Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 630
Filtrar
1.
World J Virol ; 13(1): 91149, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38616849

RESUMO

BACKGROUND: Metabolic dysfunction-associated steatotic liver disease (MASLD), formally known as nonalcoholic fatty liver disease, is the most common chronic liver disease in the United States. Patients with MASLD have been reported to be at a higher risk of developing severe coronavirus disease 2019 (COVID-19) and death. However, most studies are single-center studies, and nationwide data in the United States is lacking. AIM: To study the influence of MASLD on COVID-19 hospitalizations during the initial phase of the pandemic. METHODS: We retrospectively analyzed the 2020 National Inpatient Sample (NIS) database to identify primary COVID-19 hospitalizations based on an underlying diagnosis of MASLD. A matched comparison cohort of COVID-19 hospitalizations without MASLD was identified from NIS after 1: N propensity score matching based on gender, race, and comorbidities, including hypertension, heart failure, diabetes, and cirrhosis. The primary outcomes included inpatient mortality, length of stay, and hospitalization costs. Secondary outcomes included the prevalence of systemic complications. RESULTS: A total of 2210 hospitalizations with MASLD were matched to 2210 hospitalizations without MASLD, with a good comorbidity balance. Overall, there was a higher prevalence of severe disease with more intensive care unit admissions (9.5% vs 7.2%, P = 0.007), mechanical ventilation (7.2% vs 5.7%, P = 0.03), and septic shock (5.2% vs 2.7%, P <0.001) in the MASLD cohort than in the non-MASLD cohort. However, there was no difference in mortality (8.6% vs 10%, P = 0.49), length of stay (5 d vs 5 d, P = 0.25), and hospitalization costs (42081.5 $ vs 38614$, P = 0.15) between the MASLD and non-MASLD cohorts. CONCLUSION: The presence of MAFLD with or without liver cirrhosis was not associated with increased mortality in COVID-19 hospitalizations; however, there was an increased incidence of severe COVID-19 infection. This data (2020) predates the availability of COVID-19 vaccines, and many MASLD patients have since been vaccinated. It will be interesting to see if these trends are present in the subsequent years of the pandemic.

2.
Artigo em Inglês | MEDLINE | ID: mdl-38604401

RESUMO

BACKGROUND: As the number of total shoulder arthroplasty (TSA) procedures increases, there is a growing interest in improving patient outcomes, limiting costs, and optimizing efficiency. One approach has been to transition these surgeries to an outpatient setting. Therefore, the purpose of this study was to conduct an age-stratified analysis comparing the 90-day postoperative outcomes of primary TSA in the same-day discharge (SDD) and inpatient (IP) settings with a specific focus on the super-elderly. METHODS: This retrospective study included all patients who underwent primary anatomic or reverse TSA between January 2018 and December 2021 in ambulatory and inpatient settings. The outcome measures included LOS, complications, hospital charges, ED utilization, readmissions, and reoperations within 90-days following TSA. Patients with LOS ≤8 hours were considered as SDD, and those with LOS >8 hours were considered as IP. P <0.05 was considered statistically significant. RESULTS: There were 121 and 174 procedures performed in SDD and IP settings, respectively. There were no differences in comorbidity indices between the SDD and IP groups (ASA score P=0.12, ECI P=0.067). The SDD cohort was younger than the IP group (SDD 67.0 years vs. 73.0 IP years, P<0.001), and the SDD group higher rate of intraoperative tranexamic acid use (P=0.015) and lower estimated blood loss (P=0.009). There were no differences in 90-day overall minor (P=0.20) and major complications (P=1.00), ED utilization (P=0.63), readmission (P=0.25) or reoperation (P =0.51) between the SDD and IP groups. When stratified by age, there were no differences in overall major (P=0.80) and minor (P=0.36) complications among the groups. However, the LOS was directly correlated with increasing age (LOS=8.4 hours in ≥65 to < 75-year cohort vs. LOS=25.9 hours in ≥80-year cohort; P<0.001). There were no differences in hospital charges between SDD and IP primary TSA in all 3 age groups (P=0.82). CONCLUSION: SDD TSA has a shorter LOS without increasing postoperative major and minor complications, ED encounters, readmissions, or reoperations. Older age was not associated with an increase in the complication profile or hospital charges even in the SDD setting, although it was associated with increased LOS in the IP group. These results suggest that TSA can be safely performed expeditiously in an outpatient setting. LEVEL OF EVIDENCE: Level III; Retrospective Comparative Study.

