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This white paper identifies knowledge gaps and new challenges in healthcare epidemiology research, assesses the progress made toward addressing research priorities, provides the Society for Healthcare Epidemiology of America (SHEA) Research Committee's recommendations for high-priority research topics, and proposes a road map for making progress toward these goals. It updates the 2010 SHEA Research Committee document, “Charting the Course for the Future of Science in Healthcare Epidemiology: Results of a Survey of the Membership of SHEA,” which called for a national approach to healthcare-associated infections (HAIs) and a prioritized research agenda. This paper highlights recent studies that have advanced our understanding of HAIs, the establishment of the SHEA Research Network as a collaborative infrastructure to address research questions, prevention initiatives at state and national levels, changes in reporting and payment requirements, and new patterns in antimicrobial resistance.
To investigate whether inadequate dose to Point-A necessitates treatment plan changes in a time of computed tomography (CT)-image-guided brachytherapy treatment planning for cervix cancer.
Materials and methods
A total of 125 tandem and ovoid insertions from 25 cervix patients treated were reviewed. CT-image-based treatment planning was carried out for each insertion. Point-A is identified and the dose documented; however, dose optimisation in each plan was based on covering target while limiting critical organ doses (PlanTarget). No attempts were made to equate prescription and Point-A dose. For each insertion, a second hypothetical treatment plan was generated by prescribing dose to Point-A (PlanPoint-A). Plans were inter-compared using dose–volume histogram analyses.
A total of 250 treatment plans were analysed. For the study population, the median cumulative dose at Point-A was 80 Gy (range 70–95) for PlanTarget compared with 84·25 Gy for PlanPoint-A. Bladder and rectal doses were higher for PlanPoint-A compared with PlanTarget (p < 0·0001). Target D90 did not correlate with Point-A dose (p = 0·60).
Depending on applicator geometry, tumour size and patient anatomy, Point-A dose may vary in magnitude compared with prescription dose. Treatment plan modifications purely based on inadequate Point-A dose are unnecessary, as these may result in higher organ-at-risk doses and not necessarily improve target coverage.
The lattice deformation caused by 100 MeV Ti7+ ion irradiation in Si (100) has been studied using X-ray topographic techniques. An important finding is the appearance of a strain field perpendicular to the ion beam direction in the irradiated region well separated from the projected range of implanted ions. This in-plane strain extends in the bulk of the sample and is not merely confined to the surface. The implanted region has been found to experience an out of plane strain which is expected to be tensile in nature.
We report the nonthermal synthesis of ultrafine crystalline nanoparticles of titanium oxide and titanium nitride. The nanoparticles are formed by gas phase reactions between precursor gases dissociated in the microwave plasma. For the production of titanium nitride, titanium tetraisopropoxide (TTIP) and ammonia or nitrogen precursor gases are used. For titanium oxide production TTIP and oxygen are used as precursor gases. In both cases ultrahigh purity argon serves as a carrier gas and diluent.Transmission electron microscopy (TEM) revealed that the titanium nitride powders so formed were either cubic (TiN) or tetragonal (Ti2N) depending on the operational conditions, particularly the relative nitrogen gas flow rates. Ammonia gas was found to be a much more reactive nitrogen source than molecular nitrogen gas. For the titanium oxide growth an excess of oxygen was utilized to achieve TiO2. Powders collected from the gas phase corresponded to the rutile (tetragonal) phase. However, powders collected from the cavity walls corresponded to the high temperature and pressure (orthorhombic) 13-TiO2. There was also evidence of a polytypically modulated phase of TiO2, with the observed c-periodicity double the parent c-periodicity of the rutile phase. Using a low oxygen flow rate during powder formation led to the formation of orthorhombic Ti3O5 “powders”. The powders were easily sinterable by in situ electron beam annealing in the electron microscope, with an estimated temperature of around 550°C. This is much lower than the temperatures normally required to sinter these materials.
This paper contains a review of the results from the studies at the University of California at Berkeley on various factors influencing the microstructure of the transition zone in concrete. Two types of aggregate, two different cement, and three mineral admixtures were investigated. Using cement paste-polished aggregate composite specimens cured up to three years, X-ray diffraction, scanning electron microscopy, and microhardness testing techniques were used for characterization of the transition zone.
Compared to the transition zone between a quartz aggregate and an ASTM Type I portland cement, transition zones with smaller and less preferentially oriented crystals of calcium hydroxide were obtained when using a Type K expansive cement, or limestone aggregate, or mineral additives, such as condensed silica fume, granulated blast-furnace slag, and fly ash.
Orange-red light emission has been observed for the first time from crystalline silicon nanoparticles produced by gas phase synthesis in a non-thermal microwave plasma. The size and crystalline nature of the particles have been confirmed by transmission electron microscopy and X-ray diffraction. Photoluminescence at 300 K and 77 K has been measured and analyzed. The emission spectra are consistent with quantum mechanical calculations based on a quantum box.
Grain boundary free volume, simply defined as the difference between the volume of a bicrystal and that of a single crystal containing an equal number of atoms, provides a good measure of average grain boundary coordination. Free volume is useful because (a) computer calculations suggest that the grain boundary free volume scales with the grain boundary energy and (b) experimental measurement of free volume may be relatively easier and more direct than that of grain boundary energy. The objective of this paper is to compare the predictions from computer models of grain boundary free volume with experimental measurements.
