Controlling the electronic structure of bilayer graphene

We describe the synthesis of bilayer graphene thin films deposited on insulating silicon carbide and report the characterization of their electronic band structure using angle-resolved photoemission. By selectively adjusting the carrier concentration in each layer, changes in the Coulomb potential led to control of the gap between valence and conduction bands. This control over the band structure suggests the potential application of bilayer graphene to switching functions in atomic-scale electronic devices.     

Imaging the Mott insulator shells by using atomic clock shifts

Microwave spectroscopy was used to probe the superfluid-Mott insulator transition of a Bose-Einstein condensate in a three-dimensional optical lattice. By using density-dependent transition frequency shifts, we were able to spectroscopically distinguish sites with different occupation numbers and to directly image sites with occupation numbers from one to five, revealing the shell structure of the Mott insulator phase. We used this spectroscopy to determine the onsite interaction and lifetime for individual shells.     

Influence of early re-spacing on Sitka spruce branch structure

• Context   

The frequency, size, and insertion angle of primary branches are important determinants of wood quality and can be significantly influenced by silvicultural activities.     

Functional connectivity of lynx at their southern range periphery in Ontario,Canada

Peripheral populations are often small and isolated compared to those in the range core, in part due to the patchy distribution of suitable habitats at range margins. It follows that peripheral populations typically occur at lower densities and are more susceptible to extinction, but their persistence may be facilitated through connectivity with core areas. Relationships between connectivity and the distribution of animal populations have not yet been fully evaluated, especially for large carnivores having extensive spatial needs and specialized habitat requirements. Using observations of snow tracks, we modeled occurrence of Canada lynx (Lynx canadensis) in relation to landscape characteristics along their southern range periphery in Ontario, Canada; we sought to assess functional connectivity of lynx habitat along the southern margins of the range. As observed in other studies, young coniferous forests had the highest probability of lynx occurrence, likely due to their association with snowshoe hares (Lepus americanus). We used the occurrence model to parameterize a resistance surface and then circuit theory to predict functional connectivity along the southern periphery of lynx distribution. Lynx typically travelled through landscapes with higher connectivity than random paths, implying that lynx habitat requirements in their southern range likely extend beyond habitat composition, and that conservation efforts should seek to preserve metapopulation dynamics through functional connectivity of suitable habitat across larger spatial scales.     

Consequences of calcium interactions with phytate and phytase for poultry and pigs

Despite increasing practical experience and cascades of scientific reports on exogenous microbial phytases, several issues associated with their use remain unresolved because of the ambiguous and, at times, conflicting data that has been generated. One possible cause of these inconsistent outcomes is dietary calcium (Ca) levels, which are mainly derived from limestone. Thus the purpose of this review is to examine Ca interactions with dietary phytate and phytases, particularly exogenous, microbial phytases, and their consequences for poultry and pigs. The polyanionic phytate molecule has a tremendous capacity to chelate cations and form insoluble Ca–phytate complexes, which are refractory to phytase activity. Thus Ca–phytate complex formation along the gastrointestinal tract, where one phytate (IP₆) molecule binds up to five Ca atoms, assumes importance and approximately one third of dietary Ca may be bound to phytate in digesta. Consequently, phytate limits the availability of both P and Ca as a result of insoluble Ca–phytate complex formation, the extent of which is driven by gut pH and molar ratios of the two components. It is accepted that Ca–phytate complexes are mainly formed in the small intestine where they have a substantial negative influence on the efficacy of mucosal phytase. However, exogenous phytases are mainly active in more proximal segments of the gut and lower pH levels, so their efficacy should not be influenced by Ca–phytate complexes in the small intestine. There is, however, data to indicate that Ca and phytate interactions occur under acidic conditions with the formation of soluble and insoluble Ca–phytate species, which could negatively impact on exogenous phytase efficacy. Also, Ca will tend to elevate gut pH because of limestone's very high acid binding capacity, which will favour Ca–phytate interactions and may influence the activity of exogenous phytases depending on their pH activity spectrum. The de novo formation of binary protein–phytate complexes that are refractory to pepsin hydrolysis may be fundamental to the negative impact of phytate on the digestibility of protein/amino acids. However, high dietary Ca levels may disrupt protein–phytate complex formation by interacting with both phytate and protein even at acidic pH levels, thereby influencing the outcomes of phytase amino acid digestibility assays. Finally, it is increasingly necessary to define the Ca and nonphytate-P requirements of pigs and poultry offered phytase-supplemented diets.     

Assessment of on-screen measurements, magnification, and calibration in digital radiography

Objective-To compare calibration methods for digital radiography in terms of measurement accuracy and interobserver variability. Design-Prospective study. Sample-Digital radiographic images of a 155-mm-long Steinmann pin. Procedures-Measurement of pin length on digital radiographs was determined with a 25.4-mm-diameter calibration ball and commercially available software program via 3 calibration methods (ie, no calibration, autocalibration, and manual calibration). Digital radiographs of the calibration ball and pin were obtained with each placed at various vertical heights from the table (7 heights) and horizontal distances from the center of the beam (4 distances). Measurements of pin length on digital radiographs were made by 4 observers who were blinded to the orientation of the calibration ball and pin. Results-Pin lengths obtained by each calibration method were significantly different from each other and from the true value. Manual calibration was the most accurate. There was no significant interobserver variability in measurements. There was no significant change in measurements when the calibration ball was moved horizontally, but pin length measurements changed significantly when the ball was moved vertically (away from the table) with an approximate magnification error of 1% per centimeter of distance between the calibration ball and pin. Conclusions and Clinical Relevance-For digital radiography, manual calibration is recommended to achieve the most accurate measurements. Ideally, the calibration ball should be placed at the same vertical height as the object to be measured; however, if this cannot be achieved, the magnification error can be expected to be approximately 1% per centimeter of distance.     

