1,031 research outputs found

    Lazarus ecology: Recovering the distribution and migratory patterns of the extinct Carolina parakeet.

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    The study of the ecology and natural history of species has traditionally ceased when a species goes extinct, despite the benefit to current and future generations of potential findings. We used the extinct Carolina parakeet as a case study to develop a framework investigating the distributional limits, subspecific variation, and migratory habits of this species as a means to recover important information about recently extinct species. We united historical accounts with museum collections to develop an exhaustive, comprehensive database of every known occurrence of this once iconic species. With these data, we combined species distribution models and ordinal niche comparisons to confront multiple conjectured hypotheses about the parakeet's ecology with empirical data on where and when this species occurred. Our results demonstrate that the Carolina parakeet's range was likely much smaller than previously believed, that the eastern and western subspecies occupied different climatic niches with broad geographical separation, and that the western subspecies was likely a seasonal migrant while the eastern subspecies was not. This study highlights the novelty and importance of collecting occurrence data from published observations on extinct species, providing a starting point for future investigations of the factors that drove the Carolina parakeet to extinction. Moreover, the recovery of lost autecological knowledge could benefit the conservation of other parrot species currently in decline and would be crucial to the success of potential de-extinction efforts for the Carolina parakeet

    Hamiltonian LGT in the complete Fourier analysis basis

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    The main problem in the Hamiltonian formulation of Lattice Gauge Theories is the determination of an appropriate basis avoiding the over-completeness arising from Mandelstam relations. We short-cut this problem using Harmonic analysis on Lie-Groups and intertwining operators formalism to explicitly construct a basis of the Hilbert space. Our analysis is based only on properties of the tensor category of Lie-Group representations. The Hamiltonian of such theories is calculated yielding a sparse matrix whose spectrum and eigenstates could be exactly derived as functions of the coupling g2g^2Comment: LATTICE99 (theoretical developments), 3 page

    The Equation of State of Dense Matter : from Nuclear Collisions to Neutron Stars

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    The Equation of State (EoS) of dense matter represents a central issue in the study of compact astrophysical objects and heavy ion reactions at intermediate and relativistic energies. We have derived a nuclear EoS with nucleons and hyperons within the Brueckner-Hartree-Fock approach, and joined it with quark matter EoS. For that, we have employed the MIT bag model, as well as the Nambu--Jona-Lasinio (NJL) and the Color Dielectric (CD) models, and found that the NS maximum masses are not larger than 1.7 solar masses. A comparison with available data supports the idea that dense matter EoS should be soft at low density and quite stiff at high density.Comment: 8 pages, 5 figures, invited talk given at NPA3, Dresden, March 200

    Spinodal instabilities within BUU approach

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    Using a recently developed method for the inclusion of fluctuation in the BUU dynamics, we study the self-consistent propagation of inherent thermal noise of unstable nuclear matter. The large time behaviour of the evolving system exhibits synergism between fluctuation and non-linearities in a universal manner which manifest in the appearance of macroscopic structure in the average description.Comment: 12 pages Revtex. Two figures, uuencoded, are enclosed in a separate fil

    Protoneutron stars in the Brueckner-Hartree-Fock approach and finite-temperature kaon condensation

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    We study the properties of hot neutrino-trapped beta-stable stellar matter using an equation of state of nuclear matter within the Brueckner-Hartree-Fock approach including three-body forces, combined with a standard chiral model for kaon condensation at finite temperature. The properties of (proto)neutron stars are then investigated within this framework.Comment: 10 pages, 5 figures, 2 tables, PRC in pres

    Evidenze altomedievali nelle valli dei fiumi Torto e Imera settentrionale

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    Si illustrano i risultati relativi al periodo altomedievale nell'area della Sicilia centro-settentrionale corrispondente ai bacini dei fiumi Torto e Imera settentrionale. I dati archeologici, frutto delle prospezioni qui condotte, testimoniano forme di popolamento rurale sparso, con poche eccezioni rappresentate da siti egemoni

    Seasonal plumage condition variation and the thermal value of the feather coats of house sparrows (Passer domesticus)

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    Feathers are critical to how birds thermoregulate, and thus their total energy balance. The feather coat insulates birds by trapping air next to the skin and acting as a physical barrier to heat loss. Despite previous work studying thermal balance in birds, relatively few studies have focused on the thermal contribution of the feather coat alone; most studies have focused on physiological and behavioral responses. Moreover, to our knowledge, no studies have directly measured the effect of feather wear through the annual cycle on the thermal performance of the feather coat. To address this, we used a thermal camera to measure the temperature at the surface of the feather coat of live house sparrows (Passer domesticus) in winter (post-molt, unworn feathers) and summer (pre-molt, worn feathers), as well as flat-skins of the same specimens in order to isolate the thermal effect of the feather coat alone. We predicted that worn feather coats would lose more heat than unworn feather coats in both live birds and flat skins. Surprisingly, we found that feather wear had no effect on the thermal performance of the feather coat across seasons. The thermal balance of birds will be better understood when the thermal contribution of the feather coat is directly measured across more species and conditions

    A study of maternal competence in preterm birth condition, during the transition from hospital to home: An early intervention program’s proposal

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    The study was conducted with 104 mothers (average age 32.5 years, SD 6.1) of preterm infants (very and moderately preterm but still healthy) to monitor the perceived maternal role competence from the time of hospitalisation to post-discharge, in order to define an intervention program to support mothers during this transition. A targeted Q-Sort tool (Maternal Competence Q-Sort in preterm birth) was applied at two different times as a self-observation tool for parenting competence in neonatology. A tendency towards dysregulation of the maternal role competence was detected, mainly in terms of low self-assessment and was found to worsen during post-discharge, particularly with regard to caregiving ability. This study suggests the importance of accompanying parenting competence in preterm birth conditions, not only during hospitalisation in the Neonatal Intensive Care Unit (NICU) but also following discharge in order to promote the development of premature infants. This paper reports in the last part a specific integrated psychoeducational intervention program (psychologist and nurses), which we defined precisely in light of the suggestions offered by the study data on perceived maternal competence created with the Q-sort

    LIMB BODY WALL COMPLEX IN TWO HETEROZYGOTIC TWINS: A CASE REPORT

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    Introdution. Limb-Body Wall Complex (LBWC) is a congenital defect which includes at least two of the following characteristics: abdominal and/or thoracic body wall defects, exencephaly or encephalocoele with or without craniofacial defects (56%) and spinal defects associated with marked vertebral or sacral defects (95%). Case Report. We present a case report of an infant with LBWC, borned by diamniotic twin pregnancy. A prenatal ultrasound reported an healthy fetus and a fetus with multiple malformations. At birth we found a big abdominal wall defect, absence of scrotal sac and testicles, asymmetric chest and no major deformities in craniofacial region. At 2 hours of life, we removed the amniotic sac, we put the stomach and the spleen in the abdominal cavity, which is virtual, and positioned a spring-loaded silo. At 15th day of life we had complete reduction of the intestinal loops and liver and we closed the wall defect with a prosthesis and a cryopreserved skin. The general conditions of the patient, very severe since birth, became progressively worse and he died in the 21st day of life. Discussion. Once the diagnosis is done the physician should offer the parents a therapeutic abortion, and above all, in case they want to carry the pregnancy to term, we need to prepare them to the severity of the malformation and the high probability of death
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