3,167 research outputs found
Uncertainty in Measurements of Distance
Ng and van Dam have argued that quantum theory and general relativity give a
lower bound of L^{1/3} L_P^{2/3} on the uncertainty of any distance, where L is
the distance to be measured and L_P is the Planck length. Their idea is roughly
that to minimize the position uncertainty of a freely falling measuring device
one must increase its mass, but if its mass becomes too large it will collapse
to form a black hole. Here we show that one can go below the Ng-van Dam bound
by attaching the measuring device to a massive elastic rod. Relativistic
limitations on the rod's rigidity, together with the constraint that its length
exceeds its Schwarzschild radius, imply that zero-point fluctuations of the rod
give an uncertainty greater than or equal to L_P.Comment: 5 pages LaTe
Effects of infrequent dried distillers grain supplementation on spring-calving cow performance
Feed and supplement costs and the expenses associated with delivery of winter supplements
account for a large proportion of the total operating expenditures for cow-calf
producers. Cattle grazing low-quality dormant native range (<6% crude protein) typically
are unable to consume sufficient protein from the forage base, which limits microbial
activity and forage digestion. Supplemental protein often is required to maintain
cow body weight and body condition score during the last trimester of pregnancy. Low
cow body condition scores at calving are common and may negatively affect lactation,
rebreeding rates, and calf weaning weight. Failure to maintain proper nutritional status
during this period severely affects short-term cow performance, reduces overall herd
productivity, and limits profit potential.
The most effective means of supplying supplemental protein to cows consuming
dormant native range is to provide a small amount of high-protein feedstuff (>30%
crude protein). Dried distillers grains with solubles (DDGS) are a by-product of the
ethanol refining process. Distillers grains supply the recommended 30% crude protein
level, are readily available, and often are favorably priced compared with more traditional
feedstuffs.
With the rising costs of inputs in today’s cow-calf sector, reducing cost is necessary to
maintain viability of the national cowherd. Reducing the frequency of supplementation
results in less labor and fuel use, effectively reducing input costs; however, this is viable
only as long as cow performance is maintained at acceptable levels. Therefore, the objective
of this study was to examine the effects of infrequent supplementation of dried
distillers grains with solubles on cow body weight and body condition score
Calf health and performance during receiving is not changed by fence-line preconditioning on flint hills range vs. drylot preconditioning
Ranch-of-origin preconditioning can improve the welfare and performance of beef
calves by decreasing the stress associated with weaning, transport, diet change, and
commingling with other calves. Preconditioning methods that involve pasture weaning
coupled with maternal contact (i.e., fence-line weaning) have been promoted as possible
best management practices for minimizing stress. Prior studies focused on performance
and behavior during preconditioning on the ranch of origin. Little information has
been published relating to carryover effects of fence-line preconditioning compared
with conventional drylot preconditioning on performance and behavior during feedlot
receiving.
Our objectives were to measure growth and health during a 28-day ranch-of-origin
preconditioning phase and during a 60-day feedlot receiving phase among beef calves
subjected to 1 of 3 ranch-of-origin preconditioning programs: (1) drylot preconditioning
+ dam separation, (2) pasture preconditioning + fence-line contact with dams, and
(3) pasture preconditioning + fence-line contact with dams + supplemental feed delivered
in a bunk. In addition, we recorded incidences of behavioral distress among these
treatments during first 7 days of feedlot receiving
Nonequilibrium Approach to Bloch-Peierls-Berry Dynamics
We examine the Bloch-Peierls-Berry dynamics under a classical nonequilibrium
dynamical formulation. In this formulation all coordinates in phase space
formed by the position and crystal momentum space are treated on equal footing.
