2,783 research outputs found
Efficiency analysis of load balancing games with and without activation costs
In this paper, we study two models of resource allocation games: the classical load-balancing game and its new variant involving resource activation costs. The resources we consider are identical and the social costs of the games are utilitarian, which are the average of all individual players' costs.
Using the social costs we assess the quality of pure Nash equilibria in terms of the price of anarchy (PoA) and the price of stability (PoS). For each game problem, we identify suitable problem parameters and provide a parametric bound on the PoA and the PoS. In the case of the load-balancing game, the parametric bounds we provide are sharp and asymptotically tight
Resource allocation games of various social objectives
In this paper, we study resource allocation games of two different cost components for individual game players and various social costs. The total cost of each individual player consists of the congestion cost, which is the same for all players sharing the same resource, and resource activation cost, which is proportional to the individual usage of the resource. The social costs we consider are, respectively, the total of costs of all players and the maximum congestion cost plus total resource activation cost.
Using the social costs we assess the quality of Nash equilibria in terms of the price of anarchy (PoA) and the price of stability (PoS). For each problem, we identify one or two problem parameters and provide parametric bounds on the PoA and PoS. We show that they are unbounded in general if the parameter involved are not restricted
Effects of charging and electric field on the properties of silicene and germanene
Using first-principles Density Functional Theory calculations, we showed that
electronic and magnetic properties of bare and Ti adatom adsorbed single-layer
silicene and germanene, which are charged or exerted by a perpendicular
electric field are modified to attain new functionalities. In particular, when
exerted by a perpendicular electric field, the symmetry between the planes of
buckled atoms is broken to open a gap at the Dirac points. The occupation of
3d-orbitals of adsorbed Ti atom changes with charging or applied electric field
to induce significant changes of magnetic moment. We predict that neutral
silicene uniformly covered by Ti atoms becomes a half-metal at a specific value
of coverage and hence allows the transport of electrons in one spin direction,
but blocks the opposite direction. These calculated properties, however exhibit
a dependence on the size of the vacuum spacing between periodically repeating
silicene and germanene layers, if they are treated using plane wave basis set
within periodic boundary condition. We clarified the cause of this spurious
dependence and show that it can be eliminated by the use of local orbital basis
set.Comment: Accepted for Journal of Physics: Condensed Matte
Coupled surface plasmon structures and applications
Ankara : The Graduate Program of Materials Science and Nanotechnology and the Institute of Engineering and Sciences of Bilkent University, 2009.Thesis (Master's) -- Bilkent University, 2009.Includes bibliographical references leaves 55-58.Surface plasmons have attracted great interest during past decades due to their
unique physical properties. In this thesis, we study grating-coupled surface plasmons
for sensing and filtering applications. We first present simple physical
and chemical procedures that allow tuning and modification of the topography
of gratings present in optical storage discs into geometries optimal for grating
coupled plasmon resonance excitation. After proper metal coating, the tuned
surfaces exhibit sharp plasmon resonances that can be excited at wavelengths
ranging from 260 nm to over 2.7 µm with relatively high quality factors. As
an immediate exemplary application, use of such optimized gratings in aqueous
medium for refractive index measurement is demonstrated.
We also report another plasmonic component based on a pair of surfaces displaying
grating coupled plasmon enhanced transmission. We observe high quality
factor transmission peaks as high as 100 through our plasmonic filter based on
gratings obtained directly from optical storage disks. Wavelength and polarization
dependent transmission is also demonstrated in the visible and infrared
portions of the spectrum. The resonance wavelength of this filter can be tuned
by simply changing the angle of incidence. Numerical calculations agree well with measurements. Our work can open up directions toward disposable optical
components such as filters and polarizers.
Morever, we investigate plasmonic force between two coupled metallic layers.
We observe the mode splitting due to coupling between plasmonic surfaces by
using finite difference time domain simulations.Gürel, KemalM.S
Recommended from our members
Not-so-magic Bullets: Searching for Better Policies to Govern Drug Discovery
In his upcoming book, Strange Pill: Evidence, Values, and Medical Nihilism, philosopher of Jacob Stegenga charts a history of the term “magic bullet”: a drug that is both specific and effective, curing the patient without side effects. Stegenga argues that the early 20th century was a “golden age” for magic bullets, with the discovery of drugs like penicillin and insulin, and that late 20th/early 21st century medicine has not been able to deliver drugs that are nearly as effective. I propose, by interviewing Stegenga, to outline why recently discovered drugs tend to have tiny effect sizes and bad side effects (and therefore a poor cost/benefit ratio.) I will then outline proposals for how the modern medical research agenda can be restructured so that its products more closely resemble “magic bullets,” an outcome that would save the NHS money and improve the patient experience
Recommended from our members
Intratumoral B and T cell receptors: reconstruction and analysis
When cells divide, mistakes happen. However, an intricate surveillance system has evolved to detect and eliminate anomalous cells before they become detrimental to the host organism. In cancer, abnormal cells manage to escape the immune system and grow uncontrollably. In this sense, cancer can be considered as an oversight of the immune system, as immune escape is a defining feature of clinically detectable cancers. The role of the immune system in fighting cancer is becoming increasingly indisputable as our understanding of its underlying mechanisms expand owing to technological advances in genomics, cancer biology, and computational sciences. In particular, significant research effort is undertaken in the field of cancer immunotherapy, where the immune system is stimulated to recognize and attack cancerous cells. In this thesis, I investigate certain aspects of the immune system in the context of cancer by computationally reconstructing and analyzing intratumoral B and T cell receptors.
Applying a novel immune cell receptor profiling protocol to original single-cell RNA sequencing (scRNA-seq) data obtained from melanoma patients, I present a complete computational reconstruction of intratumoral immune receptors in this cancer type. The scRNA-seq results are consistent with the presence of an ongoing intratumoral immune response, likely involving tertiary lymphoid structures and the cooperation between B and T cells.
Additionally, using a dataset of paired tumor biopsies collected pre- and post-treatment, I show that B cell infiltration increases after immunotherapy in pancreatic and colorectal cancer. This thesis includes the sequences of the most clonally expanded intratumoral antibodies expressed in these biopsies which I computationally reconstructed from bulk RNA sequencing reads.
Furthermore, by combining scRNA-seq and immune cell receptor profiling of samples collected from a novel mouse model, I present a comprehensive statistical analysis of gene expression in clonal tumor-reactive T cells. I also show the distribution of tumor-reactive clones across the tumor and spleen. This study forms a first proof-of-principle effort for the in-depth assessment of tumor-reactive T and B cell clones, in-vivo, and paves the way for further, more extensive experiments
A note on the products and
We prove that for any positive integer there exists a positive real number such that whenever the integer neither the product nor the product is a square
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