3,803 research outputs found
Detection of Inositol Polyphosphates by Polyacrylamide Gel Electrophoresis (PAGE) under Apoptotic Conditions in Cultured SW480 Cells
Inositol phosphates are naturally occurring compounds that regulate diverse cellular processes including apoptosis. Apoptosis is a mechanism by which cells undergo natural death to maintain cellular homeostasis. It causes cell death in areas during a state that is harmful to the body. It also regulates cellular development. Previous work has shown that exogenously administered, as well as endogenously manipulated inositol phosphates bring about apoptotic changes. It has been demonstrated that cellular levels of inositol phosphates, particularly higher inositol phosphates such as inositol hexakis-phosphate (IP6) and diphosphoinositol pentakis-phosphate (IP7) levels increase during apoptotic conditions. In this study, we have attempted to separate and identify higher inositol phosphates such as IP6 by polyacrylamide gel electrophoresis (PAGE) and shown that changes in inositol phosphate levels can be detected by this method. Cells were treated with etoposide to induce apoptosis, and apoptotic cells were observed under UV light following ethidium bromide/acridine orange staining. This staining showed that IP3 - IP6 induced apoptosis in SW480 cells with IP6 being the most effective inducing agent. The extracts from apoptotic and control cells were then loaded onto the polyacrylamide gel and run along with standard IP6. Results showed that IP6 could be detected using the PAGE method and that cellular levels of IP6 were increased in SW480 cells, in which apoptosis had been induced by etoposide. Our results demonstrated that this technique could be utilized instead of the laborious radioactive labeling and HPLC separation method to study the changes in cellular levels of inositol phosphates particularly IP6
The Achievable Rate of Interweave Cognitive Radio in the Face of Sensing Errors
Cognitive radio (CR) systems are potentially capable of mitigating the spectrum shortage of contemporary wireless systems. In this paper, we provide a brief overview of CR systems and the important research milestones of their evolution, along with their standardization activities, as a result of their research. This is followed by the detailed analysis of the interweave policy-based CR network (CRN) and by a detailed comparison with the family of underlay-based CRNs. In the interweave-based CRN, sensing of the primary user's (PU) spectrum by the secondary user's (SU) has remained a challenge, because the sensing errors prevent us from fulfilling the significant throughput gains that the concept of CR promises. Since missed detection and false alarm errors in real-time spectrum sensing cannot be avoided, based on a new approach, we quantify the achievable rates of the interweave CR by explicitly incorporating the effect of sensing errors. The link between the PU transmitter and the SU transmitter is assumed to be fast fading. Explicitly, the achievable rate degradation imposed by the sensing errors is analyzed for two spectrum sensing techniques, namely, for energy detection and for magnitude squared coherence-based detection. It is demonstrated that when the channel is sparsely occupied by the PU, the reusing techniques that are capable of simultaneously providing low missed detection and false alarm probabilities cause only a minor degradation to the achievable rates. Furthermore, based on the achievable rates derived for underlay CRNs, we compare the interweave CR and the underlay CR paradigms from the perspective of their resilience against spectrum sensing errors. Interestingly, in many practical regimes, the interweave CR paradigm outperforms the underlay CR paradigm in the presence of sensing errors, especially when the SNR at the SU is below 10 dB and when the SNR at the PU is in the range of 10-40 dB. Furthermore, we also provide rules of thumb that identify regimes, where the interweave CR outperforms the underlay CR
The SAMI Galaxy Survey: the intrinsic shape of kinematically selected galaxies
Using the stellar kinematic maps and ancillary imaging data from the Sydney
AAO Multi Integral field (SAMI) Galaxy Survey, the intrinsic shape of
kinematically-selected samples of galaxies is inferred. We implement an
efficient and optimised algorithm to fit the intrinsic shape of galaxies using
an established method to simultaneously invert the distributions of apparent
ellipticities and kinematic misalignments. The algorithm output compares
