1,961 research outputs found
In vitro Maturation and Fertilization of Riverine Buffalo Follicular Oocytes in Media Supplemented with Oestrus Buffalo Serum and Hormones
Effects of two maturation media (TCM-199 and Ham's F-12) with and without the addition of oestrus buffalo serum (OBS) and hormones (FSH, LH, E2) on the maturation rate of buffalo follicular oocytes were evaluated. The results revealed a significant (P P 2+ free Tyrode's medium (63.72%) than in TALP (10.9%) and IVF-TL (32.18%). Thus, TCM-199 containing hormones and OBS appeared better for in vitro maturation, whereas modified Ca2+ free tyrode's medium was found to be more suitable for in vitro fertilization of buffalo follicular oocytes
Prevalence of hepatitis B and C viral infections in Pakistan: Findings of a national survey appealing for effective prevention and control measures
A prevalence survey on hepatitis B and C infections was carried out to obtain national estimates and assess epidemiological dynamics and underlying risk factors. Overall prevalence of hepatitis B surface antigen (HBsAg) and anti-hepatitis C virus (HCV) of 2.5% and 4.8%, respectively, reflected a combined infection rate of 7.6% in the general population, consistent with an ongoing high burden of chronic liver disease (CLD). There was significant association of these viral infections with a range of risk factors led by reuse of syringes. These findings validate currently implemented strategies by the national programme for the control of hepatitis viral infections, including universal vaccination of newborns and high-risk groups, support of auto-disable syringes, promotion of infection control and patient safety, public health education, and management of needy CLD patients as a poverty-reduction health intervention
Vestibular schwannomas: Clinical presentation, management and outcome
Objective: To review the demographic trends clinical spectrum, diagnosis, management and outcome of patients with vestibular Schwannoma and to identify areas where improvements are needed.Methods: All patients with vestibular schwannoma admitted to the Aga Khan University Hospital over the past 11 years were reviewed retrospectively.Results: The age range of majority of 22 patients analyzed, was 41-50 years (23%). Hearing loss was the most common presenting symptom (96%). Other clinical features included cranial nerve palsies (59%) and headache (55%). Fifty percent had signs of raised intracranial pressure. Neuroimaging revealed Stage IV b (tumor distorting the brainstem and compressing the 4th ventricle) in 50% cases. Neurosurgical intervention was carried out in 86%; mainly using the retrosigmoid approach. Postoperative complications included facial nerve palsy in 13 (65%) and hydrocephalus in 5 (25%) patients. Hearing determined clinically was preserved in three patients (14%). One patient died during the inpatient stay.Conclusion: Presentation of these patients is late and the outcome is poor
Predictors of mortality in brain abscess
Objective: Brain abscess carries significant morbidity and mortality. Our objective was to elucidate the clinical presentation of brain abscess and to assess predictors of mortality in these patients.Methods: All patients with a brain abscess presenting to the Aga Khan University Hospital, a tertiary care referral center in Karachi, Pakistan, were studied retrospectively. Statistical analysis involved univariate analysis and a logistic regression model.Results: Among the 66 patients analyzed, a distant metastatic focus of infection was the most commonly identified predisposing factor (29%). Otogenic infection was the commonest contiguous source and sinusitis was noticeably absent. Multiple abscesses were frequent (35%). Streptococci were the most common isolates (39%). Lumbar puncture was performed in 44% and steroids administered in 33%. Treatment was surgical in 58%. Most comatose patients were treated conservatively. Overall mortality was 29%. Univariate analysis identified comatose presentation and identification of a distant focus of infection as predictors of mortality. The logistic regression model, however, identified a distant focus of infection as the only independent predictor.Conclusion: Age greater than 30 years, corticosteroid use, multiple abscesses, performance of lumbar puncture and conservative management had no affect on outcome
Dynamics of Tunneling Centers in Metallic Systems
Dynamics of tunneling centers (TC) in metallic systems is studied, using the
technique of bosonization. The interaction of the TC with the conduction
electrons of the metal involves two processes, namely, the screening of the TC
by electrons, and the so-called electron assisted tunneling. The presence of
the latter process leads to a different form of the renormalized tunneling
frequency of the TC, and the tunneling motion is damped with a temperature
dependent relaxation rate. As the temperature is lowered, the relaxation rate
per temperature shows a steep rise as opposed to that in the absence of
electron assisted process. It is expected that this behavior should be observed
at very low temperatures in a careful experiment. The present work thus tries
to go beyond the existing work on the {\it dynamics} of a two-level system in
metals, by treating the electron assisted process.Comment: REVTeX twocolumn format, 5 pages, two PostScript figures available on
request. Preprint # : imsc 94/3
Exploiting Inter- and Intra-Memory Asymmetries for Data Mapping in Hybrid Tiered-Memories
Modern computing systems are embracing hybrid memory comprising of DRAM and
non-volatile memory (NVM) to combine the best properties of both memory
technologies, achieving low latency, high reliability, and high density. A
prominent characteristic of DRAM-NVM hybrid memory is that it has NVM access
latency much higher than DRAM access latency. We call this inter-memory
asymmetry. We observe that parasitic components on a long bitline are a major
source of high latency in both DRAM and NVM, and a significant factor
contributing to high-voltage operations in NVM, which impact their reliability.
