The Influence of Growth Stage on Carcass Compositionand Factors Associated with Marbling Development in Beef Cattle

There are many cellular regulatory factors that ultimately determine the intramuscular fat, or marbling content and quality of beef carcasses. Identifying factors which play a critical role in the development of intramuscular fat throughout the feeding period and determining how cattle feeders can manipulate these factors will be crucial to continue improving beef quality. Ideally, marbling must increase without excess accumulation of adipose in depots that are undesirable and economically detrimental (subcutaneous and visceral). The results of this study are novel as they show not only what cellular factors play a role in marbling development, but also how their expression and presence change as an animal grows in an American‐style production system. The increase in both expression and presence of peroxisome proliferator‐activated receptor γ (PPARγ) at the end of the feeding phase suggest the proliferation and differentiation of additional cells to adipocytes is required in order to increase intramuscular fat content. This does not mean that adipocyte filling (lipogenesis) does not play a key role as well. However marbling content will reach a plateau without the recruitment of additional adipocytes. While it has been previously established that intramuscular adipocytes have a pattern of metabolism unique to other adipocytes, further research into how the metabolism of intramuscular fat differs from other fat depots and how this metabolism changes throughout the feeding phase will enhance the ability to produce high quality carcasses while limiting undesirable carcass fat

The Influence of Caspase-3 on the Calpain Enzyme System During Meat Aging

Tenderness is a key component of palatability, which influences consumers’ perception of meat quality. There are a variety of factors that contribute to variations in tenderness, including postmortem proteolysis. A more complete understanding of this biological mechanism regulating tenderness is needed to ensure consistently tender beef. Numerous reports indicate μ-calpain is primarily responsible for the degradation of proteins postmortem. Additionally, it has been shown that caspase-3 can cleave calpastatin, the inhibitor of μ-calpain. Therefore, the objective of this study was to determine if in vitro degradation of calpastatin by caspase-3 can enhance the postmortem breakdown of myofibrillar proteins by μ-calpain. Bovine semitendinosus muscles were excised from two carcasses 20 min postmortem. Muscle strips were dissected from the semitendinosus, restrained to maintain length, and placed in a neutral buffer containing protease inhibitors. Upon rigor completion, myofibrils were isolated from each strip and sarcomere length was determined. Samples with similar sarcomere lengths were selected to minimize the effect of sarcomere length on proteolysis. Myofibrils were then incubated at 22°C with μ-calpain, μ-calpain + calpastatin, caspase-3 + calpastatin, or μ-calpain + caspase-3 + calpastatin for 0.25, 1, 3, 24, 48, or 72 hr at a pH of 6.8. Proteolysis of troponin T and calpastatin was evaluated using SDS-PAGE and western blotting techniques. Analysis of western blots confirmed significant degradation of calpastatin by caspase-3. Additionally, western blots revealed intact calpastatin disappeared rapidly due to digestion by μ-calpain. While caspase-3 did not significantly degrade troponin T, all μ-calpain digestion treatments resulted in substantial troponin T breakdown. Degradation of troponin T did not differ between the μ-calpain + calpastatin and μ-calpain + caspase-3 + calpastatin digestions. Results of this study indicate caspase-3 cleavage of calpastatin does not enhance in vitro degradation of myofibrillar proteins by μ-calpain

Far-infrared photo-conductivity of electrons in an array of nano-structured antidots

We present far-infrared (FIR) photo-conductivity measurements for a two-dimensional electron gas in an array of nano-structured antidots. We detect, resistively and spectrally resolved, both the magnetoplasmon and the edge-magnetoplasmon modes. Temperature-dependent measurements demonstrates that both modes contribute to the photo resistance by heating the electron gas via resonant absorption of the FIR radiation. Influences of spin effect and phonon bands on the collective excitations in the antidot lattice are observed.Comment: 5 pages, 3 figure

Stability of periodic domain structures in a two-dimensional dipolar model

We investigate the energetic ground states of a model two-phase system with 1/r^3 dipolar interactions in two dimensions. The model exhibits spontaneous formation of two kinds of periodic domain structure. A striped domain structure is stable near half filling, but as the area fraction is changed, a transition to a hexagonal lattice of almost-circular droplets occurs. The stability of the equilibrium striped domain structure against distortions of the boundary is demonstrated, and the importance of hexagonal distortions of the droplets is quantified. The relevance of the theory for physical surface systems with elastic, electrostatic, or magnetostatic 1/r^3 interactions is discussed.Comment: Revtex (preprint style, 19 pages) + 4 postscript figures. A version in two-column article style with embedded figures is available at http://electron.rutgers.edu/~dhv/preprints/index.html#ng_do

Search for Exotic Mesons in pi- P Interactions at 18 GeV/c

The recent search for non $q \bar{q}$ mesons in $\pi^{-}p$ interactions at Brookhaven National Laboratory is summarized. Many final states such as $\eta \pi$, $\eta' \pi^{-}$, $a_{0} \pi$, $f_{1} \pi$, $a_{2} \pi$, $b_{1} \pi$, which are favored decay modes of exotics, are under investigation.Comment: 9 pages, PostScript, Presented at the International School of Nuclear Physics, Erice, Sicily, Italy, September 199

