120 research outputs found
Resonant Lifetime of Core-Excited Organic Adsorbates from First Principles
We investigate by first-principles simulations the resonant electron-transfer
lifetime from the excited state of an organic adsorbate to a semiconductor
surface, namely isonicotinic acid on rutile TiO(110). The
molecule-substrate interaction is described using density functional theory,
while the effect of a truly semi-infinite substrate is taken into account by
Green's function techniques. Excitonic effects due to the presence of
core-excited atoms in the molecule are shown to be instrumental to understand
the electron-transfer times measured using the so-called core-hole-clock
technique. In particular, for the isonicotinic acid on TiO(110), we find
that the charge injection from the LUMO is quenched since this state lies
within the substrate band gap. We compute the resonant charge-transfer times
from LUMO+1 and LUMO+2, and systematically investigate the dependence of the
elastic lifetimes of these states on the alignment among adsorbate and
substrate states.Comment: 24 pages, 6 figures, to appear in Journal of Physical Chemistry
Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO2: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J-V Hysteresis
Methylammonium lead iodide (MAPI) cells of the design FTO/sTiO2/ mpTiO2/MAPI/Spiro-OMeTAD/Au, where FTO is fluorine-doped tin oxide, sTiO2 indicates solid-TiO2, and mpTiO2 is mesoporous TiO2, are studied using transient photovoltage (TPV), differential capacitance, charge extraction, current interrupt, and chronophotoamperometry. We show that in mpTiO2/MAPI cells there are two kinds of extractable charge stored under operation: a capacitive electronic charge (∼0.2 μC/ cm2) and another, larger charge (40 μC/cm2), possibly related to mobile ions. Transient photovoltage decays are strongly double exponential with two time constants that differ by a factor of ∼5, independent of bias light intensity. The fast decay (∼1 μs at 1 sun) is assigned to the predominant charge recombination pathway in the cell. We examine and reject the possibility that the fast decay is due to ferroelectric relaxation or to the bulk photovoltaic effect. Like many MAPI solar cells, the studied cells show significant J−V hysteresis. Capacitance vs open circuit voltage (Voc) data indicate that the hysteresis involves a change in internal potential gradients, likely a shift in band offset at the TiO2/MAPI interface. The TPV results show that the Voc hysteresis is not due to a change in recombination rate constant. Calculation of recombination flux at Voc suggests that the hysteresis is also not due to an increase in charge separation efficiency and that charge generation is not a function of applied bias. We also show that the J−V hysteresis is not a light driven effect but is caused by exposure to electrical bias, light or dark.</div
Surgical treatment of primitive gastro-intestinal lymphomas: a systematic review
Primitive Gastrointestinal Lymphomas (PGIL) are uncommon tumours, although time-trend analyses have demonstrated an increase. The role of surgery in the management of lymphoproliferative diseases has changed over the past 40 years. Nowadays their management is centred on systemic treatments as chemo-/radio- therapy. Surgery is restricted to very selected indications, always discussed in a multidisciplinary setting. The aim of this systematic review is to evaluate the actual role of surgery in the treatment of PGIL
Which New Approaches to Tackling Neglected Tropical Diseases Show Promise?
This PLoS Medicine Debate examines the different approaches that can be taken to tackle neglected tropical diseases (NTDs). Some commentators, like Jerry Spiegel and colleagues from the University of British Columbia, feel there has been too much focus on the biomedical mechanisms and drug development for NTDs, at the expense of attention to the social determinants of disease. Burton Singer argues that this represents another example of the inappropriate “overmedicalization” of contemporary tropical disease control. Peter Hotez and colleagues, in contrast, argue that the best return on investment will continue to be mass drug administration for NTDs
Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF
M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe
Evaluation of appendicitis risk prediction models in adults with suspected appendicitis
Background
Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis.
Methods
A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis).
Results
Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent).