3.
Proc Natl Acad Sci U S A ; 121(15): e2317769121, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38564633

RESUMO

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by social and communication deficits and repetitive behaviors. The genetic heterogeneity of ASD presents a challenge to the development of an effective treatment targeting the underlying molecular defects. ASD gating charge mutations in the KCNQ/KV7 potassium channel cause gating pore currents (Igp) and impair action potential (AP) firing of dopaminergic neurons in brain slices. Here, we investigated ASD gating charge mutations of the voltage-gated SCN2A/NaV1.2 brain sodium channel, which ranked high among the ion channel genes with mutations in individuals with ASD. Our results show that ASD mutations in the gating charges R2 in Domain-II (R853Q), and R1 (R1626Q) and R2 (R1629H) in Domain-IV of NaV1.2 caused Igp in the resting state of ~0.1% of the amplitude of central pore current. The R1626Q mutant also caused significant changes in the voltage dependence of fast inactivation, and the R1629H mutant conducted proton-selective Igp. These potentially pathogenic Igp were exacerbated by the absence of the extracellular Mg2+ and Ca2+. In silico simulation of the effects of these mutations in a conductance-based single-compartment cortical neuron model suggests that the inward Igp reduces the time to peak for the first AP in a train, increases AP rates during a train of stimuli, and reduces the interstimulus interval between consecutive APs, consistent with increased neural excitability and altered input/output relationships. Understanding this common pathophysiological mechanism among different voltage-gated ion channels at the circuit level will give insights into the underlying mechanisms of ASD.


Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Canais de Sódio Disparados por Voltagem , Humanos , Transtorno do Espectro Autista/genética , Transtorno Autístico/genética , Encéfalo , Mutação
4.
ACS Appl Mater Interfaces ; 16(12): 15435-15445, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38470565

RESUMO

Achieving robust underwater adhesion remains challenging. Through generations of evolution, marine mussels have developed an adhesive system that allows them to anchor onto wet surfaces. Scientists have taken varied approaches to developing mussel-inspired adhesives. Mussel foot proteins are rich in lysine residues, which may play a role in the removal of salts from surfaces. Displacement of water and ions on substrates could then enable molecular contact with surfaces. The necessity of cations for underwater adhesion is still in debate. Here, we examined the performance of a methacrylate polymer containing quaternary ammonium and catechol groups. Varying amounts of charge in the polymers were studied. As opposed to protonated amines such as lysine, quaternary ammonium groups offer a nonreactive cation for isolating effects from only charge. Results shown for dry bonding demonstrated that cations tended to decrease bulk cohesion while increasing surface interactions. Stronger interactions at surfaces, along with weaker bulk bonding, indicate that cations decreased the cohesive forces. When under salt water, overall bulk adhesion also dropped with higher cation loadings. Surface attachment under salt water also dropped, indicating that the polymer cations could not displace surface waters or sodium ions. Salt did, however, appear to shield bulk cation-cation repulsions. These studies help to distinguish influences upon bulk cohesion from attachment at surfaces. The roles of cations in adhesion are complex, with both cohesive and surface bonding being relevant in different ways, sometimes even working in opposite directions.

5.
Chronic Illn ; : 17423953241241759, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38532693

RESUMO

OBJECTIVE: The clinical aspects of lung cancer patients are well-studied. However, healthcare charge patterns have yet to be explored through a large-scale representative population-based sample investigating differences by socioeconomic factors and comorbidities. AIM: To identify how comorbidities associated with healthcare charges among lung cancer patients. METHODS: We examined the characteristics of the patient sample and the association between comorbidity status (diabetes, hypertension, or both) and healthcare charge. Multivariate survey linear regression models were used to estimate the association. We also investigated sub-group association through various patient and socioeconomic factors. RESULTS: Of 212,745 lung cancer patients, 68.5% had diabetes and/or hypertension. Hospital charges were higher in the population with comorbidities. The results showed that lung cancer patients with comorbidities had 9.4%, 5.1%, and 12.0% (with diabetes, hypertension, and both, respectively) higher hospital charges than those without comorbidities. In sub-group analysis, Black patients also showed a similar trend across socioeconomic (i.e. household income and primary payer) and racial (i.e. White, Black, Hispanic, and Asian/Pacific Islander) factors. DISCUSSION: Black patients may be significantly financially burdened because of the prevalence of comorbidities and low-income status. More work is required to ensure healthcare equality and promote access to care for the uninsured, low-income, and minority populations because comorbidities common in these populations can create more significant financial barriers.