Confirmation of a pi_1^0 Exotic Meson in the \eta \pi^0 System

The exclusive reaction $\pi^- p \to \eta \pi^0 n$, $\eta \to \pi^+ \pi^- \pi^0$ at 18 GeV$/c$ has been studied with a partial wave analysis on a sample of 23~492 $\eta \pi^0 n$ events from BNL experiment E852. A mass-dependent fit is consistent with a resonant hypothesis for the $P_+$ wave, thus providing evidence for a neutral exotic meson with $J^{PC} = 1^{-+}$, a mass of $1257 \pm 20 \pm 25$ MeV$/c^2$, and a width of $354 \pm 64 \pm 60$ MeV$/c^2$. New interpretations of the meson exotics in neutral $\eta \pi^0$ system observed in E852 and Crystal Barrel experiments are discussed.Comment: p3, rewording the paragraph (at the bottom) about the phase variations. p4, rewording paragrath "The second method ..." . p4, at the bottom of paragrath "The third method ..." added consistent with the results of methods 1 and 2

Exotic Meson Production in the f1(1285)π−f_{1}(1285)\pi^{-} System observed in the Reaction π−p→ηπ+π−π−p\pi^{-} p \to \eta\pi^{+}\pi^{-}\pi^{-} p at 18 GeV/c

This letter reports results from the partial wave analysis of the $\pi^{-}\pi^{-}\pi^{+}\eta$ final state in $\pi^{-}p$ collisions at 18GeV/c. Strong evidence is observed for production of two mesons with exotic quantum numbers of spin, parity and charge conjugation, $J^{PC} = 1^{-+}$ in the decay channel $f_{1}(1285)\pi^{-}$. The mass $M = 1709 \pm 24 \pm 41$ MeV/c^2 and width $\Gamma = 403 \pm 80 \pm 115$ MeV/c^2 of the first state are consistent with the parameters of the previously observed $\pi_{1}(1600)$. The second resonance with mass $M = 2001 \pm 30 \pm 92$ MeV/c^2 and width $\Gamma = 333 \pm 52 \pm 49$ MeV/c^2 agrees very well with predictions from theoretical models. In addition, the presence of $\pi_{2}(1900)$ is confirmed with mass $M = 2003 \pm 88 \pm 148$ MeV/c^2 and width $\Gamma = 306 \pm 132 \pm 121$ MeV/c^2 and a new state, $a_{1}(2096)$, is observed with mass $M = 2096 \pm 17 \pm 121$ MeV/c^2 and width $\Gamma = 451 \pm 41 \pm 81$ MeV/c^2. The decay properties of these last two states are consistent with flux tube model predictions for hybrid mesons with non-exotic quantum numbers

Observation of a New J(PC)=1(+-) Isoscalar State in the Reaction Pi- Proton -> Omega Eta Neutron at 18 GeV/c

Results are presented on a partial wave analysis of the Omega Eta final state produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0 -> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=384(60)(+70)(-100) MeV/c^2. The h1(1595) state exhibits resonant-like phase motion relative to the Omega(1650).Comment: Submitted to Physics Letters B Eight total pages including 11 figures and 1 tabl

An FPTAS for optimizing a class of low-rank functions over a polytope

We present a fully polynomial time approximation scheme (FPTAS) for optimizing a very general class of non-linear functions of low rank over a polytope. Our approximation scheme relies on constructing an approximate Pareto-optimal front of the linear functions which constitute the given low-rank function. In contrast to existing results in the literature, our approximation scheme does not require the assumption of quasi-concavity on the objective function. For the special case of quasi-concave function minimization, we give an alternative FPTAS, which always returns a solution which is an extreme point of the polytope. Our technique can also be used to obtain an FPTAS for combinatorial optimization problems with non-linear objective functions, for example when the objective is a product of a fixed number of linear functions. We also show that it is not possible to approximate the minimum of a general concave function over the unit hypercube to within any factor, unless P = NP. We prove this by showing a similar hardness of approximation result for supermodular function minimization, a result that may be of independent interest

Observation of Pseudoscalar and Axial Vector Resonances in pi- p -> K+ K- pi0 n at 18 GeV

A new measurement of the reaction pi- p -> K+ K- pi0 n has been made at a beam energy of 18 GeV. A partial wave analysis of the K+ K- pi0 system shows evidence for three pseudoscalar resonances, eta(1295), eta(1416), and eta(1485), as well as two axial vectors, f1(1285), and f1(1420). Their observed masses, widths and decay properties are reported. No signal was observed for C(1480), an IG J{PC} = 1+ 1{--} state previously reported in phi pi0 decay.Comment: 7 pages, 6 figs, to be submitted to Phys. Let