1,067 research outputs found
Cortisol levels are positively associated with pup-feeding rates in male meerkats
In societies of cooperative vertebrates, individual differences in contributions to offspring care are commonly substantial. Recent attempts to explain the causes of this variation have focused on correlations between contributions to care and the protein hormone prolactin, or the steroid hormone testosterone. However, such studies have seldom considered the importance of other hormones or controlled for non-hormonal factors that are correlative with both individual hormone levels and contributions to care. Using multivariate statistics, we show that hormone levels explain significant variation in contributions to pup-feeding by male meerkats, even after controlling for non-hormonal effects. However, long-term contributions to pup provisioning were significantly and positively correlated with plasma levels of cortisol rather than prolactin, while plasma levels of testosterone were not related to individual patterns of pup-feeding. Furthermore, a playback experiment that used pup begging calls to increase the feeding rates of male helpers gave rise to parallel increases in plasma cortisol levels, whilst prolactin and testosterone levels remained unchanged. Our findings confirm that hormones can explain significant amounts of variation in contributions to offspring feeding, and that cortisol, not prolactin, is the hormone most strongly associated with pup-feeding in cooperative male meerkats
High Temperature Electron Localization in dense He Gas
We report new accurate mesasurements of the mobility of excess electrons in
high density Helium gas in extended ranges of temperature and density to ascertain
the effect of temperature on the formation and dynamics of localized electron
states. The main result of the experiment is that the formation of localized
states essentially depends on the relative balance of fluid dilation energy,
repulsive electron-atom interaction energy, and thermal energy. As a
consequence, the onset of localization depends on the medium disorder through
gas temperature and density. It appears that the transition from delocalized to
localized states shifts to larger densities as the temperature is increased.
This behavior can be understood in terms of a simple model of electron
self-trapping in a spherically symmetric square well.Comment: 23 pages, 13 figure
Peranan Poliembrioni Terhadap Produksi Benih Pada Tanaman Jeruk Siam (Citrus nobilis L.)
This study aims to determine the growth of polyembryonic seeds in Siamese oranges and to study the growth of seedlings from polyembryonic seeds which will be used as good seeds in overcoming the problem of availability of Siamese orange seeds. The research was carried out from May to October 2022 at the Green House of the Faculty of Agriculture, Sam Ratulangi University and Eris Village, Eris District. The research method used a randomized block design (RBD) with 5 treatments repeated 4 times and found a total of 20 treatments, namely Z11, Z12, Z13, Z14, P21, P22, P23, P24, P31, P32, P33, P34, B21, B22, B23 , B24, B31, B32, B33 and B34. Data analysis used ANOVA analysis (analysis of variance). If it has no effect, then proceed with the BNT test at the 5% test level. The results showed that the growth of Siamese orange sprouts resulted in the growth of embryos up to 6 intact in one seed. Polyembryony, the ability to germinate seeds above 80.00% is one of the conditions for seeds to be recommended for seed sources 20.95%
Torque magnetometry of an amorphous-alumina/strontium-titanate interface
We report torque magnetometry measurements of an oxide heterostructure consisting of an amorphous Al2O3 thin film grown on a crystalline SrTiO3 substrate (a-AO/STO) by atomic layer deposition. We find a torque response that resembles previous studies of crystalline LaAlO3/SrTiO3 (LAO/STO) heterointerfaces, consistent with strongly anisotropic magnetic ordering in the plane of the interface. Unlike crystalline LAO, amorphous Al2O3 is nonpolar, indicating that planar magnetism at an oxide interface is possible without the strong internal electric fields generated within the polarization catastrophe model. We discuss our results in the context of current theoretical efforts to explain magnetism in crystalline LAO/STO.Chemistry and Chemical Biolog
Heat to Electricity Conversion by a Graphene Stripe with Heavy Chiral Fermions
A conversion of thermal energy into electricity is considered in the
electrically polarized graphene stripes with zigzag edges where the heavy
chiral fermion (HCF) states are formed. The stripes are characterized by a high
electric conductance Ge and by a significant Seebeck coefficient S. The
electric current in the stripes is induced due to a non-equilibrium thermal
injection of "hot" electrons. This thermoelectric generation process might be
utilized for building of thermoelectric generators with an exceptionally high
figure of merit Z{\delta}T \simeq 100 >> 1 and with an appreciable electric
power densities \sim 1 MW/cm2.Comment: 8 pages, 3 figure
Multipliers for p-Bessel sequences in Banach spaces
Multipliers have been recently introduced as operators for Bessel sequences
and frames in Hilbert spaces. These operators are defined by a fixed
multiplication pattern (the symbol) which is inserted between the analysis and
synthesis operators. In this paper, we will generalize the concept of Bessel
multipliers for p-Bessel and p-Riesz sequences in Banach spaces. It will be
shown that bounded symbols lead to bounded operators. Symbols converging to
zero induce compact operators. Furthermore, we will give sufficient conditions
for multipliers to be nuclear operators. Finally, we will show the continuous
dependency of the multipliers on their parameters.Comment: 17 page
Structural and superconducting properties of MgBBe
We prepared MgBBe (, 0.2, 0.3, 0.4, and 0.6) samples where
B is substituted with Be. MgB structure is maintained up to .