Explicitly demonstrations of the no (naive) Liouville theorem and of the
validity of Darboux theorem are given. The explicit equilibrium distribution
function is obtained. The similarities and differences to previous approaches
are discussed. Our results confirm the richness of the Bloch-Peierls-Berry
dynamics
Intravitreal Aflibercept Outcomes in Patients with Persistent Macular Exudate Previously Treated with Bevacizumab and/or Ranibizumab for Neovascular Age-Related Macular Degeneration
Purpose. To assess whether intravitreal aflibercept (2.0mg) can effectively reduce persistent macular exudate and enhance visual acuity in ranibizumab (0.5mg) and/or bevacizumab (1.25 mg) treatment resistant patients with neovascular age-related macular degeneration. Methods. This retrospective study included 47 treatment resistant eyes from 47 patients switched to intravitreal aflibercept injections after receiving a minimum of 3 injections with either ranibizumab or bevacizumab. Snellen visual acuity and optical coherence tomography were assessed just prior to the first injection (baseline) and prior to the fourth injection (final). Additionally, anatomical regions of persistent macular exudate were tracked to determine if these areas yielded varying responses to aflibercept. Results. At baseline, patients had received an average of 11.3 injections with any prior anti-VEGF drug (SD 5.96). For whole group analysis, baseline and final central retinal thickness were 370.57 mu m and 295.7 mu m (P \u3c =.001), respectively. Baseline and final retinal fluid volumes were 4.81 mm(3) and 4.37 mm(3) (P \u3c =.001), respectively. Baseline and final logMAR were 0.56 and 0.53 (P = 0.301), respectively. Anatomic location of persistent exudate did not appreciably alter treatment outcome. Conclusion. Central retinal thickness and total retinal fluid volume were reduced in ranibizumab and/or bevacizumab treatment resistant patients following three aflibercept injections. No appreciable change in visual acuity was noted
Microfocal X-Ray Computed Tomography Post-Processing Operations for Optimizing Reconstruction Volumes of Stented Arteries During 3D Computational Fluid Dynamics Modeling
Restenosis caused by neointimal hyperplasia (NH) remains an important clinical problem after stent implantation. Restenosis varies with stent geometry, and idealized computational fluid dynamics (CFD) models have indicated that geometric properties of the implanted stent may differentially influence NH. However, 3D studies capturing the in vivo flow domain within stented vessels have not been conducted at a resolution sufficient to detect subtle alterations in vascular geometry caused by the stent and the subsequent temporal development of NH. We present the details and limitations of a series of post-processing operations used in conjunction with microfocal X-ray CT imaging and reconstruction to generate geometrically accurate flow domains within the localized region of a stent several weeks after implantation. Microfocal X-ray CT reconstruction volumes were subjected to an automated program to perform arterial thresholding, spatial orientation, and surface smoothing of stented and unstented rabbit iliac arteries several weeks after antegrade implantation. A transfer function was obtained for the current post-processing methodology containing reconstructed 16 mm stents implanted into rabbit iliac arteries for up to 21 days after implantation and resolved at circumferential and axial resolutions of 32 and 50 ÎĽm, respectively. The results indicate that the techniques presented are sufficient to resolve distributions of WSS with 80% accuracy in segments containing 16 surface perturbations over a 16 mm stented region. These methods will be used to test the hypothesis that reductions in normalized wall shear stress (WSS) and increases in the spatial disparity of WSS immediately after stent implantation may spatially correlate with the temporal development of NH within the stented region
Presynchronizing PGF2α and GnRH injections before timed artificial insemination CO-Synch + CIDR program
Fixed-time artificial insemination is an effective management tool that reduces the
labor associated with more conventional artificial insemination programs requiring
detection of estrus. The 7-day CO-Synch + controlled internal drug release (CIDR)
insert protocol has been shown to effectively initiate estrus and ovulation in cycling
and non-cycling suckled beef cows, producing pregnancy rates at or greater than 50%
in beef cows. The gonadotropin-releasing hormone (GnRH) injection that begins the