favourably with previous studies of the intrinsic shape of galaxies based on
imaging alone and our re-analysis of the ATLAS3D data. Our results indicate
that most galaxies are oblate axisymmetric. We show empirically that the
intrinsic shape of galaxies varies as a function of their rotational support as
measured by the "spin" parameter proxy Lambda_Re. In particular, low spin
systems have a higher occurrence of triaxiality, while high spin systems are
more intrinsically flattened and axisymmetric. The intrinsic shape of galaxies
is linked to their formation and merger histories. Galaxies with high spin
values have intrinsic shapes consistent with dissipational minor mergers, while
the intrinsic shape of low-spin systems is consistent with dissipationless
multi-merger assembly histories. This range in assembly histories inferred from
intrinsic shapes is broadly consistent with expectations from cosmological
simulations.Comment: 15 pages, 11 figures, MNRAS in prin
Distribution of finfish resources along southeast coast of India in relation to certain environmental parameters
This paper embodies the distribution pattern of major finfish resources along the
southeast coast of India as observed during the cruises operated by FORV Sagar
Sampada. A total of 16 cruises (1985-90) operated along latitude 7° 15'- 15°00' N
and longitude 75°50'- 82°3r E hauled a total catch 37.5 tonnes with a catch rate of
537 kg/hr. The catch was constituted mainly by threadfin breams (43%), perches
(14%), barracudas (9.72%), carangids (8.56%) and elasmobranchs (4.81%). Seasonally
higher catch rates were obtained during July- September period. Depth range of
60 - 80 m had denser population of finfish resources. Water temperature and salinity
appeared to influence the distribution of major finfishes more than dissolved oxygen.
Groups such as threadfin breams were found preferring cooler waters of Wadge Bank
area, while barracudas appear to occupy warmer waters of Gulf of Mannar
Occurrence of ribbonfish in the Indian EEZ
The survey conducted by FORV Sagar Sampada during 1985-91 (90 cruises)
revealed the occurrence of ribbonfish in 56 stations out of 904 stations where fishing
was conducted. It was reported from 41 stations along the west coast and 14 stations
along the east coast. About 14 tonne of ribbonfish was caught in these operations
which formed 4.8% of the total fish catch. West coast was more productive and
contributed 93.6% of the catch, while the east coast only 6.4%. It abundantly
occurred in the southwest, centralwest, northwest and northeast coasts. Depth-wise
study revealed that major portion of the catch was obtained from within the 100 m
depth zone. The dominant species reported was Trichiurus leptur
The mysterious optical afterglow spectrum of GRB140506A at z=0.889
Context. Gamma-ray burst (GRBs) afterglows probe sightlines to star-forming
regions in distant star-forming galaxies. Here we present a study of the
peculiar afterglow spectrum of the z = 0.889 Swift GRB 140506A. Aims. Our aim
is to understand the origin of the very unusual properties of the absorption
along the line-of-sight. Methods. We analyse spectroscopic observations
obtained with the X-shooter spectrograph mounted on the ESO/VLT at two epochs
8.8 h and 33 h after the burst as well as imaging from the GROND instrument. We
also present imaging and spectroscopy of the host galaxy obtained with the
Magellan telescope. Results. The underlying afterglow appears to be a typical
afterglow of a long-duration GRB. However, the material along the line-of-
sight has imprinted very unusual features on the spectrum. Firstly, there is a
very broad and strong flux drop below 8000 AA (4000 AA in the rest frame),
which seems to be variable between the two spectroscopic epochs. We can
reproduce the flux-drops both as a giant 2175 AA extinction bump and as an
effect of multiple scattering on dust grains in a dense environment. Secondly,
we detect absorption lines from excited H i and He i. We also detect molecular
absorption from CH+ . Conclusions. We interpret the unusual properties of these
spectra as reflecting the presence of three distinct regions along the
line-of-sight: the excited He i absorption originates from an H ii-region,
whereas the Balmer absorption must originate from an associated
photodissociation region. The strong metal line and molecular absorption and
the dust extinction must originate from a third, cooler region along the
line-of-sight. The presence of (at least) three separate regions is reflected
in the fact that the different absorption components have different velocities
