3,688 research outputs found
Sound radiation from a high speed axial flow fan due to the inlet turbulence quadrupole interaction
A formula is obtained for the total acoustic power spectra radiated out the front of the fan as a function of frequency. The formula involves the design parameters of the fan as well as the statistical properties of the incident turbulence. Numerical results are calculated for values of the parameters in the range of interest for quiet fans tested at the Lewis Research Center. As in the dipole analysis, when the turbulence correlation lengths become equal to the interblade spacing, the predicted spectra exhibit peaks around the blade passing frequency and its harmonics. There has recently been considerable conjecture about whether the stretching of turbulent eddies as they enter a stationary fan could result in the inlet turbulence being the dominant source of pure tones from nontranslating fans. The results of the current analysis show that, unless the turbulent eddies become quite elongated, this noise source contributes predominantly to the broadband spectrum
On the Structure of Equilibria in Basic Network Formation
We study network connection games where the nodes of a network perform edge
swaps in order to improve their communication costs. For the model proposed by
Alon et al. (2010), in which the selfish cost of a node is the sum of all
shortest path distances to the other nodes, we use the probabilistic method to
provide a new, structural characterization of equilibrium graphs. We show how
to use this characterization in order to prove upper bounds on the diameter of
equilibrium graphs in terms of the size of the largest -vicinity (defined as
the the set of vertices within distance from a vertex), for any
and in terms of the number of edges, thus settling positively a conjecture of
Alon et al. in the cases of graphs of large -vicinity size (including graphs
of large maximum degree) and of graphs which are dense enough.
Next, we present a new swap-based network creation game, in which selfish
costs depend on the immediate neighborhood of each node; in particular, the
profit of a node is defined as the sum of the degrees of its neighbors. We
prove that, in contrast to the previous model, this network creation game
admits an exact potential, and also that any equilibrium graph contains an
induced star. The existence of the potential function is exploited in order to
show that an equilibrium can be reached in expected polynomial time even in the
case where nodes can only acquire limited knowledge concerning non-neighboring
nodes.Comment: 11 pages, 4 figure
Inhibitory effect on ovarian cancer ALDH+ stem-like cells by Disulfiram and Copper treatment through ALDH and ROS modulation
BACKGROUND:
Disulfiram (DSF) is a drug used for treatment of alcoholism that has also displayed promising anti-cancer activity. It unfolds its effects by inhibiting the enzyme activity of aldehyde dehydrogenase (ALDH) isoforms.
METHODS:
MTT assay, spheroid formation, clonogenicity assay, qRT-PCR, and ALDH enzyme activity analysis were performed using ovarian cancer cell lines IGROV1, SKOV3 and SKOV3IP1. Cell cycle analyses and measurement of intracellular reactive oxygen species (ROS) were carried out by flow cytometry. ALDH+ and ALDH- cells were isolated by FACS sorting.
RESULTS:
ALDH activity was inhibited in ovarian cancer stem cells (the proportion of ALDH+ cells was reduced from 21.7% to 0.391%, 8.4% to 0%, 6.88% to 0.05% in cell lines IGROV1, SKOV3, and SKOV3IP1, respectively). DSF with or without the cofactor copper (Cu2+) exhibited cytotoxicity dose- and time-dependent and enhanced cisplatin-induced apoptosis. DSF + Cu2+ increased intracellular ROS levels triggering apoptosis of ovarian cancer stem cells (CSC). Significantly more colony and spheroid formation was observed in ALDH+ compared with ALDH- cells (P < 0.01). Moreover, ALDH+ cells were more resistant to cisplatin treatment compared with ALDH-cells (P < 0.05) and also exhibited a lower basal level of ROS. However, no significant difference in ROS accumulation nor in cellular viability was observed in ALDH + cells in comparison to ALDH- cells after pre-treatment with DSF (0.08 μM).
CONCLUSION:
Our findings provide evidence that DSF might be employed as a novel adjuvant chemotherapeutic agent in combination with cisplatin for treatment of ovarian cancer
The Electronic Correlation Strength of Pu
An electronic quantity, the correlation strength, is defined as a necessary
step for understanding the properties and trends in strongly correlated
electronic materials. As a test case, this is applied to the different phases
of elemental Pu. Within the GW approximation we have surprisingly found a
"universal" scaling relationship, where the f-electron bandwidth reduction due
to correlation effects is shown to depend only on the local density
approximation bandwidth and is otherwise independent of crystal structure and
lattice constant.Comment: 7 pages, 4 figures, This version of the paper has been revised to add
additional background informatio
Throughput Maximization in Multiprocessor Speed-Scaling
We are given a set of jobs that have to be executed on a set of
speed-scalable machines that can vary their speeds dynamically using the energy
model introduced in [Yao et al., FOCS'95]. Every job is characterized by
its release date , its deadline , its processing volume if
is executed on machine and its weight . We are also given a budget
of energy and our objective is to maximize the weighted throughput, i.e.