CO-Synch + CIDR program initiates ovulation in a large proportion of cows, particularly
anestrous cows. The CIDR, which releases progesterone intravaginally, prevents
short estrous cycles that usually follow the first postpartum ovulation in beef cows. Our
hypothesis was that inducing estrus with a prostaglandin injection followed 3 days later
with a GnRH injection, 7 days before applying the 7-day CO-Synch + CIDR protocol,
might increase the percentage of cycling cows that would exhibit synchronous follicular
waves after the onset of the CO-Synch + CIDR protocol. We also hypothesized that
the additional GnRH injection would increase the percentage of anestrous cows that
would ovulate, thereby increasing pregnancy outcomes
Effects of corn steep liquor supplementation on intake and digestion of tallgrass prairie hay contaminated with sericea lespedeza
Sericea lespedeza (Lespedeza cuneata) is a noxious weed that infests approximately 600,000 acres of native range in Kansas. Intake of sericea lespedeza by grazing beef cattle is poor due to the presence of condensed tannins in the plant. Condensed tannins reduce protein digestion by beef cattle and may also decrease plant palatability because of their astringent nature. Prolific seed production, in combination with little or no grazing pressure, has contributed to the rapid spread of sericea lespedeza in the Flint Hills. Increasing grazing pressure on sericea lespedeza may reduce seed production and slow its advance; however, the presence of condensed tannins inhibit consumption by grazing animals. Reports have indicated that feed-grade polyethylene glycol may inhibit formation of tannin-protein complexes in the rumen, but beef producers have not widely adopted polyethylene glycol because, at the rates necessary to increase intake of sericea lespedeza, it is cost-prohibitive and disallowed by regulations. Therefore, identifying substances that are generally regarded as safe (GRAS) by the U.S. Food and Drug Administration, cost-effective, and that mitigate the consequences of consuming a diet high in tannins is advantageous. Such information could lead to a degree of biological control of this noxious weed using the most economically important grazer (i.e., beef cattle) in the Flint Hills. Preliminary research in our laboratory indicated that corn steep liquor has binding affinity for condensed tannins that is similar to polyethylene glycol. Therefore, the objective of our study was to determine the effects of corn steep liquor supplementation on intake and digestion of tallgrass prairie hay contaminated by sericea lespedeza
Preclinical Analysis of JAA-F11, a Specific Anti-Thomsen-Friedenreich Antibody via Immunohistochemistry and In Vivo Imaging.
The tumor specificity of JAA-F11, a novel monoclonal antibody specific for the Thomsen-Friedenreich cancer antigen (TF-Ag-alpha linked), has been comprehensively studied by in vitro immunohistochemical (IHC) staining of human tumor and normal tissue microarrays and in vivo biodistribution and imaging by micro-positron emission tomography imaging in breast and lung tumor models in mice. The IHC analysis detailed herein is the comprehensive biological analysis of the tumor specificity of JAA-F11 antibody performed as JAA-F11 is progressing towards preclinical safety testing and clinical trials. Wide tumor reactivity of JAA-F11, relative to the matched mouse IgG3 (control), was observed in 85% of 1269 cases of breast, lung, prostate, colon, bladder, and ovarian cancer. Staining on tissues from breast cancer cases was similar regardless of hormonal or Her2 status, and this is particularly important in finding a target on the currently untargetable triple-negative breast cancer subtype. Humanization of JAA-F11 was recently carried out as explained in a companion paper "Humanization of JAA-F11, a Highly Specific Anti-Thomsen-Friedenreich Pancarcinoma Antibody and In Vitro Efficacy Analysis" (Neoplasia 19: 716-733, 2017), and it was confirmed that humanization did not affect chemical specificity. IHC studies with humanized JAA-F11 showed similar binding to human breast tumor tissues. In vivo imaging and biodistribution studies in a mouse syngeneic breast cancer model and in a mouse-human xenograft lung cancer model with humanized 124I- JAA-F11 construct confirmed in vitro tumor reactivity and specificity. In conclusion, the tumor reactivity of JAA-F11 supports the continued development of JAA-F11 as a targeted cancer therapeutic for multiple cancers, including those with unmet need
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