relative to the systemic redshift of the host galaxy.Comment: 8 pages, 4 figures. Accepted for publications in A&
Association Between Residential Greenness and Cardiovascular Disease Risk
Background Exposure to green vegetation has been linked to positive health, but the pathophysiological processes affected by exposure to vegetation remain unclear. To study the relationship between greenness and cardiovascular disease, we examined the association between residential greenness and biomarkers of cardiovascular injury and disease risk in susceptible individuals. Methods and Results In this cross-sectional study of 408 individuals recruited from a preventive cardiology clinic, we measured biomarkers of cardiovascular injury and risk in participant blood and urine. We estimated greenness from satellite-derived normalized difference vegetation index ( NDVI ) in zones with radii of 250 m and 1 km surrounding the participants' residences. We used generalized estimating equations to examine associations between greenness and cardiovascular disease biomarkers. We adjusted for residential clustering, demographic, clinical, and environmental variables. In fully adjusted models, contemporaneous NDVI within 250 m of participant residence was inversely associated with urinary levels of epinephrine (-6.9%; 95% confidence interval, -11.5, -2.0/0.1 NDVI ) and F2-isoprostane (-9.0%; 95% confidence interval, -15.1, -2.5/0.1 NDVI ). We found stronger associations between NDVI and urinary epinephrine in women, those not on β-blockers, and those who had not previously experienced a myocardial infarction. Of the 15 subtypes of circulating angiogenic cells examined, 11 were inversely associated (8.0-15.6% decrease/0.1 NDVI ), whereas 2 were positively associated (37.6-45.8% increase/0.1 NDVI ) with contemporaneous NDVI . Conclusions Independent of age, sex, race, smoking status, neighborhood deprivation, statin use, and roadway exposure, residential greenness is associated with lower levels of sympathetic activation, reduced oxidative stress, and higher angiogenic capacity
Fairness in Algorithmic Decision Making: An Excursion Through the Lens of Causality
As virtually all aspects of our lives are increasingly impacted by
algorithmic decision making systems, it is incumbent upon us as a society to
ensure such systems do not become instruments of unfair discrimination on the
basis of gender, race, ethnicity, religion, etc. We consider the problem of
determining whether the decisions made by such systems are discriminatory,
through the lens of causal models. We introduce two definitions of group
fairness grounded in causality: fair on average causal effect (FACE), and fair
on average causal effect on the treated (FACT). We use the Rubin-Neyman
potential outcomes framework for the analysis of cause-effect relationships to
robustly estimate FACE and FACT. We demonstrate the effectiveness of our
proposed approach on synthetic data. Our analyses of two real-world data sets,
the Adult income data set from the UCI repository (with gender as the protected
attribute), and the NYC Stop and Frisk data set (with race as the protected
attribute), show that the evidence of discrimination obtained by FACE and FACT,
or lack thereof, is often in agreement with the findings from other studies. We
further show that FACT, being somewhat more nuanced compared to FACE, can yield
findings of discrimination that differ from those obtained using FACE.Comment: 7 pages, 2 figures, 2 tables.To appear in Proceedings of the
International Conference on World Wide Web (WWW), 201
An Introduction to Gas Accretion onto Galaxies
Evidence for gas accretion onto galaxies can be found throughout the
universe. In this chapter, I summarize the direct and indirect signatures of
this process and discuss the primary sources. The evidence for gas accretion
includes the star formation rates and metallicities of galaxies, the evolution
of the cold gas content of the universe with time, numerous indirect indicators
for individual galaxies, and a few direct detections of inflow. The primary
sources of gas accretion are the intergalactic medium, satellite gas and
feedback material. There is support for each of these sources from observations
and simulations, but the methods with which the fuel ultimately settles in to
form stars remain murky.Comment: 14 pages, 5 figures, Invited review to appear in Gas Accretion onto
Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e,
to be published by Springe
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