The crystal growth and properties op some chalcogenides of zinc and cadmium

The main purpose of the work described in this thesis was to develop techniques for producing boules of ZnSe and ZnS(_x)Se(_1-x) suitable for research purposes. This was accomplished by extending the method that Clark and Woods((^1)) used for CdS to the higher temperatures needed to grow ZnS and ZnS(_x)Se(_1-x) in the range x = 0-0.6. In this system the capsule is connected to a reservoir of one of the components via a narrow orifice to maintain constant growth conditions. The system has been examined theoretically in an attempt to learn more about the actual conditions of growth within the capsule. It was concluded that growth occurs close to stoichiometry with(the ratio of P(_se2)/P(_zn) at the growth face) approximately 0.194 or 1.12 according to the element in the reservoir. Particular emphasis was placed upon the incorporation of manganese into the zinc selenide lattice. Concentrations of the order 300 p.p.m. were obtained when the element was added to the charge and MnCl(_2) was placed in the reservoir. Higher levels of manganese (~1%) were obtained using chemical vapour transport with iodine as the transport agent. Boules of solid solutions, within the range of compositions from ZnSe to ZnSe(_0.4)S(_0.6) were examined using a transmission electron microscope. The dominant crystallographic defects were found to change from thin twins to stacking faults as the amount of ZnS was increased. The origin of the defects was probably post growth stress. Finally, the anomalous photovoltaic effect was discovered in ZnSe needle crystals, and was explained qualitatively in terms of asymmetrical barriers along the polar axis of the crystal

Improved antimicrobial activity of nisin-incorporated polymer films by formulation change and addition of food grade chelator

Aims: The following polymers were developed: polyethylene (PE), a PE and polyethylene oxide (70% PE and 30% PEO; PE + PEO) blend, PE and nisin (PE + nisin), PE, nisin, and EDTA (PE + nisin + EDTA), and PE + PEO with nisin (PE + PEO + nisin). Methods and Results: Of the polymers tested, PE and PE + PEO did not exhibit any antimicrobial activity against Brochothrix thermosphacta (BT); however, PE + nisin, PE + nisin + EDTA, and PE + PEO + nisin did. Beef surfaces were experimentally inoculated with 3·50 log10 cfu/cm2 of BT, vacuum packaged with each of the five polymers, and held at 4°C for 21 d. After 3 d at 4°C, BT was reduced \u3e 1·70 log10 by PE + nisin and \u3e 3·50 log10 with PE + nisin + EDTA or PE + PEO + nisin. By 21 d at 4°C, BT was reduced to 0·30 log10 cfu/cm2 when treated with PE + PEO + nisin. Conclusions: It appears that PE + PEO + nisin or PE + nisin + EDTA were more effective for reducing BT, as compared to polymers composed of PE + nisin. Significance and Impact of the Study: Nisin-incorporated polymers may control the growth of undesirable bacteria, thereby extending the shelf life and possibly enhancing the microbial safety of meats

Improved antimicrobial activity of nisin-incorporated polymer films by formulation change and addition of food grade chelator

Aims: The following polymers were developed: polyethylene (PE), a PE and polyethylene oxide (70% PE and 30% PEO; PE + PEO) blend, PE and nisin (PE + nisin), PE, nisin, and EDTA (PE + nisin + EDTA), and PE + PEO with nisin (PE + PEO + nisin). Methods and Results: Of the polymers tested, PE and PE + PEO did not exhibit any antimicrobial activity against Brochothrix thermosphacta (BT); however, PE + nisin, PE + nisin + EDTA, and PE + PEO + nisin did. Beef surfaces were experimentally inoculated with 3·50 log10 cfu/cm2 of BT, vacuum packaged with each of the five polymers, and held at 4°C for 21 d. After 3 d at 4°C, BT was reduced \u3e 1·70 log10 by PE + nisin and \u3e 3·50 log10 with PE + nisin + EDTA or PE + PEO + nisin. By 21 d at 4°C, BT was reduced to 0·30 log10 cfu/cm2 when treated with PE + PEO + nisin. Conclusions: It appears that PE + PEO + nisin or PE + nisin + EDTA were more effective for reducing BT, as compared to polymers composed of PE + nisin. Significance and Impact of the Study: Nisin-incorporated polymers may control the growth of undesirable bacteria, thereby extending the shelf life and possibly enhancing the microbial safety of meats

Distributions and abundances of Pacific sardine (Sardinops sagax) and other pelagic fishes in the California Current Ecosystem during spring 2006, 2008, and 2010, estimated from acoustic–trawl surveys

The abundances and distributions of coastal pelagic fish species in the California Current Ecosystem from San Diego to southern Vancouver Island, were estimated from combined acoustic and trawl surveys conducted in the spring of 2006, 2008, and 2010. Pacific sardine (Sardinops sagax), jack mackerel (Trachurus symmetricus), and Pacific mackerel (Scomber japonicus) were the dominant coastal pelagic fish species, in that order. Northern anchovy (Engraulis mordax) and Pacific herring (Clupea pallasii) were sampled only sporadically and therefore estimates for these species were unreliable. The estimates of sardine biomass compared well with those of the annual assessments and confirmed a declining trajectory of the “northern stock” since 2006. During the sampling period, the biomass of jack mackerel was stable or increasing, and that of Pacific mackerel was low and variable. The uncertainties in these estimates are mostly the result of spatial patchiness which increased from sardine to mackerels to anchovy and herring. Future surveys of coastal pelagic fish species in the California Current Ecosystem should benefit from adaptive sampling based on modeled habitat; increased echosounder and trawl sampling, particularly for the most patchy and nearshore species; and directed-trawl sampling for improved species identification and estimations of their acoustic target stre

