2,246 research outputs found
Interface driven magnetoelectric effects in granular CrO2
Antiferromagnetic and magnetoelectric Cr2O3-surfaces strongly affect the
electronic properties in half metallic CrO2. We show the presence of a Cr2O3
surface layer on CrO3 grains by high-resolution transmission electron
microscopy. The effect of these surface layers is demonstrated by measurements
of the temperature variation of the magnetoelectric susceptibility. A major
observation is a sign change at about 100 K followed by a monotonic rise as a
function of temperature. These electric field induced moments in CrO3 are
correlated with the magnetoelectric susceptibility of pure Cr2O3. This study
indicates that it is important to take into account the magnetoelectric
character of thin surface layers of Cr2O3 in granular CrO2 for better
understanding the transport mechanism in this system. The observation of a
finite magnetoelectric susceptibility near room temperature may find utility in
device applications.Comment: Figure 1 with strongly reduced resolutio
How varying CD4 criteria for treatment initiation was associated with mortality of HIV-patients? A retrospective analysis of electronic health records from Andhra Pradesh, India
Background HIV treatment and care services were scaled up in 2007 in India with objective to increase HIV-care coverage. CD4 count based criteria was mainly used for treatment initiation with increasing threshold in later years. Therefore, this paper aimed to evaluate the survival by varying CD4 criteria for antiretroviral treatment (ART) initiation among of HIV-positive patients, and independent factors associated with the mortality. Methods This retrospective cohort study included 127 949 HIV-positive patients aged ≥15 years, who initiated ART between 2007 and 2013 in Andhra Pradesh state, India. The patient’s demographic and clinical characteristics were extracted from the patient’s health records from electronic Computerized Management Information System Software (CMIS). Incidence of mortality/100 person-years was calculated for CD4 and treatment initiation categories. Kaplan-Meier and multivariable Cox-regression analyses were used to explore the association. Results Median CD4 count was 172 (inter-quartile range (IQR) = 102-240) at the time of treatment initiation, and 19.3% of them had ≤ 100 CD4 count. Incidence of mortality for the period 2007-08 (CD4 ≤ 200 cells/mm3) was 8.5/100 person-years compared to 6.4/100 person-years at risk for the period 2012 onwards (CD4 ≤ 350 cells/mm3). Earlier thresholds for treatment initiation showed higher risk of mortality (2007-08 (CD4 ≤ 200 cells/mm3), adjusted hazard ratio (HR): 1.86, 95% confidence interval (CI): 1.68-2.07; 2009-11 (CD4 ≤ 250 cells/mm3), HR = 1.67, 95% CI = 1.51-1.85) compared to 2012 onwards (CD4 ≤ 350 cells/mm3) criteria for treatment initiation. Conclusions Increasing CD4 threshold for treatment initiation over time was independently associated with lower risk of mortality. More efforts are required to detect and treat early, monitoring of follow-ups, promote health education to improve ART adherence, and provide supportive environment that encourages HIV-infected patients to disclose their HIV status in confidence
Epoxy based hybrid nanocomposites: Fracture mechanisms, tensile properties and electrical properties
Development of a heating reactor for a continuous flow-through application in urea measurement
In most biochemical analyses, a flow-through heating arrangement is needed to reduce the reaction time or maintain a constant temperature. A rectangular reactor is described that is constructed of aluminium, is hollow inside and is filled with silicone oil. The glass coil through which the solution flows is immersed in the silicone oil. The heater, a Peltier-effect heat pump, on one side and the temperature sensor on the other side of the reactor body are embedded for heating and temperature control. The brief performance evaluation of the reactor is discussed by measuring the absorbance of urea concentration at different temperatures
Selective substitution in orbital domains of a low doped manganite : an investigation from Griffiths phenomenon and modification of glassy features
An effort is made to study the contrast in magnetic behavior resulting from
minimal disorder introduced by substitution of 2.5% Ga or Al in Mn-site of
LaSrMnO. It is considered that Ga or Al selectively
creates disorder within the orbital domains or on its walls, causing
enhancement of Griffiths phase (GP) singularity for the former and
disappearance of it in the later case. It is shown that Ga replaces Mn
which is considered to be concentrated within the domains, whereas Al replaces
Mn which is segregated on the hole-rich walls, without causing any
