1,048 research outputs found
Identification of a component of Drosophila polar granules
Information necessary for the formation of pole cells, precursors of the germ line, is provided maternally and localized to the posterior pole of the Drosophila egg. The maternal origin and posterior localization of polar granules suggest that they may be associated with pole cell determinants. We have generated an antibody (Mab46F11) against polar granules. In oocytes and early embryos, the Mab46F11 antigen is sharply localized to the posterior embryonic pole. In pole cells, it becomes associated with nuclear bodies within, and nuage around, the nucleus. Immunoreactivity remains associated with cells of the germ line throughout the life cycle of both males and females. This antibody recognizes a 72-74 X 10^(3) Mr protein and is useful both as a pole lineage marker and in biochemical studies of polar granules
Sources Of Income Inequality Among the Elderly
Sources of inequality among American households with a retired elderly head were examined by decomposition of Gini coefficients. Inequality of investment and labor income contributed most to overall income inequality. Income inequality of three types of households couples with one retiree, retired couples, and retired singles were studied in terms of sources of income inequality. Inequality of investment income contributed most to income inequality for retired singles and for retired couples
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R&D on an Ultra-Thin Composite Membrane for High-Temperature Operation in PEMFC. Final Report
FuelCell Energy developed a novel high-temperature proton exchange membrane for PEM fuel cells for building applications. The laboratory PEM fuel cell successfully operated at 100-400{supdegree}C and low relative humidity to improve CO tolerance, mitigate water and thermal management challenges, and reduce membrane cost. The developed high-temperature membrane has successfully completed 500h 120C endurance testing
An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport due to Reversed Magnetic Shear
The first nonlinear gyrokinetic simulations of electron internal transport
barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed
magnetic shear can suppress thermal transport by increasing the nonlinear
critical gradient for electron-temperature-gradient-driven turbulence to three
times its linear critical value. An interesting feature of this turbulence is
nonlinearly driven off-midplane radial streamers. This work reinforces the
experimental observation that magnetic shear is likely an effective way of
triggering and sustaining e-ITBs in magnetic fusion devices.Comment: 4 pages, 5 figure
An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport due to Reversed Magnetic Shear
The first nonlinear gyrokinetic simulations of electron internal transport
barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed
magnetic shear can suppress thermal transport by increasing the nonlinear
critical gradient for electron-temperature-gradient-driven turbulence to three
times its linear critical value. An interesting feature of this turbulence is
nonlinearly driven off-midplane radial streamers. This work reinforces the
experimental observation that magnetic shear is likely an effective way of
triggering and sustaining e-ITBs in magnetic fusion devices.Comment: 4 pages, 5 figure
Human parathyroid hormone fragment stimulates the de novo synthesis of prostaglandin endoperoxide synthase in chick calvaria
The human parathyroid hormone N-terminal fragment [hPTH-(1–34)] increases the conversion of exogenous unsaturated fatty acids to prostaglandins (PGs) in calvarial homogenates. Enzyme activities were completely blocked by indomethacin (5 × 10−7 M), a PG synthase inhibitor, and actinomycin D (5 μM), an inhibitor of transcription, by binding to DNA. In addition, a potent inhibitor of protein synthesis, cycloheximide (10 μM), totally inhibited the stimulating effect of hPTH-(1–34) on prostaglandin endoperoxide synthase (PG synthase, EC 1.14.99.1). The stimulatory effect of hPTH-(1–34) on PG synthase was also reduced by the addition of stannous chloride. However, epidermal growth factor (EGF), platelet-derived activating factor (PDGF), and ionophore A23187 did not show the same stimulating effect as hPTH-(1–34) on PG synthase in calvaria. The results further demonstrated that PG synthase is a membrane-bound enzyme in chick calvaria. In this communication, evidence is presented that hPTH-(1–34) stimulates the de novo synthesis of PG synthase as demonstrated by the increased activity in calvarial homogenates and microsomes
