adultos mayores con enfermedades crónicas
Objetivo: Identificar el nivel y relación de dependencia funcional (DF), deterioro cognitivo (DC) y características de la marcha en adultos mayores (AM) con enfermedades crónicas, habitantes del área metropolitana de Saltillo, Coahuila.
Método: Diseño descriptivo correlacional. Muestra constituida por 105 AM de 60 años o más, usuarios de los Centros de Atención e Integración Familiar (CAIF). El tamaño de la muestra se determinó a través del paquete estadístico nQuery Advisor 7.0 considerando análisis de correlación bivariada, nivel de significancia de 0.5 y potencia del 95%. El muestreo fue por conveniencia. La recolección de datos se realizó a través de una cédula de datos socio-demográficas conjuntamente con cuatro instrumentos: para DF 1. Actividades Básicas de la Vida Diaria (AVD) y 2. Actividades Instrumentales de la Vida Diaria (AIVD); para DC 3. Mini Mental State Examination MMS-E; para las características de la marcha, 4. Sistema para Análisis de Marcha GaitRite ©, alphas de 0.730, 0.765, 0.720 y 0.811, respectivamente.
Resultados. La edad promedio de los AM participantes es de 75 años (X = 75 ± 6) y escolaridad de 5 años (X = 5 ± 3). La mayor parte son mujeres (81.9%); que viven sin pareja (74.3%) y reportan alguna enfermedad crónico-degenerativa (65%) como Diabetes, 32.4%; Hipertensión, 61% y Enfermedades Articulares, 42%. La prevalencia de: dependencia severa en ABVD 5.7% y AIVD 21.9 %; DC 24 %; Los AM con mayor edad y menor escolaridad, reportan mayor grado de DC (r= .251; p<.05; r= -.259; p<.05, respectivamente) y dependencia para realizar ABVD (r=.297; p<.05) y AIVD (r=.351; p<.05); Por lo menos, el 30% de AM presentabó dificultades para mantener el equilibrio. Además, el 60% presentó dificultades para sentarse porque tienen problemas al medir la distancia entre su propio cuerpo y la silla, caen en la silla o se apoye en él con movimientos inseguros. 29% presentaba dificultades para elevar su pie derecho completamente.
Discusión y Conclusiones. Los resultados de este estudio confirman lo que la literatura reporta acerca de la prevalencia y asociación de DF, DC y presencia de enfermedades crónicas características del AM como Diabetes e Hipertensión. Es necesario profundizar en el análisis de este estudio incorporando mediciones acerca del tiempo de diagnóstico de la enfermedad crónica, co-morbilidad, síntomas de depresión y diferencias de género, entre otros aspectos. También los factores asociados a la problemática de la marcha. Para el profesional de Enfermería, la continuidad de este fenómeno de estudio, fortalecerá el cuerpo de conocimientos disciplinares y la atención a las complejas necesidades de cuidado a la salud que demanda este segmento de la población. Palabras Clave: Adulto Mayor, Dependencia Funcional, Deterioro Cognitivo, Marcha
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