6.
World J Surg ; 2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38459712

RESUMO

BACKGROUND: Studies show that reducing the length of hospital stay (LOS) for surgical patients leads to cost savings. We hypothesize that LOS has a nonlinear relationship to cost of care and reduction may not have a meaningful impact on it. We have attempted to define the relationship of LOS to cost of care. We utilized the itemized bill, generated in real time, for hospital services. MATERIALS: Adult patients admitted under General, Neuro, and Orthopedic surgery over a 3-month period, with an LOS between 4 and 14 days, were the study population. Itemized bill details were analyzed. Charges in Pakistani rupees were converted to US dollar. Ethical exemption for study was obtained. RESULTS: Of the 853 patients, 38% were admitted to General Surgery, 27% to Neurosurgery, and 35% to Orthopedics. A total of 64% of the patients had an LOS between 4 and 6 days; 36% had an LOS between 7 and 14 days. Operated and conservatively managed constituted 82% and 18%, respectively. Mean total charge for operated patients was higher $3387 versus $1347 for non-operated ones. LOS was seen to have a nonlinear relationship to in-hospital cost of care. The bulk of cost was centered on the day of surgery. This was consistent across all services. The last day of stay contributed 2.4%-3.2% of total charge. CONCLUSIONS: For surgical patients, the cost implications rapidly taper in the postoperative period. The contribution of the last day of stay cost to total cost is small. For meaningful cost containment, focus needs to be on the immediate perioperative period.

7.
J Mol Model ; 30(4): 100, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38466474

RESUMO

CONTEXT: A comparative study of the change in different properties of electronic and structural of the free 1H-indole-2,3-dione molecule and its complexes has been obtained. HOMA analysis was performed to investigate the effects of lithium sodium and potassium cations on the aromaticity of lithium sodium and potassium complexes of 1H-indole-2,3-dione. METHODS: Several 1H-indole-2,3-dione complexes with lithium, sodium, and potassium cations were optimized at the B3LYP/6-311G(d,p) level. The cation and π interaction has been investigated from different aspects, including interaction energy calculations, charge transfer values, and changes in the aromaticity of the ring upon complexation. The charge transfer and natural population analysis for the complexes were performed with the natural bond orbital (NBO) analysis. The properties of bond critical points in complexes were studied by applying the quantum theory of atoms in molecules (QTAIM). Finally, the aromaticity change of phenyl induced upon complex formation was evaluated by applying the harmonic oscillator model of aromaticity (HOMA). [Li-INa]+ and [[Li-INb]+ were optimized with the wB97XD function using a version of Grimme's D2 dispersion model, and the absorption energy was compared with the calculation made with the B3LYP functional.

8.
Plast Surg (Oakv) ; 32(1): 11-18, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38433808

RESUMO

Introduction: Reduction mammoplasty (RM) is one of the most common operations performed in plastic surgery. While US national surgical expenditures have risen in recent years, studies have reported decreasing reimbursement rates for plastic surgeons. The purpose of this study is to characterize the trends in charges and payments for a common plastic surgery operation, ambulatory RM, for facilities and physicians. Methods: A Medicare patient records database was used to capture hospital, surgeon, and anesthesiologist charges and payments for ambulatory RM from 2005 to 2014. Values were adjusted for inflation. A ratio of hospital to surgeon charges and payments were calculated: charge multiplier (CM) and payment multiplier (PM), respectively. Charges, payments, Charlson comorbidity index, CM, and PM values were analyzed for trends. Results: This study included 1001 patients. During the study period, the facility charge for RM per patient increased from $8477 to $11,102 (31% increase; p < .0005), and the surgeon charge increased from $7088 to $7199 (2% increase; p = .0009). Facility payments increased from $3661 to $3930 (7% increase; p < .0005), and surgeon payments decreased from $1178 to $1002 (15% decrease; p < .0005). CM increased from 1.2 to 1.54, and PM increased from 3.11 to 3.92. Conclusions: Charges and payments to facilities for ambulatory RM increased disproportionately to that of surgeons, likely due in part to rising administrative costs in health care delivery. This may disincentivize plastic surgeons from offering RM at hospital-based surgical centers, limiting patient access to this operation.