significant effect on structure or ferromagnetic transition temperatures. Thus,
it is presumed that the effect of disorder created by Ga extend across the bulk
of the domain having correlation over similar length-scale resulting in
enhancement of GP phenomenon. On the contrary, effect of disorder created by Al
remains restricted to the walls resulting in the modification of the dynamics
arising from the domain walls and suppresses the GP. Moreover contrasting
features are observed in the low temperature region of the compounds; a
re-entrant spin glass like behavior is observed in the Ga doped sample, while
the observed characteristics for the Al doped sample is ascribed only to
modified domain wall dynamics with the absence of any glassy phase. Distinctive
features in third order susceptibility measurements reveals that the magnetic
ground state of the entire series comprises of orbital domain states. These
observations bring out the role of the nature of disorder on GP phenomenon and
also reconfirms the character of self-organization in low-doped manganites
Formation of finite antiferromagnetic clusters and the effect of electronic phase separation in Pr{_0.5}Ca{_0.5}Mn{_0.975}Al{_0.025}O{_3}
We report the first experimental evidence of a magnetic phase arising due to
the thermal blocking of antiferromagnetic clusters in the weakened charge and
orbital ordered system Pr{_0.5}Ca{_0.5}Mn{_0.975}Al{_0.025}O{_3}. The third
order susceptibility (\chi_3) is used to differentiate this transition from a
spin or cluster glass like freezing mechanism. These clusters are found to be
mesoscopic and robust to electronic phase separation which only enriches the
antiphase domain walls with holes at the cost of the bulk, without changing the
size of these clusters. This implies that Al substitution provides sufficient
disorder to quench the length scales of the striped phases.Comment: 4 Post Script Figure
Toward a More Nuanced Interpretation of Statistical Significance in Biomedical Research
Editorial
Statistical significance is the bedrock of evidence-based medicine, crucial for decision-making and framing biomedical science policies. The emergence of complex data in many disciplines, resulting from the analysis of large datasets, has amplified the popularity of p-values. Its simplicity allows investigators to conclude and disseminate their research findings in a manner understood by most. Thus, obtaining a p-value that indicates “statistical significance” against the null hypothesis is often required for publishing in medical journals. However, it creates challenges due to nonreproducibility, misuse and overinterpretation, which lead to serious methodological errors. This article aims to draw biomedical researchers' attention toward the appropriate use of p-values in clinical decision-making
Identifying Prognostic Groups Using Machine Learning Tools in Patients Undergoing Chemoradiation for Inoperable Locally Advanced Nonsmall Cell Lung Carcinoma
Introduction
Unresectable stage III nonsmall cell lung cancer (NSCLC) continues to have dismal 5-year overall survival (OS) rate. However, a subset of the patients treated with chemoradiation show significantly better outcome. Prediction of treatment outcome can be improved by utilizing machine learning tools, such as cluster analysis (CA), and is capable of identifying complex interactions among many variables. We have utilized CA to identify a cluster with good prognosis within stage III NSCLC.
Materials and Methods
Retrospective analysis of treatment outcomes was done for 92 patients who underwent chemoradiation for inoperable locally advanced NSCLC from 2012 to 2018. Using various patient- and treatment-related variables, an exploratory factor analysis was performed to extract factors with eigenvalue > 1. An appropriate number of homogeneous groups were identified using agglomerative hierarchical cluster analysis. Further K-mean cluster analysis was applied to classify each patient into their homogeneous clusters. The newly formed cluster variable was used as an independent variable to estimate survival over time using Kaplan–Meier method.
Results
With a median follow-up of 18 months, median OS was 14 months. Using CA, three prognostic clusters were obtained. Cluster 2 with 36 patients had a median OS of 36 months, whereas Cluster 1 with 34 patients had a median OS of 20 months (p = 0.004).
Conclusion
A cluster could thus be identified with a relatively good prognosis within stage III NSCLC. Using CA, we have attempted to create a model which may provide more specific prognostic information in addition to that provided by tumor node metastasis-based models
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