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1.
Nature ; 628(8008): 534-539, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38600387

RESUMO

The emergence of collective order in matter is among the most fundamental and intriguing phenomena in physics. In recent years, the dynamical control and creation of novel ordered states of matter not accessible in thermodynamic equilibrium is receiving much attention1-6. The theoretical concept of dynamical multiferroicity has been introduced to describe the emergence of magnetization due to time-dependent electric polarization in non-ferromagnetic materials7,8. In simple terms, the coherent rotating motion of the ions in a crystal induces a magnetic moment along the axis of rotation. Here we provide experimental evidence of room-temperature magnetization in the archetypal paraelectric perovskite SrTiO3 due to this mechanism. We resonantly drive the infrared-active soft phonon mode with an intense circularly polarized terahertz electric field and detect the time-resolved magneto-optical Kerr effect. A simple model, which includes two coupled nonlinear oscillators whose forces and couplings are derived with ab initio calculations using self-consistent phonon theory at a finite temperature9, reproduces qualitatively our experimental observations. A quantitatively correct magnitude was obtained for the effect by also considering the phonon analogue of the reciprocal of the Einstein-de Haas effect, which is also called the Barnett effect, in which the total angular momentum from the phonon order is transferred to the electronic one. Our findings show a new path for the control of magnetism, for example, for ultrafast magnetic switches, by coherently controlling the lattice vibrations with light.

2.
Nature ; 576(7787): 416-422, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31853084

RESUMO

Magnetic topological insulators are narrow-gap semiconductor materials that combine non-trivial band topology and magnetic order1. Unlike their nonmagnetic counterparts, magnetic topological insulators may have some of the surfaces gapped, which enables a number of exotic phenomena that have potential applications in spintronics1, such as the quantum anomalous Hall effect2 and chiral Majorana fermions3. So far, magnetic topological insulators have only been created by means of doping nonmagnetic topological insulators with 3d transition-metal elements; however, such an approach leads to strongly inhomogeneous magnetic4 and electronic5 properties of these materials, restricting the observation of important effects to very low temperatures2,3. An intrinsic magnetic topological insulator-a stoichiometric well ordered magnetic compound-could be an ideal solution to these problems, but no such material has been observed so far. Here we predict by ab initio calculations and further confirm using various experimental techniques the realization of an antiferromagnetic topological insulator in the layered van der Waals compound MnBi2Te4. The antiferromagnetic ordering  that MnBi2Te4  shows makes it invariant with respect to the combination of the time-reversal and primitive-lattice translation symmetries, giving rise to a ℤ2 topological classification; ℤ2 = 1 for MnBi2Te4, confirming its topologically nontrivial nature. Our experiments indicate that the symmetry-breaking (0001) surface of MnBi2Te4 exhibits a large bandgap in the topological surface state. We expect this property to eventually enable the observation of a number of fundamental phenomena, among them quantized magnetoelectric coupling6-8 and axion electrodynamics9,10. Other exotic phenomena could become accessible at much higher temperatures than those reached so far, such as the quantum anomalous Hall effect2 and chiral Majorana fermions3.

3.
Langenbecks Arch Surg ; 409(1): 144, 2024 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-38684518

RESUMO

INTRODUCTION: Endometriosis is a common condition affecting 5 to 10% of women of childbearing age. The true incidence of endometriosis of the appendix is currently unknown. Since symptoms often overlap with those of acute appendicitis, endometriosis of the appendix presents a diagnostic challenge in the emergency department. This large retrospective study investigates the incidence and perioperative clinical, radiologic, and laboratory findings, as well as possible differences between patients with and without endometriosis. METHODS: Data from consecutive patients who underwent appendectomy for suspected appendicitis without a history of endometriosis were analyzed. Perioperative clinical, laboratory, perioperative, and histopathologic findings were compared between women with and without endometriosis. RESULTS: Between January 2008 and June 2023, 2484 consecutive patients without a history of endometriosis underwent urgent appendectomy for suspected appendicitis. Endometriosis was detected on histopathologic examination in 17 (0.7%) patients. Signs of appendicitis were found less frequently on ultrasound in the endometriosis group compared to the non-endometriosis group (23.4% vs. 61.5%; p = 0.002; OR = 0.193; 95% CI 0.063-0.593). There were no differences in physical examination findings, duration of symptoms, degree of inflammation, surgical outcomes, or complication rates. CONCLUSION: The incidence of endometriosis of the appendix in patients undergoing appendectomy for suspected appendicitis was higher than suggested by data from autopsy series and populations with biopsy-proven endometriosis. Patients with endometriosis of the appendix were less likely to have a positive ultrasound finding, but perioperative and histopathologic findings and severity of inflammation did not differ from patients without endometriosis, presenting diagnostic challenges for clinicians.