Introduction: La mammoplastie de réduction (MR) est l'une des interventions les plus courantes pratiquées en chirurgie plastique. Alors que les dépenses chirurgicales aux États-Unis ont augmenté au niveau national au cours des dernières années, les études ont signalé une diminution des taux de remboursement pour les chirurgiens plasticiens. L'objectif de cette étude est de définir les tendances dans les frais et paiements pour une intervention courante de chirurgie plastique, une MR ambulatoire, pour les établissements et pour les médecins. Méthodes: Une base de données des dossiers de patients Medicare a été utilisée pour collecter les frais pour les hôpitaux, les chirurgiens et les anesthésiologistes ainsi que les paiements pour MR ambulatoires de 2005 à 2014. Les valeurs ont été ajustées pour tenir compte de l'inflation. Des ratios des frais hôpital/chirurgien et des paiements ont été calculés : respectivement, un facteur de multiplication des frais (MF) et des paiements (MP). Les tendances de la valeur des frais, des paiements, de l'indice de comorbidité de Charlson, du MF et du MP ont été analysées. Résultats: Cette étude a inclus 1001 patients. Au cours de la période de l'étude, les frais pour MR par patient à la charge de l'établissement ont augmenté de 8 477 $ à 11 102 $, soit une augmentation de 31 % (P < 0,0005) et les frais du chirurgien sont passés de 7 088 $ à 7 199 $, soit une augmentation de 2 % (P = 0,0009). Les paiements de l'établissement ont augmenté de 3 661 $ à 3 930 $, soit une augmentation de 7 % (P < 0,0005) et les paiements du chirurgien ont diminué de 1 178 $ à 1 002 $, soit une diminution de 15 % (P < 0,0005). Le facteur MF est passé de 1,2 à 1,54 et le facteur MP est passé de 3,11 à 3,92. Conclusions: Les frais et paiements aux établissements pour MR ambulatoire ont augmenté de manière disproportionnée par rapport à ceux des chirurgiens, probablement en partie à cause de l'augmentation des coûts administratifs croissants de l'administration des soins. Cela pourrait inciter les chirurgiens plasticiens à ne plus offrir de MR dans les centres chirurgicaux hospitaliers et pourrait donc limiter l'accès des patients à cette opération.

9.
Appl Radiat Isot ; 206: 111231, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38364612

RESUMO

In this study, electric quadrupole transition properties in some even-even Ti nuclei have been investigated by using different effective charges and interactions. In this respect, B(E2) transition rates, deformation parameters and intrinsic quadrupole moments have been calculated. In calculations, NuShellX code has been used to calculated one body matrix elements (OBDM). Theoretical calculations on these quantities have been compared with the experimental results, and it has been seen that theoretical values obtained by using the kb3 and vpnp interactions and Bohr Mottelson (B-M) and Standard (S-T) effective charges are close to the corresponding experimental results.

