9,020 research outputs found
Restoration Ecology: Two-Sex Dynamics and Cost Minimization
We model a spatially detailed, two-sex population dynamics, to study the cost
of ecological restoration. We assume that cost is proportional to the number of
individuals introduced into a large habitat. We treat dispersal as homogeneous
diffusion. The local population dynamics depends on sex ratio at birth, and
allows mortality rates to differ between sexes. Furthermore, local density
dependence induces a strong Allee effect, implying that the initial population
must be sufficiently large to avert rapid extinction. We address three
different initial spatial distributions for the introduced individuals; for
each we minimize the associated cost, constrained by the requirement that the
species must be restored throughout the habitat. First, we consider spatially
inhomogeneous, unstable stationary solutions of the model's equations as
plausible candidates for small restoration cost. Second, we use numerical
simulations to find the smallest cluster size, enclosing a spatially
homogeneous population density, that minimizes the cost of assured restoration.
Finally, by employing simulated annealing, we minimize restoration cost among
all possible initial spatial distributions of females and males. For biased sex
ratios, or for a significant between-sex difference in mortality, we find that
sex-specific spatial distributions minimize the cost. But as long as the sex
ratio maximizes the local equilibrium density for given mortality rates, a
common homogeneous distribution for both sexes that spans a critical distance
yields a similarly low cost
Building Damage-Resilient Dominating Sets in Complex Networks against Random and Targeted Attacks
We study the vulnerability of dominating sets against random and targeted
node removals in complex networks. While small, cost-efficient dominating sets
play a significant role in controllability and observability of these networks,
a fixed and intact network structure is always implicitly assumed. We find that
cost-efficiency of dominating sets optimized for small size alone comes at a
price of being vulnerable to damage; domination in the remaining network can be
severely disrupted, even if a small fraction of dominator nodes are lost. We
develop two new methods for finding flexible dominating sets, allowing either
adjustable overall resilience, or dominating set size, while maximizing the
dominated fraction of the remaining network after the attack. We analyze the
efficiency of each method on synthetic scale-free networks, as well as real
complex networks
How should discrepancy be assessed in perfectionism research? A psychometric analysis and proposed refinement of the Almost Perfect Scale–Revised
Research on perfectionism with the Almost Perfect Scale-Revised (APS-R) distinguishes
adaptive perfectionists versus maladaptive perfectionists based primarily on their responses to
the 12-item unidimensional APS-R discrepancy subscale, which assesses the sense of falling
short of standards. People described as adaptive perfectionists have high standards but low levels
of discrepancy (i.e., relatively close to attaining these standards). Maladaptive perfectionists have
perfectionistic high standards and high levels of discrepancy. In the current work, we re-examine
the psychometric properties of the APS-R discrepancy subscale and illustrate that this
supposedly unidimensional discrepancy measure may actually consists of more than one factor.
Psychometric analyses of data from student and community samples distinguished a pure fiveitem
discrepancy factor and a second four-item factor measuring dissatisfaction. The five-item
factor is recommended as a brief measure of discrepancy from perfection and the four-item
factor is recommended as a measure of dissatisfaction with being imperfect. Overall, our results
confirm past suggestions that most people with maladaptive perfectionism are characterized
jointly by chronic dissatisfaction as well as a sense of being discrepant due to having fallen short
of expectations. These findings are discussed in terms of their implications for the assessment of
perfectionism, as well as the implications for research and practice
Communications Biophysics
Contains reports on three research projects.United States Air Force (Contract AF19(604)-4112
Central venous to arterial carbon dioxide gap as an indicator of oxygen debt in isovolemic anemia
A person-oriented approach to multidimensional perfectionism: perfectionism profiles in health and well-being
Advances in understanding of the perfectionism construct have been limited by an almost exclusive reliance on a variable-centered approach. This study utilized a person-oriented approach to examine Hewitt and Flett’s conceptualization of multidimensional perfectionism in relation to health and well-being. Levels of conscientiousness, extraversion, and neuroticism were also assessed. Cluster analyses were employed to examine within-person configurations of self-oriented, other-oriented, and socially prescribed perfectionism (SPP) in university students (n = 538) and adults with chronic illness (n = 773). Five unique configurations were found in both samples and three clusters replicated across samples. “Extreme perfectionists” with high scores across all perfectionism dimensions reported relatively poor physical health, psychological health, psychosocial resources, and well-being along with elevated neuroticism and conscientiousness. A group distinguished by elevated SPP also reported relatively poorer outcomes along with elevated neuroticism and lower conscientiousness. In contrast, “nonperfectionists” reported relatively elevated levels of health and well-being. These profiles differed in their links with health and well-being even after taking into account key differences in conscientiousness and neuroticism. Our results illustrate the importance of employing a person-oriented approach to the study of multidimensional perfectionism, especially as it relates to physical health, mental health, and subjective well-being
Classic vs laparoscopic approach in colorectal cancer. Experience of a tertiary center, Surgery No 3 Clinic, Cluj-Napoca
Clinica Chirurgie 3, Cluj-Napoca, România, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Cancerul colorectal este unul dintre cele mai frecvente cancere și cu tendință în creștere la nivel global. Majoritatea
studiilor recente au demonstrat non inferioritatea și chiar o ușoară superioritate în abordul laparoscopic prin prisma rezultatelor
obținute și a supraviețuirii la distanță.