Conclusion
Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified
Identificazioni di marker molecolari per la differenziazione di un vaccino IBV genotipo QX
IBV genotype QX causes suf cient disease in Europe for several commercial com- panies to have started developing live attenuated vaccines. Here, one of those vac- cines (L1148) was fully consensus sequenced alongside its progenitor eld strain (1148-A) to determine vaccines markers, thereby enabling detection on farms. Twenty eight single nucleotide substitutions were associated with the 1148-A atten- uation, of which any combination can identify vaccine L1148 in the eld. Sixteen substitutions resulted in amino acid coding changes of which half were in spike. One change in the 1b gene altered the normally highly conserved nal 5 nucleotides of the transcription regulatory sequence of the S gene, common to all IBV QX genes. No mutations can currently be associated with the attenuation process. Field vac- cination strategies would greatly bene t by such comparative sequence data being mandatorily submitted to regulators prior to vaccine release following a successful registration process
THE PIGEON (COLUMBA LIVIA) IS NOT SENSITIVE TO AVIAN METAPNEUMOVIRUS SUBTYPE B AND DOES NOT PLAY ANY ROLE IN VIRUS SPREAD IN EXPERIMENTAL CONDITIONS
Avian metapneumovirus (AMPV) causes an upper respiratory tract infection in turkeys leading to turkey rhinotracheitis. In other avian species, including chickens, it is also involved in the aetiology of multifactorial diseases such as swollen head syndrome. Sensitivity of wild birds to AMPV and their role in maintaining and spreading the virus to poultry is still a matter of debate. Recently the sensitivity of pigeons to AMPV of subtype A or B has been claimed, based on very limited PCR detections from wild or experimentally infected birds. In order to have conclusive evidence regarding the sensitivity of pigeons to AMPV of subtype B and its role in spreading the virus to turkeys, two experimental trials were planned in secure isolation conditions. In trial 1 two isolators were modified to host turkeys and pigeons in the same environment, separated only by a net. Drinkers were shared between groups. 16 Pigeons were infected with AMPV and housed in one isolator with na\uefve turkeys. Similarly turkeys were infected and housed with na\uefve pigeons. Additional turkeys and pigeons were kept in different isolators as uninfected controls. Post-infection clinical signs, virus shedding and immune response were assessed for three weeks. In trial 2, commercial two-weeks old turkeys were divided in two groups of ten and housed in two different isolators. Birds in isolator A were challenged as previously described. Four days post-infection, five 7 weeks old na\uefve pigeons were introduced in the isolator A and kept with the infected turkeys for 24 hours, then removed, sprayed with 0,5 % of Wirkon S solution. After 10 minutes, pigeons were rinsed with water, dried, and introduced in the isolator B, where 10 na\uefve turkeys were housed. Clinical sign were monitored for 10 days. Pigeons were found refractory to AMPV experimental infection and neither able to spread the virus to na\uefve turkeys. Our paper shows that pigeons are highly unlikely to play any relevant role in the environmental spread of subtype B AMPV. Pigeons are not biological vector or reservoir species for AMPV subtype B
Evidenze sperimentali della resistenza del Piccione (Columba Livia) all\u2019infezione da Metapneumovirus aviare e della sua irrilevanza nella trasmissione dell\u2019infezione al tacchino
Avian metapneumovirus (AMPV) causes an upper respiratory tract infection in turkeys leading to turkey rhinotracheitis. In other avian species, including chickens, it is also involved in the etiology of multifactorial diseases such as swollen head syndrome. Sensitivity of wild birds to AMPV and their role in maintaining and spreading the virus to poultry is still a matter of debate. Recently the sensitivity of pigeons to AMPV of subtype A or B has been claimed, based on very limited PCR detections from wild or experimentally infected birds. In order to have conclusive evidence regarding the sensitivity of pigeons to AMPV of subtype B and its role in spreading the virus to turkeys, two experimental trials were planned in secure isolation conditions. In trial 1 two isolators were modified to host turkeys and pigeons in the same environment, separated only by a net. Drinkers were shared between groups. Pigeons were infected with AMPV and housed in one isolator with na\uefve turkeys. Similarly turkeys were infected and housed with na\uefve pigeons. Additional turkeys and pigeons were kept in different isolators as uninfected controls. Post-infection clinical signs, virus shedding and immune response were assessed for three weeks. In trial 2, commercial two-weeks old turkeys were divided in two groups and housed in two different isolators. Birds in isolator A were challenged as previously described. Four days post-infection, 7 weeks old na\uefve pigeons were introduced in the isolator A and kept with the infected turkeys for 24 hours, then removed, sprayed with 0,5 % of Wirkon S\uae solution. After 10 minutes, pigeons were rinsed with water, dried, and introduced in the isolator B, where 10 na\uefve turkeys were housed. Clinical sign were monitored for 10 days. Pigeons were found refractory to AMPV experimental infection and neither able to spread the virus to na\uefve turkeys. Our paper shows that pigeons are highly unlikely to play any relevant role in the environmental spread of subtype B AMPV. Pigeons are not biological vector or reservoir species for AMPV subtype B
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