9,020 research outputs found

    Restoration Ecology: Two-Sex Dynamics and Cost Minimization

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    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

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    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

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    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

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    Contains reports on three research projects.United States Air Force (Contract AF19(604)-4112

    A person-oriented approach to multidimensional perfectionism: perfectionism profiles in health and well-being

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    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

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    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

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    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 H2_2O, and nitrogen dioxide NO2_2. 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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