In-plane and inter-plane lattice constants were found to decrease and increase,
respectively. Superconducting transition temperature decreases with
. We found that the decrease is correlated with in-plane contraction
but is insensitive to carrier doping, which is consistent with other
substitution studies such as MgAlB and MgBC.
Implication of this work is discussed in terms of the 2D nature of -band.Comment: 3 pages,4 figures, to be published in Phys. Rev.
Automatic initialization and quality control of large-scale cardiac MRI segmentations
Continuous advances in imaging technologies enable ever more comprehensive phenotyping of human anatomy and physiology. Concomitant reduction of imaging costs has resulted in widespread use of imaging in large clinical trials and population imaging studies. Magnetic Resonance Imaging (MRI), in particular, offers one-stop-shop multidimensional biomarkers of cardiovascular physiology and pathology. A wide range of analysis methods offer sophisticated cardiac image assessment and quantification for clinical and research studies. However, most methods have only been evaluated on relatively small databases often not accessible for open and fair benchmarking. Consequently, published performance indices are not directly comparable across studies and their translation and scalability to large clinical trials or population imaging cohorts is uncertain. Most existing techniques still rely on considerable manual intervention for the initialization and quality control of the segmentation process, becoming prohibitive when dealing with thousands of images. The contributions of this paper are three-fold. First, we propose a fully automatic method for initializing cardiac MRI segmentation, by using image features and random forests regression to predict an initial position of the heart and key anatomical landmarks in an MRI volume. In processing a full imaging database, the technique predicts the optimal corrective displacements and positions in relation to the initial rough intersections of the long and short axis images. Second, we introduce for the first time a quality control measure capable of identifying incorrect cardiac segmentations with no visual assessment. The method uses statistical, pattern and fractal descriptors in a random forest classifier to detect failures to be corrected or removed from subsequent statistical analysis. Finally, we validate these new techniques within a full pipeline for cardiac segmentation applicable to large-scale cardiac MRI databases. The results obtained based on over 1200 cases from the Cardiac Atlas Project show the promise of fully automatic initialization and quality control for population studies
A Green's function approach to transmission of massless Dirac fermions in graphene through an array of random scatterers
We consider the transmission of massless Dirac fermions through an array of
short range scatterers which are modeled as randomly positioned -
function like potentials along the x-axis. We particularly discuss the
interplay between disorder-induced localization that is the hallmark of a
non-relativistic system and two important properties of such massless Dirac
fermions, namely, complete transmission at normal incidence and periodic
dependence of transmission coefficient on the strength of the barrier that
leads to a periodic resonant transmission. This leads to two different types of
conductance behavior as a function of the system size at the resonant and the
off-resonance strengths of the delta function potential. We explain this
behavior of the conductance in terms of the transmission through a pair of such
barriers using a Green's function based approach. The method helps to
understand such disordered transport in terms of well known optical phenomena
such as Fabry Perot resonances.Comment: 22 double spaced single column pages. 15 .eps figure
Photonic realization of the relativistic Kronig-Penney model and relativistic Tamm surface states
Photonic analogues of the relativistic Kronig-Penney model and of
relativistic surface Tamm states are proposed for light propagation in fibre
Bragg gratings (FBGs) with phase defects. A periodic sequence of phase slips in
the FBG realizes the relativistic Kronig-Penney model, the band structure of
which being mapped into the spectral response of the FBG. For the semi-infinite
FBG Tamm surface states can appear and can be visualized as narrow resonance
peaks in the transmission spectrum of the grating
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