2,138 research outputs found
Placentophagia in Nonpregnant Rats:\ud Influence of Estrous Cycle Stage and Birthplace
Prior parturitional experience and genotype have previously been found to affect the proportion of nonpregnant female rats and mice that will eat foster placenta. The present series of experiments was designed to investigate the influence of estrous cycle stage on placentophagia in rats. Foster placenta was presented to nonpregnant Long-Evans females, purchased from a commercial breeder, for 15 min on 5 consecutive days. We found that virgin placentophages were most likely to have eaten placenta on the first presentation, unless the first presentation occurred during proestrus. In fact, virgins would not eat placenta for the first time during proestrus, regardless of test-day. However, once they had eaten placenta, either in a nonproestrus stage, or, in the case of primiparae, during parturition, they would eat placenta during proestrus. Long-Evans rats born in our laboratory differed from the purchased rats, manifesting an incidence of placentophagia that was too low to be analyzed by stage of the estrous cycle; when tested as primiparae, however, there were no differences between the two groups
Response of Feedlot Lambs to Chlortetracycline and Sulfamethazine
The objective of this experiment was to test the effects of chlortetracycline and sulfamethazine alone and in combination on feedlot performance and incidence of diseases of lambs weaned at an early age, shipped and finished in drylot with a high-concentrate ration
Uterine distention facilitates the onset of maternal behavior in pseudopregnant but not in cycling rats
The latency to onset of maternal behavior toward foster pups was examined in maternally-naive female rats treated either with uterine distention, a sham procedure, or no uterine manipulation. Uterine distention was achieved by intrauterine injection of hypertonic saline. The treatments were applied to either cycling, Day 10 pseudopregnant, or Day 11 pseudopregnant-decidualized virgins. The latency to onset of maternal behavior for both pseudopregnant groups was significantly shorter than that for the nonpseudopregnant group, when uterine distention was applied. The results suggest that uterine distention during pregnancy (during high progesterone level) may bring about both pregnancy termination (delivery) and the almost immediate maternal behavior seen at parturition, by the same hormonal mechanism
Gate-defined graphene double quantum dot and excited state spectroscopy
A double quantum dot is formed in a graphene nanoribbon device using three
top gates. These gates independently change the number of electrons on each dot
and tune the inter-dot coupling. Transport through excited states is observed
in the weakly coupled double dot regime. We extract from the measurements all
relevant capacitances of the double dot system, as well as the quantized level
spacing
Enhancement of tissue lesion depth by dual wavelength irradiation with the Nd-YAG/KTP laser: Perspectives for laser prostatectomy
The Nd-YAG/KTP laser coagulates and vaporizes prostate tissue. The objective of this study was to investigate the combined effects of both wavelengths and to determine the irradiation parameters allowing the largest lesion volume. Chicken breast tissue was irradiated ex vivo. Consecutive 1064 and 532 nm Nd-YAG/KTP laser irradiations were performed for different combinations (30 W/10 W, 20 W/20 W, 10 W/30 W) with variable total fluence (1200 J, 2400 J, 3600 J) and compared to isofluent single wavelengths at 40 W irradiation. The depths, diameters and volumes of the total lesion as well as the vaporization effects of the 532 nm wavelength on normal and on priorly coagulated tissue were analysed. Maximum total lesion depths (p< 0.001) were found under combined Nd-YAG/KTP (20 W/20 W) irradiation conditions. Ablation efficacy of the 532 nm wavelength was reduced after prior 1064 nm irradiation, but crater depths were increased. Dual wavelength irradiation with the Nd-YAG/KTP laser induces a specific denaturation process. This may represent a new approach to increase the depth of coagulation necrosis, and thus the treated volume, thereby improving long-term result
Orientifolds, Unoriented Instantons and Localization
We consider world-sheet instanton effects in N=1 string orientifolds of
noncompact toric Calabi-Yau threefolds. We show that unoriented closed string
topological amplitudes can be exactly computed using localization techniques
for holomorphic maps with involution. Our results are in precise agreement with
mirror symmetry and large N duality predictions.Comment: 25 pages, 10 figures, published version; v4: typos correcte
PU(2) monopoles. II: Top-level Seiberg-Witten moduli spaces and Witten's conjecture in low degrees
In this article we complete the proof---for a broad class of
four-manifolds---of Witten's conjecture that the Donaldson and Seiberg-Witten
series coincide, at least through terms of degree less than or equal to c-2,
where c is a linear combination of the Euler characteristic and signature of
the four-manifold. This article is a revision of sections 4--7 of an earlier
version, while a revision of sections 1--3 of that earlier version now appear
in a separate companion article (math.DG/0007190). Here, we use our
computations of Chern classes for the virtual normal bundles for the
Seiberg-Witten strata from the companion article (math.DG/0007190), a
comparison of all the orientations, and the PU(2) monopole cobordism to compute
pairings with the links of level-zero Seiberg-Witten moduli subspaces of the
moduli space of PU(2) monopoles. These calculations then allow us to compute
low-degree Donaldson invariants in terms of Seiberg-Witten invariants and
provide a partial verification of Witten's conjecture.Comment: Journal fur die Reine und Angewandte Mathematik, to appear; 65 pages.
Revision of sections 4-7 of version v1 (December 1997
Depinning transition of a directed polymer by a periodic potential: a d-dimensional solution
We study the depinning phase transition of a directed polymer in a
-dimensional space by a periodic potential localized on a straight line. We
give exact formulas in all dimensions for the critical pinning we need to
localize the polymer. We show that a bounded state can still arise even if, in
average, the potential layer is not attractive and for diverging values of the
potential on the repulsive sites. The phase transition is of second order.Comment: 11 Pages in LaTeX. Figures available from the authors.
[email protected] (e-mail address
The holomorphic anomaly for open string moduli
We complete the holomorphic anomaly equations for topological strings with
their dependence on open moduli. We obtain the complete system by standard path
integral arguments generalizing the analysis of BCOV (Commun. Math. Phys. 165
(1994) 311) to strings with boundaries. We study both the anti-holomorphic
dependence on open moduli and on closed moduli in presence of Wilson lines. By
providing the compactification a' la Deligne-Mumford of the moduli space of
Riemann surfaces with boundaries, we show that the open holomorphic anomaly
equations are structured on the (real codimension one) boundary components of
this space.Comment: 1+14 pages, 6 figures! v2: ref. added v3: section 4 expanded, 1+17
pages, 11 figures!!, to be publ. in JHE
Time- and momentum-resolved probe of heat transport in photo-excited bismuth
We use time- and momentum-resolved x-ray scattering to study thermalization in a photo-excited thin single crystal bismuth film on sapphire. The time-resolved changes of the diffuse scattering show primarily a quasi-thermal phonon distribution that is established in less than or similar to 100 ps and that follows the time-scale of thermal transport. Ultrafast melting measurements under high laser excitation show that epitaxial regrowth of the liquid phase occurs on the time-scale of thermal transport across the bismuth-sapphire interface. (C) 2013 AIP Publishing LLC. (DOI: 10.1063/1.4804291
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