10.
Turk J Haematol ; 41(1): 1-8, 2024 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-38374587

RESUMO

Objective: Acute promyelocytic leukemia (APL) is associated with an elevated risk of developing disseminated intravascular coagulation (DIC). The purpose of this study was to assess the outcomes of hospitalizations related to DIC in APL and their impact on healthcare. Materials and Methods: This study entailed a cross-sectional and retrospective analysis of the US National Inpatient Sample database. We identified adults with APL and categorized them into groups of patients with and without DIC. Our focus areas included in-hospital mortality, length of stay, charges, and complications associated with DIC. Unadjusted odds ratios/coefficients were computed in univariate analysis, followed by adjusted odds ratios (aOR)/coefficients from multivariate analysis that accounted for confounding factors. Results: Our analysis revealed that APL patients with DIC had a substantially higher aOR for mortality (aOR: 6.68, 95% confidence interval [CI]: 4.76-9.37, p<0.001) and a prolonged length of stay (coefficient: 10.28 days, 95% CI: 8.48-12.09, p<0.001) accompanied by notably elevated total hospital charges (coefficient: $215,512 [95% CI: 177,368-253,656], p<0.001), thereby emphasizing the reality of extended medical care and economic burden. The presence of DIC was associated with increased odds of sepsis, vasopressor support, pneumonia, acute respiratory failure, intubation/mechanical ventilation, and acute kidney injury, reflecting heightened vulnerability to these complications. Patients with DIC demonstrated significantly higher odds ratios for major bleeding, intracranial hemorrhage, gastrointestinal bleeding, red blood cell transfusion, platelet transfusion, fresh frozen plasma transfusion, and cryoprecipitate transfusion, highlighting the pronounced hematological risks posed by DIC. Conclusion: This study has revealed the significant associations between DIC in APL and various outcomes, underscoring the clinical and economic implications of these conditions. The hematological risks further increase patients' vulnerability to bleeding events and the need for transfusions.


Assuntos
Coagulação Intravascular Disseminada , Leucemia Promielocítica Aguda , Adulto , Humanos , Leucemia Promielocítica Aguda/complicações , Leucemia Promielocítica Aguda/epidemiologia , Leucemia Promielocítica Aguda/terapia , Coagulação Intravascular Disseminada/epidemiologia , Coagulação Intravascular Disseminada/etiologia , Coagulação Intravascular Disseminada/terapia , Estudos Retrospectivos , Transfusão de Componentes Sanguíneos/efeitos adversos , Estudos Transversais , Plasma , Hemorragia , Hospitais , Atenção à Saúde
11.
Antimicrob Resist Infect Control ; 13(1): 27, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38424606

RESUMO

BACKGROUND: Although there is a growing concern and policy regarding infections or colonization caused by resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), the prognosis of MRSA infections compared to that of methicillin-susceptible Staphylococcus aureus (MSSA) infections remains controversial. Moreover, there have not been any studies comparing both the burden of disease and its impact on the healthcare economy between MRSA infection and colonization while adjusting for confounding factors. These comparisons are crucial for developing effective infection control measures and healthcare policies. We aimed to compare the disease and economic burden between MRSA and MSSA infections and between MRSA infection and colonization. METHODS: We retrospectively investigated data of 496 in-patients with MRSA or MSSA infections and of 1178 in-patients with MRSA infections or MRSA colonization from a university hospital in Japan from 2016 to 2021. We compared in-hospital mortality, length of stay, and hospital charges between in-patients with MRSA and MSSA infections and those with MRSA infections and MRSA colonization using multiple regressions. We combined surveillance data, including all microbiological test results, data on patients with infections, treatment histories, and clinical outcomes, to create the datasets. RESULTS: There was no statistically significant difference in in-hospital mortality rates between matched MRSA vs. MSSA infections and MRSA infection vs. colonization. On the contrary, the adjusted effects of the MRSA infection compared to those of MSSA infection on length of stay and hospital charges were 1.21-fold (95% confidence interval [CI] 1.03-1.42, P = 0.019) and 1.70-fold (95% CI 1.39-2.07, P < 0.00001), respectively. The adjusted effects of the MRSA infection compared to those of MRSA colonization on length of stay and hospital charges were 1.41-fold (95% CI 1.25-1.58, P < 0.00001) and 1.53-fold (95% CI 1.33-1.75, P < 0.00001), respectively. Regarding confounding factors, hemodialysis or hemofiltration was consistently identified and adjusted for in the multiple regression analyses comparing MRSA and MSSA infections, as well as MRSA infection and MRSA colonization. CONCLUSIONS: MRSA infection was associated with longer length of stay and higher hospital charges than both MSSA infection and MRSA colonization. Furthermore, hemodialysis or hemofiltration was identified as a common underlying factor contributing to increased length of stay and hospital charges.