Viral and bacterial diseases in livestock in Mongolia

This review focuses on the status of infectious diseases that are serious for animal health and have adverse economic effects in Mongolia. Data presented here are limited due to the lack of published or other easily available documents. Foot-and-mouth disease continues to cause substantial economic losses as exemplified by the outbreak of infection with serotype O PanAsia lineage virus. In the case of the 2001 outbreak, a 65% reduction in export revenues was recorded. In order to ascertain the free status of Mongolia from rinderpest, sero-epidemiological surveillance has been carried out since 2001. In 2004, Mongolia was certified free from rinderpest by Office International des Epizooties (OIE). A sharp rise in both animal and human brucellosis incidence has become a serious problem. Rabies and anthrax remain endemic with occasional human cases. Other prevailing infectious diseases are contagious pustular dermatitis, contagious agalactia, enterotoxemia and pasteurellosis. The current programs for the control of infectious diseases in livestock in Mongolia lack a definite policy that would enable rapid implementation. A large-scale surveillance of infectious diseases in animals and management of appropriate preventive measures are urgently required in Mongolia.     

Effects of supplementing with calcium salts of palm oil fatty acids or hydrogenated tallow on ewe milk production and twin lamb growth

Two experiments were conducted with Polypay ewes nursing twin lambs to evaluate the effects of supplementing fat (calcium salts of palm oil fatty acids or hydrogenated tallow) on ewe lactation. In Exp. 1, ewes were fed a 52% concentrate:48% hay-based diet (as-fed basis) consisting of alfalfa hay (n = 4), endophyte-free fescue hay (n = 4), or fescue hay with 3.7% fatty acids (n = 4) from d 4 to 56 of lactation. In Exp. 2, ewes were fed similar diets that had endophyte-free fescue hay (n = 6), fescue hay with 3.7% fatty acids (n = 5), or fescue hay with 3.1% tallow (n = 6) from d 14 before lambing until d 57 of lactation. Diet formulations with supplemental fat were more nutrient dense, and treatments were fed to meet ewe nutrient requirements; this caused diets with added fat to be offered at 10 and 17% lower rates than unsupplemented diets in Exp. 1 and 2, respectively. Lambs were maintained to consume only ewe milk. Ewe milk production and composition were determined using a portable milking machine following a 3-h separation from lambs. In Exp. 1, milk fat content was increased (P < 0.01) when ewes consumed fescue hay with fatty acids vs. the fescue hay diet (11.4 vs. 8.3%). Ewes fed fescue hay with fatty acids lost the most (P < 0.05) weight over lactation (-8.6 kg) compared with ewes fed the alfalfa hay (-2.4 kg) and fescue hay (-3.8 kg) diets. Other milk measures, lamb gain, and production efficiencies were not changed. In Exp. 2, ewes supplemented with fatty acids produced more (P < 0.05) milk fat than those fed tallow (290 vs. 210 g/d). The proportion of synthesized milk fat 14:0 was decreased (P < 0.01), but the percentage of incorporated 16:0 increased (P < 0.05) when fatty acids were fed. Dietary fat digestibility by ewes was increased (P < 0.01) by fatty acid supplementation but decreased (P < 0.01) when tallow was added. Although ewe weight measures were not changed in Exp. 2, twin lamb gain per ewe organic matter intake was most efficient (P < 0.05) when ewes were supplemented with fatty acids. Results suggest that feeding hydrogenated tallow decreased nutrient availability for ewe milk fat production. A complete diet based on endophyte-free fescue hay can replace a traditional alfalfa hay diet, whereas supplementing with the calcium salts of palm oil fatty acids may be more feasible when energy is limiting during ewe lactation.     

Intermittent bolus injection versus continuous infusion of furosemide in normal adult greyhound dogs

Several studies in human subjects have demonstrated greater diuresis with constant rate infusion (CRI) furosemide than intermittent bolus (IB) furosemide. This study was conducted to compare the diuretic efficacy of the same total dose of IB furosemide and CRI furosemide in 6 healthy, adult Greyhound dogs in a randomized crossover design with a 2-week washout period between treatments. For IB administration, dogs received 3 mg/kg at 0 and 4 hours. For CRI administration, dogs received a 0.66 mg/kg loading dose followed by 0.66 mg/kg/h over 8 hours. The same volume of fluid was administered for both methods. Urine output was quantified hourly. Urine electrolyte concentrations, urine specific gravity (USG), packed cell volume (PCV), total protein (TP), serum electrolyte concentrations, total carbon dioxide (TCO2), serum creatinine (sCr), and blood urea nitrogen (BUN) were determined every 2 hours. Urine production and water intake were greater (P < or = 0.05) for CRI than IB. Urine sodium and calcium losses were greater (P < 0.05) and urine potassium loss was less (P = 0.03) for CRI than IB, but there was no evidence of a difference between methods for urine magnesium and chloride losses. Serum chloride concentration was less (P < 0.001), sCr concentration greater (P = 0.04). TP greater (P = 0.01), and PCV greater (P = 0.003) for CRI than IB. No differences in USG, TCO2, BUN, or serum potassium, sodium, and magnesium concentrations were detected between methods. The same total dose of CRI furosemide resulted in more diuresis, natriuresis, and calciuresis and less kaliuresis than IB furosemide in these normal Greyhound dogs over 8 hours, suggesting that furosemide is a more effective diuretic when administered by CRI than by IB.