Assuntos
Apendicectomia , Apendicite , Endometriose , Humanos , Feminino , Endometriose/cirurgia , Endometriose/patologia , Apendicite/cirurgia , Apendicite/patologia , Estudos Retrospectivos , Adulto , Incidência , Pessoa de Meia-Idade , Adulto Jovem , Adolescente
4.
Environ Health ; 22(1): 51, 2023 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-37415220

RESUMO

INTRODUCTION: Exposure to nerve agents, pyridostigmine bromide (PB), pesticides, and oil-well fires during the 1991 Gulf War (GW) are major contributors to the etiology of Gulf War Illness (GWI). Since the apolipoprotein E (APOE) ε4 allele is associated with the risk of cognitive decline with age, particularly in the presence of environmental exposures, and cognitive impairment is one of the most common symptoms experienced by veterans with GWI, we examined whether the ε4 allele was associated with GWI. METHODS: Using a case-control design, we obtained data on APOE genotypes, demographics, and self-reported GW exposures and symptoms that were deposited in the Boston Biorepository and Integrative Network (BBRAIN) for veterans diagnosed with GWI (n = 220) and healthy GW control veterans (n = 131). Diagnosis of GWI was performed using the Kansas and/or Center for Disease Control (CDC) criteria. RESULTS: Age- and sex-adjusted analyses showed a significantly higher odds ratio for meeting the GWI case criteria in the presence of the ε4 allele (Odds ratio [OR] = 1.84, 95% confidence interval [CI = 1.07-3.15], p ≤ 0.05) and with two copies of the ε4 allele (OR = 1.99, 95% CI [1.23-3.21], p ≤ 0.01). Combined exposure to pesticides and PB pills (OR = 4.10 [2.12-7.91], p ≤ 0.05) as well as chemical alarms and PB pills (OR = 3.30 [1.56-6.97] p ≤ 0.05) during the war were also associated with a higher odds ratio for meeting GWI case criteria. There was also an interaction between the ε4 allele and exposure to oil well fires (OR = 2.46, 95% CI [1.07-5.62], p ≤ 0.05) among those who met the GWI case criteria. CONCLUSION: These findings suggest that the presence of the ε4 allele was associated with meeting the GWI case criteria. Gulf War veterans who reported exposure to oil well fires and have an ε4 allele were more likely to meet GWI case criteria. Long-term surveillance of veterans with GWI, particularly those with oil well fire exposure, is required to better assess the future risk of cognitive decline among this vulnerable population.


Assuntos
Apolipoproteínas E , Síndrome do Golfo Pérsico , Síndrome do Golfo Pérsico/genética , Humanos , Apolipoproteínas E/genética , Veteranos , Brometo de Piridostigmina/toxicidade , Praguicidas/toxicidade , Substâncias Perigosas/toxicidade , Masculino , Feminino , Pessoa de Meia-Idade , Fumaça/efeitos adversos
5.
Artigo em Inglês | MEDLINE | ID: mdl-37462295

