Stable Cliff Climbing For Hexapod Robot With Articulated Body

The paper describes kinematic control for hexapod robot with three{segment articulated body. Forward and inverse kinematics for articulated body de- scribed. Static stability studied in case of climbing the so{called cli obstacle. Conditions for static stability during climbing sequence provided

A Multi-Epoch HST Study of the Herbig-Haro Flow from XZ Tauri

We present nine epochs of Hubble Space Telescope optical imaging of the bipolar outflow from the pre-main sequence binary XZ Tauri. Our data monitors the system from 1995-2005 and includes emission line images of the flow. The northern lobe appears to be a succession of bubbles, the outermost of which expanded ballistically from 1995-1999 but in 2000 began to deform and decelerate along its forward edge. It reached an extent of 6" from the binary in 2005. A larger and fainter southern counterbubble was detected for the first time in deep ACS images from 2004. Traces of shocked emission are seen as far as 20" south of the binary. The bubble emission nebulosity has a low excitation overall, as traced by the [S II]/H-alpha line ratio, requiring a nearly comoving surrounding medium that has been accelerated by previous ejections or stellar winds. Within the broad bubbles there are compact emission knots whose alignments and proper motions indicate that collimated jets are ejected from each binary component. The jet from the southern component, XZ Tau A, is aligned with the outflow axis of the bubbles and has tangential knot velocities of 70-200 km/s. Knots in the northern flow are seen to slow and brighten as they approach the forward edge of the outermost bubble. The knots in the jet from the other star, XZ Tau B, have lower velocities of ~100 km/s

The Catalytic Machinery of a Key Enzyme in Amino Acid Biosynthesis

The aspartate pathway of amino acid biosynthesis is essential for all microbial life but is absent in mammals. Characterizing the enzyme-catalyzed reactions in this pathway can identify new protein targets for the development of antibiotics with unique modes of action. The enzyme aspartate β-semialdehyde dehydrogenase (ASADH) catalyzes an early branch point reaction in the aspartate pathway. Kinetic, mutagenic, and structural studies of ASADH from various microbial species have been used to elucidate mechanistic details and to identify essential amino acids involved in substrate binding, catalysis, and enzyme regulation. Important structural and functional differences have been found between ASADHs isolated from these bacterial and fungal organisms, opening the possibility for developing species-specific antimicrobial agents that target this family of enzymes

Towards a resource-based habitat approach for spatial modelling of vector-borne disease risks

Given the veterinary and public health impact of vector-borne diseases, there is a clear need to assess the suitability of landscapes for the emergence and spread of these diseases. Current approaches for predicting disease risks neglect key features of the landscape as components of the functional habitat of vectors or hosts, and hence of the pathogen. Empirical–statistical methods do not explicitly incorporate biological mechanisms, whereas current mechanistic models are rarely spatially explicit; both methods ignore the way animals use the landscape (i.e. movement ecology). We argue that applying a functional concept for habitat, i.e. the resource-based habitat concept (RBHC), can solve these issues. The RBHC offers a framework to identify systematically the different ecological resources that are necessary for the completion of the transmission cycle and to relate these resources to (combinations of) landscape features and other environmental factors. The potential of the RBHC as a framework for identifying suitable habitats for vector-borne pathogens is explored and illustrated with the case of bluetongue virus, a midge-transmitted virus affecting ruminants. The concept facilitates the study of functional habitats of the interacting species (vectors as well as hosts) and provides new insight into spatial and temporal variation in transmission opportunities and exposure that ultimately determine disease risks. It may help to identify knowledge gaps and control options arising from changes in the spatial configuration of key resources across the landscape. The RBHC framework may act as a bridge between existing mechanistic and statistical modelling approaches

Characterization of a Reverse-Phase Perfluorocarbon Emulsion for the Pulmonary Delivery of Tobramycin

