Magneto-optical characterization of MnxGe1-x alloys obtained by ion implantation

Magneto-optical Kerr effect hysteresis loops at various wavelengths in the visible/near-infrared range have been used to characterize the magnetic properties of alloys obtained by implanting Mn ions at fixed energy in a Ge matrix. The details of the hysteresis loops reveal the presence of multiple magnetic contributions. They may be attributed to the inhomogeneous distribution of the magnetic atoms and, in particular, to the known coexistence of diluted Mn in the Ge matrix and metallic Mn-rich nanoparticles embedded in it [Phys. Rev. B 73, 195207(2006)].Comment: 2 pages, 2 figures. Proceeding of the International Conference on Magnetism. Kyoto, August 20-25 200

Primary Care Based Population Health in a Community Health System: Evaluation of Strategies, Lessons Learned and Key Results

Theory: As value-based programs continue to proliferate, healthcare delivery providers must adapt accordingly to meet these new demands. This study examines the strategies, lessons learned, and key results of the Greater Baltimore Health Alliance (GBHA), a patient-centered medical home (PCMH) community healthcare provider, in the population health context. Methods: This study follows the work-place challenge format and as such includes an organizational assessment, plan for new service, program evaluation, economic evaluation, and discussion of implications. The organizational assessment leverages survey tools to study GBHA staff and leaders using the Baldrige Excellence Framework. The plan for new services outlines a plan and early results for integrated behavioral health in the PCMH setting. The program evaluation includes a run chart analysis, bivariate analysis, and logistic regression analysis to study colorectal cancer screening compliance rates at GBHA. The economic evaluation methods include a cost consequence analysis and return on investment analysis for GBHA. The implications section leverages a literature review and general discussion. Results: The organizational assessment of GBHA revealed strengths in leadership, strategy, workforce and operations. The organizational assessment also indicated that GBHA has opportunity for improvement in the areas of customers, measurement, analysis and knowledge management, and results. The plan for new service revealed a nearly completed implementation of integrated behavioral health and early results indicate further opportunity for outcome measure refinement, workflow standardization, policy and procedure development, and the establishment of goal thresholds. The program evaluation indicated special cause variation in the run chart as well as increased odds of screening for patients seen in practices with greater length of time recognized as a PCMH. The economic evaluation indicated significant investment in GBHA, largely positive quality outcomes, and progressively increasing return on investment each fiscal year. The discussion of implications underlined the importance of GBHA to stay abreast of federal regulations, which may dictate strategy changes. Conclusions: GBHA has been largely successful in meeting the evolving demands of the population health landscape. GBHA’s location in Maryland provides additional financial incentive to make investment in PCMH strategies more feasible. Additional study is necessary as the behavioral health integration implementation continues

A model for the onset of transport in systems with distributed thresholds for conduction

We present a model supported by simulation to explain the effect of temperature on the conduction threshold in disordered systems. Arrays with randomly distributed local thresholds for conduction occur in systems ranging from superconductors to metal nanocrystal arrays. Thermal fluctuations provide the energy to overcome some of the local thresholds, effectively erasing them as far as the global conduction threshold for the array is concerned. We augment this thermal energy reasoning with percolation theory to predict the temperature at which the global threshold reaches zero. We also study the effect of capacitive nearest-neighbor interactions on the effective charging energy. Finally, we present results from Monte Carlo simulations that find the lowest-cost path across an array as a function of temperature. The main result of the paper is the linear decrease of conduction threshold with increasing temperature: $V_t(T) = V_t(0) (1 - 4.8 k_BT P(0)/ p_c)$, where $1/P(0)$ is an effective charging energy that depends on the particle radius and interparticle distance, and $p_c$ is the percolation threshold of the underlying lattice. The predictions of this theory compare well to experiments in one- and two-dimensional systems.Comment: 14 pages, 10 figures, submitted to PR

Hydrogen induced optically-active defects in silicon photonic nanocavities

This work was supported by Era-NET NanoSci LECSIN project coordinated by F. Priolo, by the Italian Ministry of University and Research, FIRB contract No. RBAP06L4S5 and by the EPSRC UKSp project. Partial financial support by the Norwegian Research Council is also acknowledged.We demonstrate intense room temperature photoluminescence (PL) from optically active hydrogen- related defects incorporated into crystalline silicon. Hydrogen was incorporated into the device layer of a silicon on insulator (SOI) wafer by two methods: hydrogen plasma treatment and ion implantation. The room temperature PL spectra show two broad PL bands centered at 1300 and 1500 nm wavelengths: the first one relates to implanted defects while the other band mainly relates to the plasma treatment. Structural characterization reveals the presence of nanometric platelets and bubbles and we attribute different features of the emission spectrum to the presence of these different kind of defects. The emission is further enhanced by introducing defects into photonic crystal (PhC) nanocavities. Transmission electron microscopy analyses revealed that the isotropicity of plasma treatment causes the formation of a higher defects density around the whole cavity compared to the ion implantation technique, while ion implantation creates a lower density of defects embedded in the Si layer, resulting in a higher PL enhancement. These results further increase the understanding of the nature of optically active hydrogen defects and their relation with the observed photoluminescence, which will ultimately lead to the development of intense and tunable crystalline silicon light sources at room temperature.Publisher PDFPeer reviewe