RESUMO

BACKGROUND: PERSIST was a prospective, non-interventional, real-world study of guselkumab and ustekinumab in adult patients with moderate-to-severe plaque psoriasis in Germany. OBJECTIVES: To examine effectiveness, safety and quality-of-life (QoL) outcomes to Week (W) 104 of treatment with guselkumab and ustekinumab in patients with moderate-to-severe plaque psoriasis. METHODS: Patients (≥18 years of age) received guselkumab or ustekinumab as per routine clinical practice. Outcomes to W104 were examined separately in guselkumab and ustekinumab recipients. An ad hoc exploratory analysis of outcomes with guselkumab versus ustekinumab was also performed following propensity score matching. RESULTS: Overall, 302 and 313 patients received guselkumab and ustekinumab, respectively. Patients in both cohorts experienced improvements in disease activity and QoL that were maintained to W104, with 64.7% and 63.6% of guselkumab- and 54.6% and 64.4% of ustekinumab-treated patients achieving a Psoriasis Area and Severity Index (PASI) 90 response and a Dermatology Life Quality Index (DLQI) 0/1 score, respectively. Propensity score matching yielded well-balanced baseline characteristics except for prior biologic use, which was higher in guselkumab versus ustekinumab recipients (51.7% vs. 32.0%). Achievement of PASI ≤1 at W104 was more common in guselkumab versus ustekinumab recipients (58.7% vs. 49.7%). The W104 PASI90 response rate was 65.6% with guselkumab and 56.0% with ustekinumab; corresponding rates for PASI100 were 44.3% and 28.5%. In guselkumab recipients, response rates were higher in biologic-naïve versus biologic-experienced patients (PASI90, 77.1% vs. 53.4%; PASI100, 55.0% vs. 33.0%). A high level of response for QoL outcomes was observed for both treatments. CONCLUSIONS: Ustekinumab and guselkumab led to improvements in physician-assessed and patient-reported outcomes that were sustained for up to 2 years, with no new safety signals identified. Following propensity score matching, greater improvements in PASI outcomes were observed with guselkumab versus ustekinumab. Improvements with guselkumab were highest in biologic-naïve patients, highlighting the value of early treatment.

6.
Knee Surg Sports Traumatol Arthrosc ; 31(4): 1583-1592, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35994079

RESUMO

PURPOSE: This study aimed to identify and prevent preoperative factors that can be influenced in preoperative planning to reduce postoperative malcorrections. METHODS: The method used in this study was a retrospective two-centre analysis of 78 pre and postoperative fully weight-bearing radiographs of patients who underwent valgus osteotomy correction due to symptomatic medial compartment osteoarthritis. A computer software (TraumaCad®) was used to aim for an intersection point of the mechanical tibiofemoral axis (mTFA) with the tibia plateau at 55-60% (medial = 0%, lateral = 100%). Postoperative divergence ± 5% of this point was defined as over- and undercorrection. Preoperative joint geometry factors were correlated with postoperative malcorrection. Planning was conducted using the established method described by Miniaci (Group A) and with additional correction of the joint line convergence angle (JLCA) using the formula JLCA-2/2 (Group B). Additionally, in a small clinical case series, planning was conducted with JLCA correction. Statistical analysis was performed using (multiple) linear regression analysis and analysis of variance (ANOVA) with p < 0.05 considered significant. RESULTS: In 78 analysed cases, postoperative malcorrection was detected in 37.2% (5.1% undercorrection, 32.1% overcorrection). Linear regression analysis revealed preoperative body mass index (BMI, p = 0.04), JLCA (p = 0.0001), and osteotomy level divergence (p = 0.0005) as factors correlated with overcorrection. In a multiple regression analysis, JLCA and osteotomy level divergence remained significant factors. Preoperative JLCA correction reduced the planned osteotomy gap (A 9.7 ± 2.8 mm vs B 8.3 ± 2.4 mm; p > 0.05) and postoperative medial proximal tibial angle (MPTA: A 94.3 ± 2.1° vs B 92.3 ± 1.5°; p < .05) in patients with preoperative JLCA ≥ 4°. The results were validated using a virtual postoperative correction of cases with overcorrection. A case series (n = 8) with a preoperative JLCA > 4 revealed a postoperative accuracy using the JLCA correction of 3.4 ± 1.9%. CONCLUSION: Preoperative JLCA ≥ 4° and tibial osteotomy level divergence were identified as risk factors for postoperative overcorrection. Preoperative JLCA correction using the formula JLCA-2/2 is proposed to better control ideal postoperative correction and reduce MPTA. The intraoperatively realised osteotomy level should be precisely in accordance with preoperative planning. LEVEL OF EVIDENCE: III, cross-sectional study.