Background: Aerosolized delivery of antibiotics is hindered by poor penetration within distal and plugged airways. Antibacterial perfluorocarbon ventilation (APV) is a proposed solution in which the lungs are partially or totally filled with perfluorocarbon (PFC) containing emulsified antibiotics. The purpose of this study was to evaluate emulsion stability and rheological, antibacterial, and pharmacokinetic characteristics. Methods: This study examined emulsion aqueous droplet diameter and number density over 24?hr and emulsion and neat PFC viscosity and surface tension. Additionally, Pseudomonas aeruginosa biofilm growth was measured after 2-hr exposure to emulsion with variable aqueous volume percentages (0.25, 1, and 2.5%) and aqueous tobramycin concentrations (Ca=0.4, 4, and 40?mg/mL). Lastly, the time course of serum and pulmonary tobramycin concentrations was evaluated following APV and conventional aerosolized delivery of tobramycin in rats. Results: The initial aqueous droplet diameter averaged 1.9±0.2??m with little change over time. Initial aqueous droplet number density averaged 3.5±1.7?109 droplets/mL with a significant (p<0.01) decrease over time. Emulsion and PFC viscosity were not significantly different, averaging 1.22±0.03?10?3 Pa·sec. The surface tensions of PFC and emulsion were 15.0±0.1?10?3 and 14.6±0.6?10?3 N/m, respectively, and the aqueous interfacial tensions were 46.7±0.3?10?3 and 26.9±11.0?10?3 N/m (p<0.01), respectively. Biofilm growth decreased markedly with increasing Ca and, to a lesser extent, aqueous volume percentage. Tobramycin delivered via APV yielded 2.5 and 10 times larger pulmonary concentrations at 1 and 4?hr post delivery, respectively, and significantly (p<0.05) lower serum concentrations compared with aerosolized delivery. Conclusions: The emulsion is bactericidal, retains the rheology necessary for pulmonary delivery, is sufficiently stable for this application, and results in increased pulmonary retention of the antibiotic.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140105/1/jamp.2013.1058.pd

Ancient stars beyond the Local Group: RR Lyrae variables and Blue Horizontal Branch stars in Sculptor Group Dwarf Galaxies

We have used Hubble Space Telescope ACS images to generate color-magnitude diagrams that reach below the magnitude of the horizontal branch in the Sculptor Group dwarf galaxies ESO294-010 and ESO410-005. In both diagrams blue horizontal branch stars are unambiguously present, a signature of the existence of an ancient stellar population whose age is comparable to that of the Galactic halo globular clusters. The result is reinforced by the discovery of numerous RR Lyrae variables in both galaxies. The occurrence of these stars in the first direct confirmation of the existence of ancient stellar populations beyond the Local Group and indicates that star formation can occur at the earliest epochs even in low density environments.Comment: 11 pages, 2 figures, accepted for publication in Astrophysical Journal Letter

The magnetic field and geometry of the oblique shock in the jet of 3C 346

We investigate the brightest regions of the kpc-scale jet in the powerful radio galaxy 3C 346, using new optical HST ACS/F606W polarimetry together with Chandra X-ray data and 14.9 GHz and 22.5 GHz VLA radio polarimetry. The jet shows a close correspondence in optical and radio morphology, while the X-ray emission shows an 0.80 +/- 0.17 kpc offset from the optical and radio peak positions. Optical and radio polarimetry show the same apparent magnetic field position angle and fractional polarization at the brightest knot, where the jet undergoes a large kink of almost 70 degrees in the optical and radio images. The apparent field direction here is well-aligned with the new jet direction, as predicted by earlier work that suggested the kink was the result of an oblique shock. We have explored models of the polarization from oblique shocks to understand the geometry of the 3C 346 jet, and find that the upstream flow is likely to be highly relativistic (0.91 +0.05 / -0.07 c), where the plane of the shock front is inclined at an angle of 51 (+/- 11) degrees to the upstream flow which is at an angle 14 (+8 / -7) degrees to our line of sight. The actual deflection angle of the jet in this case is only 22 degrees.Comment: 11 pages, 5 figures. Accepted by MNRA

Нахождение областей сходимости и вычисление сумм степенных рядов от h-комплексного переменного

Herein, taking power series from a real variable that converge on a certain interval to known sums, the authors consider the power series with the same coefficients from an h-complex variable. For such series, the interiors of the regions of convergence are found, and their sums are explicitly expressed in terms of the sums of the original series. Along the way, the problem of isolation conditions for the zeros of the sums of such series is solved.Взяв степенные ряды от вещественного переменного, сходящиеся на некотором интервале к известным суммам, авторы рассматривают степенные ряды с теми же коэффициентами от h-комплексного переменного. Для таких рядов найдены внутренности областей сходимости, а их суммы явно выражены через суммы исходных рядов. Попутно решен вопрос об условиях изолированности нулей сумм таких рядов