Bargmann-Michel-Telegdi equation and one-particle relativistic approach

A reexamination of the semiclassical approach of the relativistic electron indicates a possible variation of its helicity for electric and magnetic static fields applied along its global motion due to zitterbewegung effects, proportional to the anomalous part of the magnetic moment.Comment: 10 pages, LATEX2E, uses amsb

Localization-delocalization transition of a reaction-diffusion front near a semipermeable wall

The A+B --> C reaction-diffusion process is studied in a system where the reagents are separated by a semipermeable wall. We use reaction-diffusion equations to describe the process and to derive a scaling description for the long-time behavior of the reaction front. Furthermore, we show that a critical localization-delocalization transition takes place as a control parameter which depends on the initial densities and on the diffusion constants is varied. The transition is between a reaction front of finite width that is localized at the wall and a front which is detached and moves away from the wall. At the critical point, the reaction front remains at the wall but its width diverges with time [as t^(1/6) in mean-field approximation].Comment: 7 pages, PS fil

Investigating the Contribution of Mature Collagen Crosslinks to Cooked Meat Toughness Using a Stewed Beef Shank Model

Objective: The objective of this study was to investigate mature collagen crosslink densities and their relationship to connective tissue texture using a stewed beef shank model. Study Description: Connective tissue texture, Warner-Bratzler shear force, and collagen content and characteristics were measured for six different beef shank cuts from eight U.S. Department of Agriculture Low Choice beef carcasses (n = 48). Results: Deep digital flexor from the foreshank had the toughest connective tissue texture, greatest Warner-Bratzler shear force value, most cooked collagen content, one of the greatest insoluble collagen percentages, as well as greatest raw and cooked pyridinoline densities among all the beef shank cuts (P \u3c 0.05). Correlation analysis showed that cooked collagen content, percent insoluble collagen, as well as raw pyridinoline densities had positive correlations with connective tissue texture (r = 0.550, 0.498, and 0.560, respectively; P \u3c 0.01) and Warner-Bratzler shear force (r = 0.615, 0.392 and 0.730, respectively; P \u3c 0.05). The Bottom Line: Pyridinoline is a heat stable collagen crosslink that is difficult to degrade even with extensive heat treatment. As a result, raw pyridinoline density is a good indicator for heat insoluble collagen content, cooked beef connective tissue texture, and ultimately, tenderness in beef cuts with high concentration of connective tissue prepared with moist heat cookery

Tafonomía actualística en el Parque Nacional Bosques Petrificados de Jaramillo, Santa Cruz

El presente trabajo forma parte del programa de estudios actualísticos que estamos desarrollando en el marco de nuestras investigaciones arqueológicas en el NE del Macizo del Deseado (Santa Cruz, Argentina). Tiene por objetivo identificar los distintos agentes y procesos tafonómicos que actúan modificando los restos óseos depositados en las distintas unidades geomorfológicas del Parque Nacional Bosques Petrificados de Jaramillo (PNBPJ), para evaluar cuáles de estos microambientes ofrecen condiciones extremas de preservación (buenas vs. malas). Para alcanzar el objetivo llevamos adelante el relevamiento sistemático por transectas de restos de vertebrados modernos distribuidos en distintas unidades geomorfológicas, previamente definidas. Las tendencias obtenidas se discuten con aquellas generadas a partir de la misma metodología en los sectores de Los Toldos, La Huella y Laguna Sierras Blancas, ubicados al noroccidente del PNBPJ. Los resultados indican que en el PNBPJ las mesetas altas son la unidad geomorfológica donde hay menos preservación del registro óseo y que las mesetas intermedias corresponden a las unidades donde existen más posibilidades de localización de contextos en estratigrafía a cielo abierto. Las observaciones realizadas, coinciden con las realizadas previamente en el sector norte del macizo acerca del potencial destructivo de las mesetas altas, y aportan al conocimiento de los procesos de preservación y destrucción del registro óseo que operan en los distintos microambientes del sector. Los resultados obtenidos son de utilidad para el avance de las investigaciones arqueológicas en el área de estudio

Supergravity based inflation models: a review

In this review, we discuss inflation models based on supergravity. After explaining the difficulties in realizing inflation in the context of supergravity, we show how to evade such difficulties. Depending on types of inflation, we give concrete examples, particularly paying attention to chaotic inflation because the ongoing experiments like Planck might detect the tensor perturbations in near future. We also discuss inflation models in Jordan frame supergravity, motivated by Higgs inflation.Comment: 30 pages, invited review for Classical and Quantum Gravity, published versio

Native Beef Collagenase MMP-9 May Contribute to Tenderness Improvement by Degrading Connective Tissues in Extended Aged Beef