Assuntos
Osteoartrite do Joelho , Humanos , Estudos Retrospectivos , Osteoartrite do Joelho/cirurgia , Osteoartrite do Joelho/etiologia , Estudos Transversais , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/cirurgia , Tíbia/cirurgia , Osteotomia/métodos
7.
Conserv Biol ; 2022 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-35098582

RESUMO

An important rationale for legally-farmed and synthetic wildlife products are that they reduce illegal wild-sourced trade by supplying markets with sustainable alternatives. For this to work, more established illegal-product consumers must switch to legal alternatives than new legal-product consumers drawn to illegal wild products. Despite widespread debate on the magnitude and direction of switching, studies among actual consumers are lacking. We used an anonymous online survey of 1421 Traditional Chinese Medicine consumers in China to investigate switching between legal farmed, synthetic, and illegal wild bear bile. We examined past consumption behaviour, and applied a discrete choice experiment framed within worsening hypothetical disease scenarios, using latent class models to investigate groups with shared preferences. Bear bile consumers (86% respondents) were wealthier, more likely to have family who consumed bile, and less knowledgeable about bile treatments than non-consumers. Consumer preferences were heterogenous but most consumers preferred switching between bile types as disease worsened. We identified five distinct latent classes within our sample: 'law-abiding consumers' (34% respondents), who prefer legal products and were unlikely to switch; two 'all-natural consumer' groups (53%), who dislike synthetics but may switch between farmed and wild products; and two 'non-consumer' groups (12%) who prefer not to buy bile. People with past experience of bile consumption had different preferences than those without. Willingness to switch to wild products was related to believing they were legal, although the likelihood of switching was mediated by preferences for cheaper products sold in legal, familiar places. We show that consumers of wild bile may switch, given the availability of a range of legal alternatives, while legal-product consumers may switch to illegal products if the barriers to doing so are small. Understanding preferences that promote or impede switching should be a key consideration when attempting to predict consumer behaviour in complex wildlife markets. This article is protected by copyright. All rights reserved.


Wildlife consumer characteristics and preferences determine their likelihood and direction of switching between legal and illegal products.

8.
Climacteric ; 25(6): 615-621, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36218141

RESUMO

OBJECTIVE: Oral but not transdermal menopausal hormone therapy (MHT) increases the risk of venous thromboembolism. There is no evidence regarding the risk of the serious complication pulmonary embolism (PE). The aim was to investigate the risk of PE in women using MHT depending on administration route, type of progestin and treatment duration. METHOD: The population-based case-control study covered 1,771,253 women aged 40-69 years, during 2006-2015. Diagnoses of PE (n = 13,974) and drug dispensations were received from national validated registers. RESULTS: Current MHT users had a higher risk of PE than non-users (odds ratio [OR] 1.15, 95% confidence interval [CI] 1.05-1.26). First ever users had the highest risk (OR 2.07, 95% CI 1.23-3.50). Transdermal administration was not associated with increased risk of PE. The OR was slightly but non-significantly higher with estrogen combined with medroxyprogesterone acetate than with norethisterone acetate. DISCUSSION: The risk of PE was significantly increased in users of oral but not transdermal MHT, with the highest risk in first ever users of oral estrogen combined with medroxyprogesterone acetate. The risk was considerably lower in women with recurrent treatment, probably because of the healthy user effect. CONCLUSION: PE was most common close to initiation of oral treatment. Transdermal MHT did not increase the risk of PE.


Assuntos
Terapia de Reposição de Estrogênios , Embolia Pulmonar , Feminino , Humanos , Terapia de Reposição de Estrogênios/efeitos adversos , Acetato de Medroxiprogesterona , Estudos de Casos e Controles , Progestinas , Estrogênios , Administração Cutânea , Embolia Pulmonar/induzido quimicamente , Embolia Pulmonar/epidemiologia , Menopausa , Fatores de Risco
9.
J Eur Acad Dermatol Venereol ; 36(9): 1568-1577, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35569014

