543 research outputs found
American Red Cross
The American Red Cross has been plagued with problems over the past two years from an antitrust lawsuit, repercussions from the distributions of funds from the Liberty Fund to the survivors of the World Trade Center disaster, problems with donated blood, a negative report from the Better Business Bureau, and a negative news report on CBS’s ’60 Minutes’. This case study looks at the history of the Red Cross, provides information about the services provided by the organization, discusses the problems the American Red Cross has encountered over the past 3 years, and introduces Marsha Evans who took the position of CEO in August 2002
Component graphs of vector spaces and zero-divisor graphs of ordered sets
In this paper, nonzero component graphs and nonzero component union graphs of
finite dimensional vector space are studied using the zero-divisor graph of
specially constructed 0-1-distributive lattice and the zero-divisor graph of
rings. Further, we define an equivalence relation on nonzero component graphs
and nonzero component union graphs to deduce that these graphs are the graph
join of zero-divisor graphs of Boolean algebras and complete graphs. In the
last section, we characterize the perfect and chordal nonzero component graphs
and nonzero component union graphs.Comment: arXiv admin note: text overlap with arXiv:2205.0491
The Role of Context in the Evolution of a Serial Entrepreneur
Entrepreneurial research often focuses on the psychological traits of the entrepreneur but rarely on the notion that under certain circumstances entrepreneurship may be equally driven by external factors beyond the founder's control. This paper looks at the 40-year history of a serial entrepreneur and identifies five types of business ventures driven by contextual factors and the personal attributes of the entrepreneur. These five types are the “advised” venture, the “safe harbor” venture, the “accidental” venture, the “greener grass” venture, and the “passion” venture. The paper closes with a call for future research to include situational context in defining what creates and motivates entrepreneurs
On the Hamiltonian structure of Ermakov systems
A canonical Hamiltonian formalism is derived for a class of Ermakov systems
specified by several different frequency functions. This class of systems
comprises all known cases of Hamiltonian Ermakov systems and can always be
reduced to quadratures. The Hamiltonian structure is explored to find exact
solutions for the Calogero system and for a noncentral potential with dynamic
symmetry. Some generalizations of these systems possessing exact solutions are
also identified and solved
Snail Homing and Mating Search Algorithm: A Novel Bio-Inspired Metaheuristic Algorithm
In this paper, a novel Snail Homing and Mating Search (SHMS) algorithm is
proposed. It is inspired from the biological behaviour of the snails. Snails
continuously travels to find food and a mate, leaving behind a trail of mucus
that serves as a guide for their return. Snails tend to navigate by following
the available trails on the ground and responding to cues from nearby shelter
homes. The proposed SHMS algorithm is investigated by solving several unimodal
and multimodal functions. The solutions are validated using standard
statistical tests such as two-sided and pairwise signed rank Wilcoxon test and
Friedman rank test. The solution obtained from the SHMS algorithm exhibited
superior robustness as well as search space exploration capabilities within the
less computational cost. The real-world application of SHMS algorithm is
successfully demonstrated in the engineering design domain by solving three
cases of design and economic optimization shell and tube heat exchanger
problem. The objective function value and other statistical results obtained
using SHMS algorithm are compared with other well-known metaheuristic
algorithms.Comment: 46 Pages, 11 Figures, 24 Table
Decrease in hyperosmotic stress-induced corneal epithelial cell apoptosis by L-carnitine
Purpose: To characterize the osmoprotective properties of L-carnitine on human corneal epithelial cell volume and apoptosis during hyperosmotic stress.
Methods: Human corneal limbal epithelial (HCLE) cells were exposed to culture medium at 300 mOsm (isotonic) or 500 mOsm (hyperosmotic) with or without L-carnitine (10 mM). Induction of apoptosis was detected by quantifying the proteolytic activity of caspase-8, caspase-9, and caspase-3/7 using caspase activity assays, the expression of tumor necrosis factor (TNF)-α with enzyme-linked immunosorbent assay, and annexin V/propidium iodide staining of HCLE cells evaluated with confocal microscopy and flow cytometry. Cell volume changes in response to hyperosmotic stress were analyzed using flow cytometry.
Results: After the HCLE cells were exposed to hyperosmotic medium (500 mOsm), the percentage of shrunken cells and damaged/dead cells (stained positively for annexin V and/or propidium iodide) was six- and three-fold, respectively, higher than that under isotonic conditions (300 mOsm). This was paralleled by an increase in TNF-α concentration in media and caspase-8, -9, and -3/7 activities (six-, four-, ten-, and twelve-fold, respectively; all showing p\u3c0.001). AddiÂtion of L-carnitine during hyperosmotic stress partly restored cell volume and significantly reduced the concentration of TNF-α released (p=0.005) and caspase-9 activity (p=0.0125). Addition of L-carnitine reduced the percentage of hyperosmolarity-induced damaged/dead cells to levels observed under isotonic conditions
Thresholded Covering Algorithms for Robust and Max-Min Optimization
The general problem of robust optimization is this: one of several possible
scenarios will appear tomorrow, but things are more expensive tomorrow than
they are today. What should you anticipatorily buy today, so that the
worst-case cost (summed over both days) is minimized? Feige et al. and
Khandekar et al. considered the k-robust model where the possible outcomes
tomorrow are given by all demand-subsets of size k, and gave algorithms for the
set cover problem, and the Steiner tree and facility location problems in this
model, respectively.
In this paper, we give the following simple and intuitive template for
k-robust problems: "having built some anticipatory solution, if there exists a
single demand whose augmentation cost is larger than some threshold, augment
the anticipatory solution to cover this demand as well, and repeat". In this
paper we show that this template gives us improved approximation algorithms for
k-robust Steiner tree and set cover, and the first approximation algorithms for
k-robust Steiner forest, minimum-cut and multicut. All our approximation ratios
(except for multicut) are almost best possible.
As a by-product of our techniques, we also get algorithms for max-min
problems of the form: "given a covering problem instance, which k of the
elements are costliest to cover?".Comment: 24 page
On the complexity of reliable communication on the erasure channel
We discuss the complexity of achieving channel capacity on the binary erasure channel (BEC) in view of recent advances. We also extrapolate to conjecture complexity bounds on more general channels
Area distribution of two-dimensional random walks on a square lattice
The algebraic area probability distribution of closed planar random walks of
length N on a square lattice is considered. The generating function for the
distribution satisfies a recurrence relation in which the combinatorics is
encoded. A particular case generalizes the q-binomial theorem to the case of
three addends. The distribution fits the L\'evy probability distribution for
Brownian curves with its first-order 1/N correction quite well, even for N
rather small.Comment: 8 pages, LaTeX 2e. Reformulated in terms of q-commutator
- …