We propose an architectural change, where each long bitline in DRAM and NVM is
split into two segments by an isolation transistor. One segment can be accessed
with lower latency and operating voltage than the other. By introducing tiers,
we enable non-uniform accesses within each memory type (which we call
intra-memory asymmetry), leading to performance and reliability trade-offs in
DRAM-NVM hybrid memory. We extend existing NVM-DRAM OS in three ways. First, we
exploit both inter- and intra-memory asymmetries to allocate and migrate memory
pages between the tiers in DRAM and NVM. Second, we improve the OS's page
allocation decisions by predicting the access intensity of a newly-referenced
memory page in a program and placing it to a matching tier during its initial
allocation. This minimizes page migrations during program execution, lowering
the performance overhead. Third, we propose a solution to migrate pages between
the tiers of the same memory without transferring data over the memory channel,
minimizing channel occupancy and improving performance. Our overall approach,
which we call MNEME, to enable and exploit asymmetries in DRAM-NVM hybrid
tiered memory improves both performance and reliability for both single-core
and multi-programmed workloads.Comment: 15 pages, 29 figures, accepted at ACM SIGPLAN International Symposium
on Memory Managemen
Morpho-physiological growth performance and phytoremediation capabilities of selected xerophyte grass species toward Cr and Pb stress
Being sessile organisms, plants cannot escape unwanted changes in the environment. The rapid human population explosion caused significant environmental problems. Heavy metals produced through various sources can cause severe damage to living organisms. The study was planned to evaluate four grass species’ morpho-physiological growth characteristics and phytoremediation capabilities under chromium (Cr) and lead stress (Pb) in the arid climate. Typha angustifolia, Tragus roxburghii, Aeluropus logopoides, and Cenchrus ciliaris grass species were used for the study. One-year-old stubbles from the Cholistan desert were used for the experiment. Cr treatments in the form of K2Cr2O7 were applied at 0, 20, 40, and 80 mg L–1, whereas Pb was applied as PbCl2 at 0, 50, 200, and 500 mg L–1 as control, low, moderate and high-stress, respectively. After 6 weeks of heavy metals treatments, plants were harvested and analyzed for growth performance and phytoremediation capabilities. Results depicted that, regarding morphological attributes, T. angustifolia performed better, followed by C. ciliaris; no clear pattern was observed for T. roxburghii and A. logopoides. The CO2 assimilation rate (Co2d) and water use efficiency (WUE) increased as the heavy metal stress increased in all species under both metals. In contrast, total chlorophyll content was higher under low stress. Other physiological parameters, such as relative humidity (RHd), net photosynthetic rate (A), transpiration rate (E), stomatal conductance (Gs), leaf internal CO2 concentration (Ci) and membrane stability index (MSI) gradually decreased as the Cr, and Pb stress levels increased among all the species. Moreover, Cr and Pb absorption contents of T. angustifolia were higher than the other three species at each stress level. Overall, T. angustifolia thrived against heavy metals stress and showed higher biomass, maximum photosynthetic measurements, WUE and higher metal absorption among all the selected species. Results concluded that although all the selected species behaved fine under stress conditions, T. angustifolia performance was better; thus, it can be used to remediate the soil near industrial estates
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
Adrenomedullin haploinsufficiency predisposes to secondary lymphedema
Secondary lymphedema is a debilitating condition, and genetic factors predisposing to its development remain largely unknown. Adrenomedullin (AM) is peptide encoded, together with proadrenomedullin N-terminal peptide (PAMP), by the Adm gene (adrenomedullin gene). AM and its putative receptor calcitonin receptor-like receptor (CLR) are implicated in angiogenesis and lymphangiogenesis during embryogenesis and wound healing, suggesting their possible involvement in secondary lymphedema. To investigate whether AM deficiency predisposes to secondary lymphedema, we used heterozygous adult mice with Adm gene-knockin stop mutation, which selectively abrogated AM, but preserved PAMP, expression (Adm(AM+/Δ) animals). After hind limb skin incision, Adm messenger RNA expression was upregulated in wounded tissue of both Adm(AM+/+) and Adm(AM+/Δ) mice. However, only Adm(AM+/Δ) animals developed limb swelling and histopathological lymphedematous changes, including epidermal thickening, elevated collagen fiber density, and increased microvessel diameter. Secondary lymphedema was prevented when circulating AM levels in Adm(AM+/Δ) mice were restored by systemic peptide delivery. In human skin, CLR was expressed in tissue components affected by lymphedema, including epidermis, lymphatics, and blood vessels. Our study identified a previously unrecognized role for endogenous AM as a key factor in secondary lymphedema pathogenesis and provided experimental in vivo evidence of an underlying germ-line genetic predisposition to developing this disorder
Ethics-in-practice in fragile contexts: research in education for displaced persons, refugees and asylum seekers
The rising numbers of forcibly displaced peoples on the move globally, and the challenges with providing access to education, reflects the shifting and complex times that we live in. Even though there has been a proliferation in educational research in the context of forced migration, in line with the increasing number of forced migrants, there has not been a commensurate focus on unpicking the increasingly complex ethical conditions within which researchers and participants operate. To examine this issue, the article provides three narrated accounts by researchers in this field and explores the interaction of researcher and researcher-author voice to critically appraise their research experience and identify critical reflections of understanding of ethics-in-practice in fragile contexts. These narratives are framed by the CERD ethical appraisal framework which explores ethical thinking through four ethical lenses – Consequential, Ecological, Relational and Deontological. The article contributes to a deeper understanding of ethics-in-practice as a central dimension in educational research. The implications of this work show how one-size-fits-all approach to ethical appraisal is inappropriate for a socially just educational research. This work also illustrates the importance of attending to relationships and voice of the forcibly displaced, both of which are often lacking in educational research in fragile contexts
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