Objective: Collagen is one of the main components in the connective tissue (CT) and contributes to background toughness in beef. It is known that in living animals, collagen can be degraded and remodeled by collagenase matrix metalloproteinases (MMP); however, it is unclear if collagenase MMP can impact CT texture during postmortem aging of beef. Therefore, this study aimed to understand how collagenase MMP activity may impact postmortem connective tissue degradation in beef in three different cuts and four different aging periods. Study Description: Beef boneless striploin, top sirloin butt, and heel were acquired from 10 U.S. Department of Agriculture high choice beef carcasses and assigned to be aged for 3, 21, 42, or 63 days (n = 120). Following each aging time, Warner-Bratzler shear force (WBSF), connective tissue shear force (CTSF), trained panel responses, collagen content, denaturation temperature of connective tissue, collagen crosslinks density, connective tissue degradation product, and native collagenase activity were measured, and collagenase identity was identified as MMP-9 through Western blot. Results: Striploin was considered the most tender muscle (P \u3c 0.01), and tenderness was improved (P \u3c 0.01) after 21 days of aging. In addition, CTSF data and trained panelists demonstrated softening (P \u3c 0.05) of CT after 21 days of aging. Heel and top sirloin butt did not differ (P \u3e 0.10) in collagen content and had greater (P \u3c 0.01) collagen content than striploin. However, no aging effect was found for collagen content (P \u3e 0.10). Denaturation temperature of CT decreased and collagen crosslinks density increased after 42 days of aging for all cuts evaluated in this study (P \u3c 0.01). The MMP-9 activity decreased (P \u3c 0.01) from 3 to 21 to 42 days, and it had the greatest (P \u3c 0.01) activity in heel compared to the other two cuts. Heel and striploin had greater (P \u3c 0.01) connective tissue degradation product than top sirloin butt. It was interesting to note that while striploin and heel showed a decrease (P \u3c 0.05) in the degradation product from 3 to 21 to 42 days, top sirloin butt did not show any changes (P \u3e 0.10) in degradation product during the entire 63 days of aging period. The Bottom Line: These results provide an explanation on CT softening during postmortem aging. Understanding the mechanism of tenderness improvement from the softening of CT may help the industry improve the eating quality of lower quality beef cuts

A Preliminary Investigation of the Contribution of Different Tenderness Factors to Beef Loin, Tri-tip, and Heel Tenderness

Objective: The objective is to better understand the contribution of each tenderness factor to the perception of tenderness of three specific beef muscles with similar tenderness ratings. Study Description: Longissimus lumborum (loin), tensor fascia latae (tri-tip), and gastrocnemius (heel) were collected from 10 U.S. Department of Agriculture low Choice beef carcasses and assigned to a 5- or 21-day aging period (n = 60). Steaks from each aging period from each subprimal were assigned to one of three assays: 1) trained sensory analysis; 2) objective tenderness evaluation (Warner-Bratzler shear force); or 3) physiochemical analysis (sarcomere length, proteolysis, intramuscular fat content, collagen crosslink, and content). Results: Sarcomere length, troponin-T degradation, collagen content, mature collagen crosslink density, intramuscular lipid content, and trained panel analysis were measured. Correlation analysis indicated each muscle has a specific tenderness factor that contributed to the overall tenderness evaluated by trained panelists. The equations indicated Longissimus lumborum tenderness was driven by lipid content (P \u3c 0.05) and that Tensor fascia latae tenderness was driven by collagen content (P \u3c 0.05). Gastrocnemius tenderness was driven by proteolysis (P \u3c 0.01), and only collagen content can be casually used as an overall tenderness predictor for all three cuts. The Bottom Line: Each muscle showed a unique tenderness factor profile. Loin is inherently tender, and tri-tip has the makings for a tender cut as seen by our biochemical analysis, yet panelists rated tri-tip to have similar overall tenderness as heel, an inherently tough muscle

An Investigation on the Influence of Various Biochemical Tenderness Factors on Eight Different Bovine Muscles

Objective: Beef tenderness is a complex palatability trait with many tenderness-contributing components. The objective of this study is to understand the relative contribution of each tenderness component to eight different beef muscles. Study Description: Top sirloin butt, ribeye, brisket, flank, knuckle, eye of round, mock tender, and shoulder clod were collected from 10 U.S. Department of Agriculture high choice beef carcasses and assigned to a 2- or 21-day aging period (n = 160). Protein degradation, collagen content, mature collagen crosslink density, intramuscular lipid content, pH, shear force, and trained sensory panel analysis were determined. A Pearson correlation analysis was used to determine the relationship between each tenderness contributor measured in this study to the overall tenderness evaluated by the trained panelist. Results: Overall tenderness of ribeye, flank, eye of round, and shoulder clod were largely driven by the protein degradation of muscle fibers (effect of aging). On the other hand, overall tenderness for brisket was determined by collagen content and crosslink density (effect from connective tissue). Finally, overall tenderness of top sirloin butt was strongly correlated with lipid content. When all the cuts were combined together and analyzed as a whole (n = 160), all of the biochemical measurements conducted in this study played a small but important role as an overall tenderness contributor. The Bottom Line: Results from this study filled in some of the knowledge gap on the relative contribution of each tenderness component to the overall perception of tenderness from each cut. The industry can utilize this information to provide tenderness management strategies for each cut as well as improve the robustness of current tenderness predicting technology

Absolute luminosity measurements with the LHCb detector at the LHC

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic "van der Meer scan" method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented.Comment: 48 pages, 19 figures. Results unchanged, improved clarity of Table 6, 9 and 10 and corresponding explanation in the tex