Material și metode: Au fost selectate retrospectiv 2186 de cazuri din baza de date completată prospectiv a Clinicii Chirurgie 3 pentru
perioada ian 2013-dec 2018 (6 ani). Din acestea s-au exclus 76 cazuri laparoscopie/laparotomie exploratorie, 154 cazuri colostomii, 51 derivații interne; în final au fost analizate 1905 cazuri de cancer colorectal.
Rezultate: Din 1905 cazuri s-au efectuat rezecții laparoscopice la un număr de 310 (16.27%) și clasice la un număr de 1595 cazuri
(83.73%). Au fost analizați între cele două loturi următorii parametri: pregătire preoperatorie, durata operației, pierderi sangvine,
complicații postoperatorii (fistulă, abces, hemoragie, ocluzie, complicații generale), supurații de plagă, zile spitalizare, necesar
antibiotic, mobilizare postoperatorie, mortalitate.
Concuzii: Abordul laparoscopic prezintă avantaje privind recuperarea postoperatorie, pierderi sangvine, zile spitalizare, necesar
antialgice/antibiotic, lipsa supurațiilor de plagă. Dezavantajele sunt curba de învățare, aparatura specifică și dificultatea păstrării
principiilor oncologice.Introduction: Colorectal cancer remains one of the most frequently diagnosed malignant pathologies with a continuously increasing
rate worldwide. Most of the recent studies have shown the non-inferiority and slight superiority in the laparoscopic approach through
obtained results.
Material and methods: 2186 cases were selected retrospectively from a prospectively completed database of the Surgical no 3
Clinic in Cluj-Napoca over the course of 6 years (ian 2013 – dec 2018). Out of these cases, 76 cases were excluded for exploratory
laparoscopy/laparotomy, 154 which underwent only colostomy, and 51 which underwent internal derivation. At the end of the study,
1905 cases were eligible.
Results: Out of 1905 cases, 310 underwent a laparoscopic approach (16.27%) and 1595 cases underwent a classic approach (83.73%).
Between the two approaches, a series of parameters were analyzed: preoperative care, duration of the surgery, intraoperative blood
loss, postoperative complications (fistula, abscess, hemorrhage, occlusion, general complications), antibiotic necessity, postoperative
mobilization, mortality, prevalence of surgical site infection.
Conclusions: The laparoscopic approach proves many advantages regarding postoperative care, blood loss, hospitalization care,
necessity of antibiotics and painkillers, and surgical site infection, cosmetic advantages. Disadvantages are the learning curve, specific
instruments requirements, difficulty of maintaining the oncology principles
Algebraic-matrix calculation of vibrational levels of triatomic molecules
We introduce an accurate and efficient algebraic technique for the
computation of the vibrational spectra of triatomic molecules, of both linear
and bent equilibrium geometry. The full three-dimensional potential energy
surface (PES), which can be based on entirely {\it ab initio} data, is
parameterized as a product Morse-cosine expansion, expressed in bond-angle
internal coordinates, and includes explicit interactions among the local modes.
We describe the stretching degrees of freedom in the framework of a Morse-type
expansion on a suitable algebraic basis, which provides exact analytical
expressions for the elements of a sparse Hamiltonian matrix. Likewise, we use a
cosine power expansion on a spherical harmonics basis for the bending degree of
freedom. The resulting matrix representation in the product space is very
sparse and vibrational levels and eigenfunctions can be obtained by efficient
diagonalization techniques. We apply this method to carbonyl sulfide OCS,
hydrogen cyanide HCN, water HO, and nitrogen dioxide NO. When we base
our calculations on high-quality PESs tuned to the experimental data, the
computed spectra are in very good agreement with the observed band origins.Comment: 11 pages, 2 figures, containg additional supporting information in
epaps.ps (results in tables, which are useful but not too important for the
paper
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