RESUMO

BACKGROUND: PERSIST was a prospective, non-interventional, long-term, German multicentre study of patients with moderate-to-severe psoriasis receiving guselkumab, an approved monoclonal antibody that binds to the p19 subunit of interleukin (IL)-23, in a real-world setting. OBJECTIVES: Evaluation of the efficacy and safety of guselkumab, and its effect on health-related quality of life (HRQoL), in patients with moderate-to-severe psoriasis who have received 52 weeks of treatment. METHODS: Patients (≥18 years old) were prescribed guselkumab as per routine clinical practice. End points assessed include Psoriasis Area and Severity Index (PASI), Physician's Global Assessment (PGA), target Nail Psoriasis Severity Index (NAPSI), and the Dermatology Life Quality Index (DLQI). RESULTS: Overall, 303 patients were enrolled and treated with guselkumab. Mean disease duration was 21.0 years, and 77.2% and 51.2% of patients had received ≥1 prior conventional systemic or ≥1 prior biologic therapy, respectively. Mean PASI score decreased from 16.4 at baseline to 3.0 by Week (W) 28, and further decreased to 2.4 by W52, while the proportion of patients achieving an absolute PASI score of ≤1 increased from 1.3% at baseline, to 50.8% at W28 and to 58.4% by W52. PASI90 and PASI100 responses also showed marked improvements between W28 and W52, regardless of biologic treatment history. Clearance of psoriatic skin was observed in difficult-to-treat areas, with the percentage of patients achieving a PGA score ≤1 increasing between W28 and W52. Guselkumab improved HRQoL; mean DLQI score decreased from 13.7 at baseline to 2.8 by W28, and further decreased to 2.4 by W52. At W52, 64.6% of patients achieved a DLQI score ≤1. The cumulative probability of drug survival was 92.4% at W52. CONCLUSIONS: Guselkumab is efficacious and well tolerated regardless of previous biologic therapies, comorbidities or psoriasis manifestation in difficult-to-treat areas. No new safety signals were observed.


Assuntos
Psoríase , Qualidade de Vida , Adulto , Humanos , Anticorpos Monoclonais Humanizados , Método Duplo-Cego , Interleucina-23 , Subunidade p19 da Interleucina-23/efeitos adversos , Subunidade p19 da Interleucina-23/uso terapêutico , Estudos Prospectivos , Psoríase/tratamento farmacológico , Índice de Gravidade de Doença , Resultado do Tratamento
10.
Nature ; 528(7581): 237-40, 2015 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-26659183

RESUMO

The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense.

11.
J Eur Acad Dermatol Venereol ; 35(3): 701-711, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32939860

RESUMO

BACKGROUND: Brodalumab is a fully human monoclonal immunoglobulin IgG2 antibody that binds to the human IL-17 receptor subunit A and by that inhibits the biologic action of IL-17A, IL-17F, IL-17C and IL-17E. Therapy with fumaric acid esters (FAE) is a well established and widely used first-line systemic treatment for subjects with moderate-to-severe plaque psoriasis. OBJECTIVES: To compare brodalumab to FAE in terms of clinical efficacy, patient-reported outcomes and safety in subjects with moderate-to-severe plaque psoriasis who were naïve to systemic treatment. METHODS: Eligible subjects were randomized 1 : 1 to 210 mg brodalumab injections or oral FAE according to product label in this 24-week, open-label, assessor-blinded, multi-centre, head-to-head phase 4 trial. The primary endpoints were having PASI75 and having sPGA score of 0 or 1 (sPGA 0/1). Subjects with missing values for the primary endpoints were considered non-responders. RESULTS: A total of 210 subjects were randomized. 91/105 subjects completed brodalumab treatment and 58/105 subjects completed FAE treatment. At Week 24, significantly more subjects in the brodalumab group compared to the FAE group had PASI75 (81.0% vs. 38.1%, P < 0.001) and sPGA 0/1 (64.8% vs. 20.0%, P < 0.001). In the brodalumab group, the median time to both PASI75 and to PASI90 was significantly shorter than in the FAE group (4.1 weeks vs. 16.4 weeks, and 7.4 weeks vs. 24.4 weeks, respectively, P < 0.0001 for both). The rate of adverse events was lower in subjects treated with brodalumab compared to subjects treated with FAE (616.4 vs. 1195.8 events per 100 exposure years). No new safety signals were detected for brodalumab. CONCLUSIONS: Brodalumab was associated with rapid and significant improvements in signs and symptoms of moderate-to-severe plaque psoriasis, with a superior efficacy profile to what was observed with FAE in systemic-naïve subjects over 24 weeks.