the total weight of jobs that are completed between their respective release
dates and deadlines. We propose a polynomial-time approximation algorithm where
the preemption of the jobs is allowed but not their migration. Our algorithm
uses a primal-dual approach on a linearized version of a convex program with
linear constraints. Furthermore, we present two optimal algorithms for the
non-preemptive case where the number of machines is bounded by a fixed
constant. More specifically, we consider: {\em (a)} the case of identical
processing volumes, i.e. for every and , for which we
present a polynomial-time algorithm for the unweighted version, which becomes a
pseudopolynomial-time algorithm for the weighted throughput version, and {\em
(b)} the case of agreeable instances, i.e. for which if and only
if , for which we present a pseudopolynomial-time algorithm. Both
algorithms are based on a discretization of the problem and the use of dynamic
programming
A Simple Modeling Framework For Prediction In The Human Glucose-Insulin System
In this paper, we build a new, simple, and interpretable mathematical model
to describe the human glucose-insulin system. Our ultimate goal is the robust
control of the blood glucose (BG) level of individuals to a desired healthy
range, by means of adjusting the amount of nutrition and/or external insulin
appropriately. By constructing a simple yet flexible model class, with
interpretable parameters, this general model can be specialized to work in
different settings, such as type 2 diabetes mellitus (T2DM) and intensive care
unit (ICU); different choices of appropriate model functions describing uptake
of nutrition and removal of glucose differentiate between the models. In both
cases, the available data is sparse and collected in clinical settings, major
factors that have constrained our model choice to the simple form adopted.
The model has the form of a linear stochastic differential equation (SDE) to
describe the evolution of the BG level. The model includes a term quantifying
glucose removal from the bloodstream through the regulation system of the human
body, and another two terms representing the effect of nutrition and externally
delivered insulin. The parameters entering the equation must be learned in a
patient-specific fashion, leading to personalized models. We present numerical
results on patient-specific parameter estimation and future BG level
forecasting in T2DM and ICU settings. The resulting model leads to the
prediction of the BG level as an expected value accompanied by a band around
this value which accounts for uncertainties in the prediction. Such
predictions, then, have the potential for use as part of control systems which
are robust to model imperfections and noisy data. Finally, a comparison of the
predictive capability of the model with two different models specifically built
for T2DM and ICU contexts is also performed.Comment: 47 pages, 9 figures, 7 table
A Meta-Analysis
Background p16INK4a is a tumor suppressor protein which is induced in cells
upon the interaction of high-risk HPV E7 with the retinoblastoma protein by a
positive feedback loop, but cannot exert its suppressing effect. Previous
reports suggested that p16INK4a immunostaining allows precise identification
of even small CIN or cervical cancer lesions in biopsies. The prognostic value
of overexpressed p16INK4a in cervical cancer has been evaluated for several
years while the results remain controversial. We performed a systematic review
and meta-analysis of studies assessing the clinical and prognostic
significance of overexpression of p16INK4a in cervical cancer. Methods
Identification and review of publications assessing clinical or prognostic
significance of p16INK4a overexpression in cervical cancer until March 1,
2014. A meta-analysis was performed to clarify the association between
p16INK4a overexpression and clinical outcomes. Results A total of 15
publications met the criteria and comprised 1633 cases. Analysis of these data
showed that p16INK4a overexpression was not significantly associated with
tumor TNM staging (I+II vs. III+IV) (OR = 0.75, 95% confidence interval [CI]:
0.35–1.63, P = 0.47), the tumor grade (G1+ G2 vs. G3) (OR = 0.78, 95% CI:
0.39–1.57, P = 0.49), the tumor size (<4 vs. ≥4 cm) (OR = 1.10, 95% CI:
0.45–2.69, P = 0.83), or vascular invasion (OR = 1.20, 95% CI: 0.69–2.08, P =
0.52). However, in the identified studies, overexpression of p16INK4a was
highly correlated with no lymph node metastasis (OR = 0.51, 95% CI: 0.28–0.95,
P = 0.04), increased overall survival (relative risk [RR]: 0.42, 95% CI:
0.24–0.72, P = 0.002) and increased disease free survival (RR: 0.60, 95% CI:
0.44–0.82, P = 0.001)
Network Creation Games: Think Global - Act Local
We investigate a non-cooperative game-theoretic model for the formation of
communication networks by selfish agents. Each agent aims for a central
position at minimum cost for creating edges. In particular, the general model
(Fabrikant et al., PODC'03) became popular for studying the structure of the
Internet or social networks. Despite its significance, locality in this game
was first studied only recently (Bil\`o et al., SPAA'14), where a worst case
locality model was presented, which came with a high efficiency loss in terms
of quality of equilibria. Our main contribution is a new and more optimistic
view on locality: agents are limited in their knowledge and actions to their
local view ranges, but can probe different strategies and finally choose the
best. We study the influence of our locality notion on the hardness of
computing best responses, convergence to equilibria, and quality of equilibria.
Moreover, we compare the strength of local versus non-local strategy-changes.
Our results address the gap between the original model and the worst case
locality variant. On the bright side, our efficiency results are in line with
observations from the original model, yet we have a non-constant lower bound on
the price of anarchy.Comment: An extended abstract of this paper has been accepted for publication
in the proceedings of the 40th International Conference on Mathematical
Foundations on Computer Scienc
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