Assuntos
Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Humanos , Estudos Retrospectivos , Estresse Financeiro , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus , Hospitais Universitários
12.
Environ Sci Pollut Res Int ; 31(13): 20621-20636, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38381294

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) in soil are potentially harmful to human health. However, the use of photocatalysis technology to treat soil contaminated with PAHs remains challenging. Therefore, TiO2/α-FeOOH composite photocatalyst has been synthesized by hydrothermal method and sol-gel method and applied to photocatalytic degradation of fluoranthene in soil. The morphology, elements, crystal structure, optical properties, electrochemical characteristics, and photocatalytic activity of TiO2/α-FeOOH have been characterized. Results showed that TiO2 is tightly fixed on the surface of α-FeOOH, and TiO2/α-FeOOH had higher photocatalytic activity on photocatalytic degradation of fluoranthene in soil under simulated sunlight. The degradation efficiency of TiO2/α-FeOOH is 3.0 and 4.8 times higher than that of TiO2 and α-FeOOH, respectively. This is attributed to enhanced photocatalytic ability by enhancing the transfer capacity of electrons and holes and broadening the spectrum absorption range. The highest degradation efficiency was achieved when the pH of the soil is neutral, the ratio of water/soil is 10:1, and the dosage of catalyst is 50 mg/g. In addition, it was proved that •O2-, h+, and 1O2 are the main active substances in the photocatalysis of TiO2/α-FeOOH. The possible mechanism of a Z-type electron transfer structure was also proposed. The degradation products of fluoranthene were detected, and the degradation pathway was deduced.


Assuntos
Compostos de Ferro , Minerais , Hidrocarbonetos Policíclicos Aromáticos , Solo , Humanos , Fluorenos , Luz Solar
13.
J Comput Chem ; 45(13): 1017-1032, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38216516

RESUMO

Partial charges are a central concept in general chemistry and chemical biology, yet dozens of different computational definitions exist. In prior work [Cho et al., ChemPhysChem 21, 688-696 (2020)], we showed that these can be reduced to at most three 'principal components of ionicity'. The present study addressed the dependence of computed partial charges q on 1-particle basis set and (for WFT methods) n -particle correlation treatment or (for DFT methods) exchange-correlation functional, for several representative partial charge definitions such as QTAIM, Hirshfeld, Hirshfeld-I, HLY (electrostatic), NPA, and GAPT. Our findings show that semi-empirical double hybrids can closely approach the CCSD(T) 'gold standard' for this property. In fact, owing to an error compensation in MP2, CCSD partial charges are further away from CCSD(T) than is MP2. The nonlocal correlation is important, especially when there is a substantial amount of nonlocal exchange. Employing range separation proves to be "mostly" not advantageous, while global hybrids perform optimally for 20%-30% Hartree-Fock exchange across all charge types. Basis set convergence analysis shows that an augmented triple-zeta heavy-aug-cc-pV(T+d)Z basis set or a partially augmented jun-cc-pV(T+d)Z basis set is sufficient for Hirshfeld, Hirshfeld-I, HLY, and GAPT charges. In contrast, QTAIM and NPA display slower basis set convergence. It is noteworthy that for both NPA and QTAIM, HF exhibits markedly slower basis set convergence than the correlation components of MP2 and CCSD. Triples corrections in CCSD(T), denoted as CCSD(T)-CCSD, exhibit even faster basis set convergence.

14.
Philos Trans A Math Phys Eng Sci ; 382(2267): 20230038, 2024 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-38219784

RESUMO

The asymptotic structure of null and spatial infinities of asymptotically flat spacetimes plays an essential role in discussing gravitational radiation, gravitational memory effect, and conserved quantities in General Relativity (GR). Bondi, Metzner and Sachs (BMS) established that the asymptotic symmetry group for asymptotically simple spacetimes is the infinite-dimensional BMS group. Given that null infinity is divided into two sets: past null infinity [Formula: see text] and future null infinity [Formula: see text], one can identify two independent symmetry groups: [Formula: see text] at [Formula: see text] and [Formula: see text] at [Formula: see text]. Associated with these symmetries are the so-called BMS charges. A recent conjecture by Strominger suggests that the generators of [Formula: see text] and [Formula: see text] and their associated charges are related via an antipodal reflection map near spatial infinity. To verify this matching, an analysis of the gravitational field near spatial infinity is required. This task is complicated due to the singular nature of spatial infinity for spacetimes with non-vanishing ADM mass. Different frameworks have been introduced in the literature to address this singularity, e.g. Friedrich's cylinder, Ashtekar-Hansen's hyperboloid and Ashtekar-Romano's asymptote at spatial infinity. This paper reviews the role of Friedrich's formulation of spatial infinity in the investigation of the matching of the spin-2 charges on Minkowski spacetime and in the full GR setting. This article is part of a discussion meeting issue 'At the interface of asymptotics, conformal methods and analysis in general relativity'.