Assuntos
Fumaratos , Psoríase , Administração Oral , Adulto , Anticorpos Monoclonais Humanizados , Fumaratos/uso terapêutico , Humanos , Injeções Subcutâneas , Psoríase/tratamento farmacológico , Índice de Gravidade de Doença , Resultado do Tratamento
12.
Radiologe ; 61(6): 532-540, 2021 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-34061214

RESUMO

CLINICAL PROBLEM: Imaging plays a major role to differentiate interstitial edematous from necrotic pancreatitis and to describe relevant local complications for proper patient management and decision-making in acute pancreatitis. STANDARD RADIOLOGICAL PROCEDURES: The revised Atlanta classification 2012 of acute pancreatitis divides patients into mild, moderately severe and severe groups. Computed tomography (CT) and magnetic resonance imaging (MRI) are well established for diagnosis and follow-up of acute pancreatitis and its complications METHODOLOGICAL INNOVATIONS AND ASSESSMENT: Based on the revised Atlanta classification, CT and MRI allow for adequate categorization of interstitial edematous and necrotic pancreatitis. Imaging and standardized reporting nomenclature enable confident differentiation of early and late complications in acute pancreatitis. RECOMMENDATIONS: The aim of this review article is to present an image-rich overview of different morphologic characteristics of acute pancreatitis and associated local complications by CT or MRI using case examples.


Assuntos
Pancreatite , Doença Aguda , Humanos , Imageamento por Ressonância Magnética , Necrose , Pancreatite/diagnóstico por imagem , Tomografia Computadorizada por Raios X
13.
Eur J Orthop Surg Traumatol ; 31(7): 1427-1433, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33590317

RESUMO

PURPOSE: Instability of the posterior pelvic ring may be stabilized by lumbopelvic fixation. The optimal osseous corridor for iliac screw placement from the posterior superior iliac spine to the anterior inferior iliac spine requires multiple ap- and lateral-views with additional obturator-outlet and -inlet views. The purpose of this study was to determine if navigated iliac screw placement for lumbopelvic fixation influences surgical time, fluoroscopy time, radiation exposure, and complication rates. METHODS: Bilateral lumbopelvic fixation was performed in 63 patients. Implants were inserted as previously described by Schildhauer. A passive optoelectronic navigation system with surface matching on L4 was utilized for navigated iliac screw placement. To compare groups, demographics were assessed. Operative time, fluoroscopic time, and radiation were delineated. RESULTS: Conventional fluoroscopic imaging for lumbopelvic fixation was performed in 32 patients and 31 patients underwent the procedure with navigated iliac screw placement. No differences were found between the groups regarding demographics, comorbidities, or additional surgical procedures. Utilization of navigation led to fluoroscopy time reduction of more than 50% (3.2 vs. 8.6 min.; p < 0.001) resulting in reduced radiation (2004.5 vs. 5130.8 Gy*cm2; p < 0.001). Operative time was reduced in the navigation group (176.7 vs. 227.4 min; p = 0.002) despite the necessity of additional surface referencing. CONCLUSION: For iliac screws, identifying the correct entry point and angle of implantation requires detailed anatomic knowledge and multiple radiographic views. In our study, additional navigation reduced operative time and fluoroscopy time resulting in a significant reduction of radiation exposure for patients and OR personnel.


Assuntos
Fraturas da Coluna Vertebral , Cirurgia Assistida por Computador , Parafusos Ósseos , Fluoroscopia , Fixação Interna de Fraturas/efeitos adversos , Humanos , Ílio/cirurgia , Sacro/diagnóstico por imagem , Sacro/lesões , Sacro/cirurgia
14.
J Synchrotron Radiat ; 27(Pt 4): 890-901, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33565997

RESUMO

Experiments using a THz pump and an X-ray probe at an X-ray free-electron laser (XFEL) facility like the Linac Coherent Light Source II (LCLS II) require frequency-tunable (3 to 20 THz), narrow bandwidth (∼10%), carrier-envelope-phase-stable THz pulses that produce high fields (>1 MV cm-1) at the repetition rate of the X-rays and are well synchronized with them. In this paper, a two-bunch scheme to generate THz radiation at LCLS II is studied: the first bunch produces THz radiation in an electromagnet wiggler immediately following the LCLS II undulator that produces X-rays from the second bunch. The initial time delay between the two bunches is optimized to compensate for the path difference in THz transport. The two-bunch beam dynamics, the THz wiggler and radiation are described, as well as the transport system bringing the THz pulses from the wiggler to the experimental hall.

15.
Phys Rev Lett ; 124(5): 054801, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32083908

RESUMO

We present the first demonstration of THz driven bunch compression and timing stabilization of a relativistic electron beam. Quasi-single-cycle strong field THz radiation is used in a shorted parallel-plate structure to compress a few-fC beam with 2.5 MeV kinetic energy by a factor of 2.7, producing a 39 fs rms bunch length and a reduction in timing jitter by more than a factor of 2 to 31 fs rms. This THz driven technique offers a significant improvement to beam performance for applications like ultrafast electron diffraction, providing a critical step towards unprecedented timing resolution in ultrafast sciences, and other accelerator applications using femtosecond-scale electron beams.