We investigated the performance of 65nm pFETs whereby the source and drain extensions (SDE) were implanted with Carborane, (C2B10H12) a novel form of molecular species. The high atomic mass of this molecule (146 a.m.u.) and the number of boron atoms transported per ion enables the productivity at low energy required for manufacturing of ultra shallow junctions for advanced scaling. In this investigation, Carborane was implanted at 13 keV to produce a Boron profile near equivalent to that produced by the reference BF2 implant. Results of electrical measurements did not exhibit any compromise in the I-V characteristics in terms of Id-Vg and Id-Vd and Ion-Ioff. External resistance and Vt roll-off shifted slightly with respect to the reference devices. This is attributed to a deeper junction with Carborane due to slight offset in the profile matching. It will be shown that with fully matched profiles, a perfect match of the device characteristics can be achieved.
In 1978, 22 staff members of the National Institute of Virology, Pune, India, were given two doses of human diploid cell antirabies vaccine (HDCV) for primary pre-exposure prophylactic immunization; the interval between the two doses being approximately 4 weeks. Eighteen of these 22 vaccinees were given a booster dose 1 year later. All 18 vaccinees developed protective levels of antibody; most of them had antibody levels exceeding 10 IU/ml.
In 1984, 5 years after the booster dose, 11 (79·0%) of 14 vaccinees tested still possessed neutralizing antibody levels ranging from 0·5 IU/ml to 10 IU/ml. Fourteen days after the administration of a booster dose, the antibody levels ranged from 10 to ≥ 100 IU/ml for all except one vaccinee (5·2 IU/ml). These findings demonstrate that the majority of vaccinees retained detectable neutralizing antibody after pre-exposure prophylaxis for as long as 5 years and that a single booster dose thereafter evoked a good antibody response.
Accurate neuropsychological assessment of older individuals from heterogeneous backgrounds is a major challenge. Education, ethnicity, language, and age are associated with scale level differences in test scores, but item level bias might contribute to these differences. We evaluated several strategies for dealing with item and scale level demographic influences on a measure of executive abilities defined by working memory and fluency tasks. We determined the impact of differential item functioning (DIF). We compared composite scoring strategies on the basis of their relationships with volumetric magnetic resonance imaging (MRI) measures of brain structure. Participants were 791 Hispanic, white, and African American older adults. DIF had a salient impact on test scores for 9% of the sample. MRI data were available on a subset of 153 participants. Validity in comparison with structural MRI was higher after scale level adjustment for education, ethnicity/language, and gender, but item level adjustment did not have a major impact on validity. Age adjustment at the scale level had a negative impact on relationships with MRI, most likely because age adjustment removes variance related to age-associated diseases. (JINS, 2008, 14, 746–759.)
Exposure of Chlorella vulgaris to elevated concentrations of copper, chromium, nickel and zinc led to intracellular
accumulation of high concentrations of these metals. Concomitantly, accumulation of free proline occurred,
depending on the concentration of metals in the external medium or in the cell. The greater the toxicity or
accumulation of a metal, the greater the amount of intracellular proline in algal cells. However, higher
concentrations of copper and chromium were inhibitory to proline accumulation by the test organism. The
accumulation of proline was triggered within a few hours of metal treatment. Test metals also induced lipid
peroxidation; copper was the most efficient inducer whereas zinc was the least. Pretreatment of C. vulgaris with
proline counteracted metal-induced lipid peroxidation and potassium ion efflux. Thus the present work shows a
protective effect of proline on metal toxicity through inhibition of lipid peroxidation.
A natural phytoplankton assemblage from a pond was grown in semicontinuous cultures receiving phosphorus (P) pulses once every 2 or 6 days. The study shows that the structure of phytoplankton assemblage depends on the mode of P supply. Biomass, expressed as total biovolume, was greatest in cultures receiving P pulse once every 2 days. While the total amount of P administered to both pulsed cultures remained similar, differences in structure of the phytoplankton assemblage were observed during the 4 weeks experimental period. The small sized Navicula cryptocephala became dominant in cultures which did not receive P pulses. Therefore, this species seems to be «affinity specialist» well-adapted to a low P concentration. The replacement of the dominant cyanobacterium Gomphosphaeria aponina by the diatoms Navicula cryptocephala and Synedra ulna in the control and P-pulsed cultures might be due to another factor. The large sized Phormidium mucosum and Hormidium sp. were favoured in cultures pulsed with P at the lowest frequency, which seems to be due mainly to their larger P accumulation capacity. Synedra ulna was favoured to the same extent under the 2 and 6-day pulse periods.
The most commonly performed procedure for treating
coronary artery stenosis is percutaneous transluminal
coronary angioplasty (PTCA) and, where the vessel lumen is
severely narrowed, coronary artery bypass grafting (CABG).
In PTCA, regions of atherosclerotic plaques are disrupted,
and the vessel lumen increased by inflating a balloon
catheter. In CABG an autologous saphenous vein into
coronary artery interposition graft is performed in order to
bypass occluded regions of epicardial coronary arteries.
Both interventions cause varying degrees of vascular damage
and the long-term efficacy of these procedures is limited by
a high incidence of neointimal formation and subsequent
vascular restenosis (Bach et al. 1994; Bryan & Angelini, 1994).
The endothelium-derived constrictor peptide, endothelin-1 (ET-1)
(Yanagisawa et al. 1988), also possesses mitogenic
activity on vascular smooth muscle cells (Hirata et al. 1989)
and has been suggested as playing a role in atherosclerosis
(Dashwood et al. 1993; Zeiher et al. 1994) and intimal
hyperplasia (Dashwood et al. 1993; Douglas et al. 1994).