15.
ACS Nano ; 18(2): 1485-1495, 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-38175971

RESUMO

Despite the significant progress that has been made in recent years in improving the performance of quantum dot light-emitting devices (QLEDs), the effect of charge imbalance and excess carriers on excitons in red (R) vs green (G) vs blue (B) QLEDs has not been compared or systematically studied. In this work we study the effect of changing the electron (e)/hole (h) supply ratio in the QDs emissive layer (EML) in CdSe-based R-, G-, and B-QLEDs with inverted structure in order to identify the type of excess carriers and investigate their effect on the electroluminescence performance of QLEDs of each color. Results show that in R-QLEDs, the e/h ratio in the EML is >1, whereas in G- and B-QLEDs, the e/h ratio is <1 with charge balance conditions being significantly worse in the case of B-QLEDs. Transient photoluminescence (PL) and steady state PL measurements show that, compared to electrons, holes lead to a stronger Auger quenching effect. Transient electroluminescence (TrEL) results indicate that Auger quenching leads to a gradual decline in the EL performance of the QLEDs after a few microseconds, with a stronger effect observed for positive charging versus negative charging. The results provide insights into the differences in the efficiency behavior of R-, G-, and B-QLEDs and uncover the role of excess holes and poor charge balance in the lower efficiency and EL stability of B-QLEDs.

16.
J Orthop ; 50: 116-121, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38187369

RESUMO

Background: Sickle cell disease (SCD) patients undergo major joint replacement surgeries with significant improvement in quality of life. Previous literature have tried to explore differences in hospital charges and length of stay between patients with and without SCD. The aim of this meta-analysis is to find out if both outcomes are increased for patients with SCD patients compared to those without SCD. Methods: Literature search was conducted and studies that compared hospital charges and length of stay between patients with and without sickle cell disease following major arthroplasties were retrieved. A multivariate meta-analysis was conducted using Random-Effect model with the Restricted Maximum Likelihood (REML) using the Metafor Package in R and Rstudio. Results: Four observational studies were found eligible for the study. The estimated average mean difference based on the random effect model for hospital charges was 7548.50 (95 % CI: 3779.65 to 11317.65) and for length of stay was 2.28 (95 % CI: 1.32 to 3.24) while the prediction interval for the true mean difference for both outcomes were -1810.56 to 16907.56 and -0.01 to 4.57 respectively. Conclusion: This present study showed that hospital charges and length of stay are increased for patients with SCD compared to patients without.

17.
PeerJ ; 12: e16514, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38188154

RESUMO

Background: Optimizing access to high-quality scientific journals has become an important priority for academic departments, including the ability to read the scientific literature and the ability to afford to publish papers in those journals. In this contribution, we assess the question of whether institutional investment in scientific journals aligns with the journals where researchers send their papers for publication, and where they serve as unpaid reviewers and editors. Methods: We assembled a unique suite of information about the publishing habits of our Department of Ecology and Evolutionary Biology, including summaries of 3,540 journal publications by 35 faculty members. These data include economic costs of journals to institutions and to authors, benefits to authors in terms of journal prestige and citation rates, and considerations of ease of reading access for individuals both inside and outside the university. This dataset included data on institutional costs, including subscription pricing (rarely visible to scholars), and "investment" by scholars in supporting journals, such as time spent as editors and reviewers. Results: Our results highlighted the complex set of relationships between these factors, and showed that institutional costs often do not match well with payoffs in terms of benefits to researchers (e.g., citation rate, prestige of journal, ease of access). Overall, we advocate for greater cost-benefit transparency to help compare different journals and different journal business models; such transparency would help both researchers and their institutions in investing wisely the limited resources available to academics.


