623 research outputs found
Revision of Madagascar's Dwarf Lemurs (Cheirogaleidae:Cheirogaleus): Designation of Species, Candidate Species Status and Geographic Boundaries Based on Molecular and Morphological Data
The genus Cheirogaleus, the dwarf lemurs, is a radiation of strepsirrhine primates endemic to the island of Madagascar.
The dwarf lemurs are taxonomically grouped in the family Cheirogaleidae (Infraorder: Lemuriformes) along with the genera
Microcebus, Mirza, Allocebus, and Phaner. The taxonomic history of the genus Cheirogaleus has been controversial since its
inception due to a paucity of evidence in support of some proposed species. In this study, we addressed this issue by expanding the
geographic breadth of samples by 91 individuals and built upon existing mitochondrial (cytb and COII) and nuclear (FIBA and
vWF) DNA datasets to better resolve the phylogeny of Cheirogaleus. The mitochondrial gene fragments D-loop and PAST as well
as the CFTR-PAIRB nuclear loci were also sequenced. In agreement with previous genetic studies, numerous deep divergences
were resolved in the C. major, C. minor and C. medius lineages. Four of these lineages were segregated as new species, seven
were identified as confirmed candidate species, and four were designated as unconfirmed candidate species based on comparative
mitochondrial DNA sequence data gleaned from the literature or this study. Additionally, C. thomasi was resurrected. Given the
widespread distribution of the genus Cheirogaleus throughout Madagascar, the methodology employed in this study combined
all available lines of evidence to standardize investigative procedures in a genus with limited access to type material and a lack of
comprehensive sampling across its total distribution. Our results highlighted lineages that likely represent new species and identified
localities that may harbor an as-yet undescribed cryptic species diversity pending further field and laboratory work.We
are most grateful to the Ahmanson Foundation, the Theodore
F. and Claire M. Hubbard Family Foundation, the Primate
Action Fund / Conservation International, the Margot
Marsh Biodiversity Foundation, and the National Geographic
Society, for financial assistance
Neutron Transfer Dynamics and Doorway to Fusion in Time-Dependent Hartree-Fock Theory
We analyze the details of mass exchange in the vicinity of the Coulomb
barrier for heavy-ion collisions involving neutron-rich nuclei using the
time-dependent Hartree-Fock (TDHF) theory. We discuss the time-dependence of
transfer and show that the potential barriers seen by individual
single-particle states can be considerably different than the effective barrier
for the two interacting nuclei having a single center-of-mass. For this reason
we observe a substantial transfer probability even at energies below the
effective barrier.Comment: 6 pages, 9 figure
Prospects of combined antihypertensive-psychocorrective therapy in women with arterial hypertension and anxiety-depressive disorders: clinical randomized placebo uncontrolled trial
Background. Anxiety-depressive disorders (ADD) afflict almost half of patients with arterial hypertension (AH). AH aggravation by psychoemotional disorders causes a more severe illness and rapid target organ injury, particularly, the increased arterial stiffness and central aortic pressure (CAP). However, the prospects of combined antihypertensive-antidepressant treatments in AH-ADD patients remain largely unexplored.Objectives. The effect assessment in combined antihypertensive-psychocorrective therapy on circadian blood pressure (BP), vascular stiffness and CAP, anxiety and depression in women with AH and ADD.Methods. The study enrolled 60 AH-ADD women randomised between two cohorts. Cohort 1 received a fixed combination of valsartan and hydrochlorothiazide, bisoprolol and sertraline antidepressant; cohort 2 only had same combined AH therapy. Past 24 weeks of trial, all patients had a general clinical examination and daily blood pressure monitoring (DBPM) with BpLab Vasotens (Petr Telegin Ltd., Russia) and control of daily BP, CAP and vascular stiffness. The psychometric HADS and CES-D scales were used along with psychiatric counselling.Results. Past four weeks of treatment, the target blood pressure (TBP) was revealed in 60 and 36.7% patients, and in 90 and 66.6% — past eight weeks in cohorts 1 and 2, respectively. Cohort 1 vs. 2 required a lower valsartan dose to attain TBP. Past six months, both cohorts showed improved main DBPM values reflecting vascular stiffness and CAP. However, a statistical decrease in nocturnal central and peripheral BP, as well as improved BP variability and vascular stiffness were registered at antidepressant use. A normalised daily BP profile was significantly more frequent in cohort 1. In addition, sertraline had a significant ADD-reductive impact.Conclusion. An antidepressant-combined conventional AH therapy in AH-ADD women facilitated a faster TBP achievement at lower AH agent doses and the significantly improved DBPM (nocturnal specifically), arterial stiffness and CAP values. A sertraline treatment improved the psychoemotional patient state
Beta-decay of nuclei around Se-90. Search for signatures of a N=56 sub-shell closure relevant the r-process
Nuclear structure plays a significant role on the rapid neutron capture
process (r-process) since shapes evolve with the emergence of shells and