Biogeochemical Control of Phosphorus Cycling and Primary Production in Lake Michigan

A 3-yr study in Lake Michigan has shown a 27 mmol P m-2 increase in the mass of total P (TP) in the water during spring when the lake is mixed from surface to sediment. This value is an order of magnitude greater than the annual P input from external sources. TP changed in concert with increases in chlorophyll a and organic N and decreases in nitrate and soluble Si. The concentration of soluble reactive PO4-3 (SRP) remained relatively constant throughout the study. We hypothesize that the SRP concentration is maintained by a chemical equilibrium with calcium-phosphate species. The increased mass of TP arises from the sequestering of P by algae which displaces the chemical equilibrium and allows more P to be released to the water from the sediments. Solar irradiance and the duration of mixing determine the magnitude of the spring bloom and the demand for P that must be supplied through the flux of P from the sediments to the overlying water

Indoor Carbon Monoxide: A Case Study in England for Detection and Interventions to Reduce Population Exposure

Background. Potential exposure to carbon monoxide (CO) in private homes is largely unquantified. Aim. To estimate prevalence of potential exposure to CO in residential dwellings and describe associated interventions in an inner-city community. Methods. A housing association in London, Hackney Homes, began fitting CO alarms in the 22,831 local authority homes it is responsible for in January 2010. A gas engineer investigated each alarm activation and recorded the information on a standard form. We undertook a cross-sectional study of all 22,831 homes, using data from these forms. Descriptive analysis was performed, including incidence, monthly variation, cause of alarm activation, and actions taken. Results. Between November 2011 and April 2012, 106 incidents were reported. Of these, 34.6% identified an issue with a gas appliance, and 10.6% identified misuse of cooking methods as the cause of activation. Relevant interventions were put in place, including disconnection of the gas appliance and education around cooking methods. Discussion. Little is known about the burden of CO poisoning in residential dwellings. This study provides important information on the path to quantifying population exposure to CO as well as establishing a possible approach to access this key information and realistic interventions to reduce potential exposure

Disease-modifying therapy prescription patterns in people with multiple sclerosis by age

BACKGROUND: Disease-modifying therapies (DMTs) for multiple sclerosis (MS) are approved for their ability to reduce disease activity, namely clinical relapses and signal changes on magnetic resonance imaging (MRI). Disease activity appears age dependent. Thus, the greatest benefit would be expected in younger people with MS (PwMS) whereas benefits in the elderly are uncertain. METHODS: Real-world data were obtained from PwMS from the North American Research Committee on Multiple Sclerosis (NARCOMS) registry and the US Department of Veterans Affairs Multiple Sclerosis Surveillance Registry (MSSR). RESULTS: 6948 PwMS were surveyed from NARCOMS, and the MSSR had 1719 participants. In younger adult PwMS 40-years old or less, 183 (61.4%) in NARCOMS and 179 (70.5%) in the MSSR were prescribed DMTs. Among PwMS over age 60, 1575 (40.1%) in NARCOMS and 239 (36.3%) in the MSSR were prescribed DMTs. More PwMS in the age group of 31-40 ( CONCLUSION: These findings suggest that DMTs are under-utilized in the younger population and continue to be commonly prescribed in the elderly. Broader access may explain the higher prescription rate of DMTs in US veterans

Reframing Resilience: Equitable Access to Essential Services

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156467/2/risa13492.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156467/1/risa13492_am.pd

Proportional constrained longitudinal data analysis models for clinical trials in sporadic Alzheimer\u27s disease

INTRODUCTION: Clinical trials for sporadic Alzheimer\u27s disease generally use mixed models for repeated measures (MMRM) or, to a lesser degree, constrained longitudinal data analysis models (cLDA) as the analysis model with time since baseline as a categorical variable. Inferences using MMRM/cLDA focus on the between-group contrast at the pre-determined, end-of-study assessments, thus are less efficient (eg, less power). METHODS: The proportional cLDA (PcLDA) and proportional MMRM (pMMRM) with time as a categorical variable are proposed to use all the post-baseline data without the linearity assumption on disease progression. RESULTS: Compared with the traditional cLDA/MMRM models, PcLDA or pMMRM lead to greater gain in power (up to 20% to 30%) while maintaining type I error control. DISCUSSION: The PcLDA framework offers a variety of possibilities to model longitudinal data such as proportional MMRM (pMMRM) and two-part pMMRM which can model heterogeneous cohorts more efficiently and model co-primary endpoints simultaneously

Evidence for donor strand complementation in the biogenesis of Haemophilus influenzae haemagglutinating pili

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73758/1/j.1365-2958.2000.01816.x.pd