Fatty acid profile in the ruminal fluid and in the m. longissimus dorsi of lambs fed herbage or concentrate with or without tannins

Twenty-eight male lambs were divided into two groups at age 45 d. Fourteen lambs were given fresh herbage (vetch); the remaining lambs were fed a concentrate-based diet. Within each treatment, seven lambs received a supplementation of quebracho tannins. At slaughter (age 105 d) the ruminal content and the muscle longissimus dorsi (LD) were collected. Ruminal fluid and LD fatty acid composition was determined by gas chromatography. Among the concentrates-fed lambs, tannins supplementation reduced (P < 0.05) the concentration of C18:0 (- 49 %) and increased vaccenic acid (VA; + 69 %) in the ruminal fluid. When tannins were included into the concentrate, the LD contained double levels of rumenic acid (RA) as compared to the LD of the lambs fed the tannins-free concentrate (0.96 vs. 0.46 % of total extracted fatty acids, respectively; P < 0.05). The concentration of PUFA was higher (P < 0.05) and SFA (P < 0.01) lower in the LD from lambs fed the tannin diets as compared to the animals receiving the tannin-free diets. In conclusion, tannins reduce the biohydrogenation of the PUFA in the rumen. This implies that tannins supplementation could be a strategy to increase the RA and PUFA content and to reduce the SFA into ruminant meats

Experimental quantification of useful and parasitic absorption of light in plasmon-enhanced thin silicon films for solar cells application

A combination of photocurrent and photothermal spectroscopic techniques is applied to experimentally quantify the useful and parasitic absorption of light in thin hydrogenated microcrystalline silicon (μc-Si:H) films incorporating optimized metal nanoparticle arrays, located at the rear surface, for improved light trapping via resonant plasmonic scattering. The photothermal technique accounts for the total absorptance and the photocurrent signal accounts only for the photons absorbed in the μc-Si:H layer (useful absorptance); therefore, the method allows for independent quantification of the useful and parasitic absorptance of the plasmonic (or any other) light trapping structure. We demonstrate that with a 0.9 μm thick absorber layer the optical losses related to the plasmonic light trapping in the whole structure are insignificant below 730 nm, above which they increase rapidly with increasing illumination wavelength. An average useful absorption of 43% and an average parasitic absorption of 19% over 400-1100 nm wavelength range is measured for μc-Si:H films deposited on optimized self-assembled Ag nanoparticles coupled with a flat mirror (plasmonic back reflector). For this sample, we demonstrate a significant broadband enhancement of the useful absorption resulting in the achievement of 91% of the maximum theoretical Lambertian limit of absorption

Lamb meat colour stability as affected by dietary tannins

Twenty-one male Comisana lambs were divided into three groups at 45 days of age and were individually penned for 60 days. Seven lambs were fed a concentrate-based diet (C), seven lambs received the same concentrate with the addiction of tannins from quebracho (Schinopsis lorentzii; T), whereas the remaining animals were fed exclusively fresh vetch (Vicia sativa; H). Colour descriptors (a*, b* and H*) and metmyoglobin (MMb) percentages were measured on minced semimembranosus muscle over 14 days of refrigerated storage in a high oxygen atmosphere. Regardless of dietary treatment, meat redness decreased, while yellowness and hue angle increased (P < 0.001) over storage duration. However, higher a* values, lower b* values and lower H* values were observed in meat from both H- and T-fed animals as compared to meat from C-fed lambs (P = 0.012; P = 0.02; P = 0.003, respectively). Metmyoglobin formation increased over time (P < 0.001), but H diet resulted in lower metmyoglobin percentages than C diet (P = 0.007). We conclude that the inclusion of tannins into the concentrate improved meat colour stability compared to a tannin-free concentrate. Moreover, the protective effect of tannins against meat discolouration was comparable to that obtained by feeding lambs fresh herbage

Study of phytoproteases stability in aqueous-organic biphasic systems using linear free energy relationships

In this paper we study the effect of different water-immiscible organic solvents (benzene, toluene, 1-butanol, 1-octanol, dichloroethane, dichloromethane, diethyl ether, hexane, chlorobenzene, acetophenone, n-dodecane, trichloroethylene, ethyl acetate) on the stability (residual caseinolytic activity after 4 h) of soluble phytoproteases, such as araujiain, funastrain and papain in aqueous-organic biphasic systems. Besides, the effect of organic solvents on enzymatic catalysis was quantitatively studied by means of linear free energy relationships (LFERs). The organic solvents were characterized by several physicochemical properties, and multiple linear regression analysis (MLRA) together with non-linear regression were the methods used to search the relationships between the residual caseinolytic activity data and several physicochemical parameters. Those enzymes show much greater activity and stability in some biphasic media than in water. On the other hand, all developed correlations represented highly significant LFERs models and showed that non-specific polar and hydrophobic factors are of prime and approximately equal importance for the biocatalytic activity of araujiain, funastrain and papain in the studied biphasic systems, while the specific polar interactions are of little importance for activity. The results suggested that araujiain, funastrain and papain do not suffer unfolding in the studied biphasic media and they are able to retain their native or native-like configurations, though with altered characteristics or properties. This fact was demonstrated by means of a comparative FTIR spectroscopy study in both, buffer and biphasic media, for each studied enzyme.Facultad de Ciencias Exacta