Federated Learning for Sparse Principal Component Analysis
In the rapidly evolving realm of machine learning, algorithm effectiveness
often faces limitations due to data quality and availability. Traditional
approaches grapple with data sharing due to legal and privacy concerns. The
federated learning framework addresses this challenge. Federated learning is a
decentralized approach where model training occurs on client sides, preserving
privacy by keeping data localized. Instead of sending raw data to a central
server, only model updates are exchanged, enhancing data security. We apply
this framework to Sparse Principal Component Analysis (SPCA) in this work. SPCA
aims to attain sparse component loadings while maximizing data variance for
improved interpretability. Beside the L1 norm regularization term in
conventional SPCA, we add a smoothing function to facilitate gradient-based
optimization methods. Moreover, in order to improve computational efficiency,
we introduce a least squares approximation to original SPCA. This enables
analytic solutions on the optimization processes, leading to substantial
computational improvements. Within the federated framework, we formulate SPCA
as a consensus optimization problem, which can be solved using the Alternating
Direction Method of Multipliers (ADMM). Our extensive experiments involve both
IID and non-IID random features across various data owners. Results on
synthetic and public datasets affirm the efficacy of our federated SPCA
approach.Comment: 11 pages, 7 figures, 1 table. Accepted by IEEE BigData 2023,
Sorrento, Ital
Identification of E2/E3 Ubiquitinating Enzymes and Caspase Activity Regulating Drosophila Sensory Neuron Dendrite Pruning
SummaryUbiquitin-proteasome system (UPS) is a multistep protein degradation machinery implicated in many diseases. In the nervous system, UPS regulates remodeling and degradation of neuronal processes and is linked to Wallerian axonal degeneration, though the ubiquitin ligases that confer substrate specificity remain unknown. Having shown previously that class IV dendritic arborization (C4da) sensory neurons in Drosophila undergo UPS-mediated dendritic pruning during metamorphosis, we conducted an E2/E3 ubiquitinating enzyme mutant screen, revealing that mutation in ubcD1, an E2 ubiquitin-conjugating enzyme, resulted in retention of C4da neuron dendrites during metamorphosis. Further, we found that UPS activation likely leads to UbcD1-mediated degradation of DIAP1, a caspase-antagonizing E3 ligase. This allows for local activation of the Dronc caspase, thereby preserving C4da neurons while severing their dendrites. Thus, in addition to uncovering E2/E3 ubiquitinating enzymes for dendrite pruning, this study provides a mechanistic link between UPS and the apoptotic machinery in regulating neuronal process remodeling
Performance evaluation of distributed systems with unbalanced flows : an analysis of the INFOPLEX data storage hierarchy
Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY.Bibliography: leaves 165-171.by Yng-Yuh Richard Wang.Ph.D
Excitonic BCS-BEC crossover at finite temperature: Effects of repulsion and electron-hole mass difference
The BCS to Bose-Einstein condensation (BEC) crossover of electron-hole (e-h)
pairs in optically excited semiconductors is studied using the two-band Hubbard
model with both repulsive and attractive interactions. Applying the
self-consistent t-matrix approximation combined with a local approximation, we
examine the properties of a normal phase and an excitonic instability. The
transition temperature from the normal phase to an e-h pair condensed one is
studied to clarify the crossover from an e-h BCS-like state to an excitonic
Bose-Einstein condensation, which takes place on increasing the e-h attraction
strength. To investigate effects of the repulsive interaction and the e-h mass
difference, we calculate the transition temperature for various parameters of
the interaction strengths, the e-h particle density, and the mass difference.
While the transition temperature in the e-h BCS regime is sufficiently
suppressed by the repulsive interaction, that of the excitonic BEC is largely
insensitive to it. We also show quantitatively that in the whole regime the
mass difference leads to large suppression of the transition temperature.Comment: 8 pages, 7 figures, to be published in Phys. Rev.
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