Assuntos
Evolução Biológica , Ecologia , Humanos , Universidades , Comércio , Editoração
18.
Heliyon ; 10(1): e23404, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38169926

RESUMO

Demand charges are widely used for commercial and industrial consumers. These costs are often not well known, let alone the effects that PV can have on them. This work proposes a methodology to assess the effect of PV on reducing these charges and to optimise the power to be contracted, using techniques taken from exploratory data analysis. This methodology is applied to five case studies of industrial consumers from different sectors in Spain, finding savings between 5 % and 11 % of demand charges in industries with continuous operation and up to 28 % in cases of discontinuous operation. These savings can be even greater if the maximum power that can be contracted is lower than the optimum. The demand charges in Spain consist of a fixed part proportional to the contracted power and a variable part depending on the power peaks exceeding it. Since for the variable part the coincident and non-coincident models coexist, a comparison is made between the two models, finding that in the general case PV users can achieve higher savings with the coincident model.

19.
ACS Nano ; 18(5): 4216-4228, 2024 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-38262067

RESUMO

Fe5-xGeTe2 is a promising two-dimensional (2D) van der Waals (vdW) magnet for practical applications, given its magnetic properties. These include Curie temperatures above room temperature, and topological spin textures─TST (both merons and skyrmions), responsible for a pronounced anomalous Hall effect (AHE) and its topological counterpart (THE), which can be harvested for spintronics. Here, we show that both the AHE and THE can be amplified considerably by just adjusting the thickness of exfoliated Fe5-xGeTe2, with THE becoming observable even in zero magnetic field due to a field-induced unbalance in topological charges. Using a complementary suite of techniques, including electronic transport, Lorentz transmission electron microscopy, and micromagnetic simulations, we reveal the emergence of substantial coercive fields upon exfoliation, which are absent in the bulk, implying thickness-dependent magnetic interactions that affect the TST. We detected a "magic" thickness t ≈ 30 nm where the formation of TST is maximized, inducing large magnitudes for the topological charge density (∼6.45 × 1020 cm-2), and the concomitant anomalous (ρxyA,max ≃22.6 µΩ cm) and topological (ρxyu,T 1≃5 µΩ cm) Hall resistivities at T ≈ 120 K. These values for ρxyA,max and ρxyu,T are higher than those found in magnetic topological insulators and, so far, the largest reported for 2D magnets. The hitherto unobserved THE under zero magnetic field could provide a platform for the writing and electrical detection of TST aiming at energy-efficient devices based on vdW ferromagnets.

20.
J Mol Model ; 30(2): 47, 2024 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-38265671

RESUMO

An outline is given of how to split the n-dimensional space of torsion angles occurring in flexible (bio-)polymers (like alkanes, nucleic acids, or proteins, for instance) into n one-dimensional potential curves. Forthcoming applications will focus on the "protein folding problem," beginning with polyglycine. CONTEXT: In accordance with Euler's topology rules, molecules are considered to be composed of "vertices" (atoms, ligands, bonding sites, functional groups, and bigger fragments). Following Hückel, each vertex is represented by only one basis function. Starting from the "monofocal" hydrids CH[Formula: see text], NH[Formula: see text], OH[Formula: see text], FH, and SiH[Formula: see text], PH[Formula: see text], SH[Formula: see text], ClH as anchor units, "chemionic" Hamiltonians (of individual "chemion ensembles" and proportional nuclear charges) are constructed recursively, together with an appropriate basis set for the first five (normal) alkanes and some related oligomers like primary alcohols, alkyl amines, and alkyl chlorides. METHODS: Standard methods ("Restricted Hartree-Fock RHF" and "Full Configuration Interaction FCI") are used to solve the various stationary Schrödinger equations. Two software packages are indispensable: "SMILES" for integral evaluations over Slater-type orbitals (STO), and "Numerical Recipes" for matrix diagonalizations and inversions. While managing with only two-center repulsion integrals, "implicit multi-center integrations" lead us to the non-empirical fundament of Hoffmann's "Extended-Hückel Theory."

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...