sub-shells. There was some indication in neighboring nuclei that we might find
examples of a new N=56 sub-shell, which may give rise to a doubly magic Se-90
nucleus. Beta-decay half lives of nuclei around Se-90 have been measured to
determine if this nucleus has in fact a doubly-magic character. The
fragmentation of Xe-136 beam at the National Superconducting Cyclotron
Laboratory at Michigan State University was used to create a cocktail of nuclei
in the A=90 region. We have measured the half lives of twenty-two nuclei near
the r-process path in the A=90 region. The half lives of As-88 and Se-90 have
been measured for the first time. The values were compared with theoretical
predictions in the search for nuclear-deformation signatures of a N=56
sub-shell, and its possible role in the emergence of a potential doubly-magic
Se-90. The impact of such hypothesis on the synthesis of heavy nuclei,
particularly in the production of Sr, Y and Zr elements was investigated with a
weak r-process network. The new half lives agree with results obtained from a
standard global QRPA model used in r-process calculations, indicating that
Se-90 has a quadrupole shape incompatible with a closed N=56 sub-shell in this
region. The impact of the measured Se-90 half-life in comparison with a former
theoretical predication associated with a spherical half-life on the
weak-r-process is shown to be strong
Comparative Analysis of the Flexural Stiffness of Pinniped Vibrissae
Vibrissae are important components of the mammalian tactile sensory system and are used to detect vibrotactile stimuli in the environment. Pinnipeds have the largest and most highly innervated vibrissae among mammals, and the hair shafts function as a biomechanical filter spanning the environmental stimuli and the neural mechanoreceptors deep in the follicle-sinus complex. Therefore, the material properties of these structures are critical in transferring vibrotactile information to the peripheral nervous system. Vibrissae were tested as cantilever beams and their flexural stiffness (EI) was measured to test the hypotheses that the shape of beaded vibrissae reduces EI and that vibrissae are anisotropic. EI was measured at two locations on each vibrissa, 25% and 50% of the overall length, and at two orientations to the point force. EI differed in orientations that were normal to each other, indicating a functional anisotropy. Since vibrissae taper from base to tip, the second moment of area (I) was lower at 50% than 25% of total length. The anterior orientation exhibited greater EI values at both locations compared to the dorsal orientation for all species. Smooth vibrissae were generally stiffer than beaded vibrissae. The profiles of beaded vibrissae are known to decrease the amplitude of vibrations when protruded into a flow field. The lower EI values of beaded vibrissae, along with the reduced vibrations, may function to enhance the sensitivity of mechanoreceptors to detection of small changes in flow from swimming prey by increasing the signal to noise ratio. This study builds upon previous morphological and hydrodynamic analyses of vibrissae and is the first comparative study of the mechanical properties of pinniped vibrissae.The open access fee for this work was funded through the Texas A&M University Open Access to Knowledge (OAK) Fund
Cross Section Limits for the Pb(Kr,n)118 Reaction
In April-May, 2001, the previously reported experiment to synthesize element
118 using the Pb(Kr,n)118 reaction was repeated. No
events corresponding to the synthesis of element 118 were observed with a total
beam dose of 2.6 x 10 ions. The simple upper limit cross sections (1
event) were 0.9 and 0.6 pb for evaporation residue magnetic rigidities of 2.00
and 2.12 , respectively. A more detailed cross section calculation,
accounting for an assumed narrow excitation function, the energy loss of the
beam in traversing the target and the uncertainty in the magnetic rigidity of
the Z=118 recoils is also presented. Re-analysis of the primary data files from
the 1999 experiment showed the reported element 118 events are not in the
original data. The current results put constraints on the production cross
section for synthesis of very heavy nuclei in cold fusion reactions.Comment: 7 pages, 2 figures. Submitted to EPJ
Beta-delayed proton emission in the 100Sn region
Beta-delayed proton emission from nuclides in the neighborhood of 100Sn was
studied at the National Superconducting Cyclotron Laboratory. The nuclei were
produced by fragmentation of a 120 MeV/nucleon 112Sn primary beam on a Be
target. Beam purification was provided by the A1900 Fragment Separator and the
Radio Frequency Fragment Separator. The fragments of interest were identified
and their decay was studied with the NSCL Beta Counting System (BCS) in
conjunction with the Segmented Germanium Array (SeGA). The nuclei 96Cd, 98Ing,
98Inm and 99In were identified as beta-delayed proton emitters, with branching
ratios bp = 5.5(40)%, 5.5+3 -2%, 19(2)% and 0.9(4)%, respectively. The bp for
89Ru, 91,92Rh, 93Pd and 95Ag were deduced for the first time with bp = 3+1.9
-1.7%, 1.3(5)%, 1.9(1)%, 7.5(5)% and 2.5(3)%, respectively. The bp = 22(1)% for
101Sn was deduced with higher precision than previously reported. The impact of
the newly measured bp values on the composition of the type-I X-ray burst ashes
was studied.Comment: 15 pages, 14 Figures, 4 Table
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