16.
Graefes Arch Clin Exp Ophthalmol ; 258(1): 129-135, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31754827

RESUMO

PURPOSE: Visual acuity (VA) is an important determinant of visual function. Here we establish procedures and recommendations for VA testing extending beyond the classical VA and thus make them available for future studies of visual function in health and disease. Specifically, we provide reference values for photopic and scotopic conventional uncrowded visual acuity (cVA) and Vernier-hyperacuity (hVA) and assess their reproducibility and dependence on contrast polarity. METHODS: For ten observers with normal vision, we determined photopic ("p"; maximal luminance 220 cd/m2) and scotopic ("s"; maximal luminance 0.004 cd/m2; 40 min of dark adaptation) cVA and hVA, for two contrast polarities i.e. black optotypes on white background and vice versa. To assess intersession effects, two sets of measurements were obtained on different days. RESULTS: Compared to pcVA (1.32 decimal VA; - 0.12 ± 0.02 LogMAR), the phVA (14.45 decimal VA; - 1.16 ± 0.04 LogMAR) scaled (in terms of decimal visual acuity) on average with a factor 11.0, the scVA (0.12 decimal VA; 0.91 ± 0.03 LogMAR) with a factor of 0.1, and the shVA (1.47 decimal VA; - 0.17 ± 0.02 LogMAR) with a factor of 1.1. There were neither significant effects of contrast polarity (p > 0.12), nor of session (p > 0.28). CONCLUSIONS: Our approach optimises integrated photopic and scotopic cVA and hVA measurements for general use and thus encourages the integration of these important measures of scotopic visual function in future studies. The absence of strong intersession effects demonstrates that no dedicated training session is needed to obtain scotopic and hVA measurements. The combined measures of scotopic and photopic VAs open a field of applications to study interplay and plasticity of the retinal photoreceptor systems and cortical processing in health and visual disease. As a rule of thumb, hyperacuity is 10× higher both in the photopic and scotopic range than conventional acuity. Thus, scotopic hyperacuity is close to photopic conventional acuity.


Assuntos
Visão de Cores/fisiologia , Adaptação à Escuridão/fisiologia , Transtornos da Visão/diagnóstico , Acuidade Visual , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa , Reprodutibilidade dos Testes , Transtornos da Visão/fisiopatologia , Testes Visuais/métodos , Adulto Jovem
17.
Opt Express ; 27(21): 30340-30349, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31684282

RESUMO

We demonstrate a high repetition-rate, single-cycle THz source with a maximum average power of 1.35 mW, operating at a center frequency of 2 THz. This result was obtained by optical rectification (OR) in GaP using an amplifier-free, nonlinearly compressed modelocked thin-disk oscillator based on Yb:YAG, delivering 8.4 µJ pulses with 88 fs duration at a repetition rate of 13.4 MHz, resulting in driving pulses for OR with 112 W average power and 80 MW peak power. To the best of our knowledge, our result represents the highest average power so far achieved with OR in GaP. The demonstrated performance is very attractive for improving current linear THz time-domain spectroscopy experiments, which are currently restricted by low signal-to-noise ratio and long measurement times.

18.
Phys Rev Lett ; 122(10): 107202, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30932645

RESUMO

Using density functional theory and Monte Carlo calculations, we study the thickness dependence of the magnetic and electronic properties of a van der Waals interlayer antiferromagnet in the two-dimensional limit. Considering MnBi_{2}Te_{4} as a model material, we find it to demonstrate a remarkable set of thickness-dependent magnetic and topological transitions. While a single septuple layer block of MnBi_{2}Te_{4} is a topologically trivial ferromagnet, the thicker films made of an odd (even) number of blocks are uncompensated (compensated) interlayer antiferromagnets, which show wide band gap quantum anomalous Hall (zero plateau quantum anomalous Hall) states. Thus, MnBi_{2}Te_{4} is the first stoichiometric material predicted to realize the zero plateau quantum anomalous Hall state intrinsically. This state has been theoretically shown to host the exotic axion insulator phase.

19.
Diabet Med ; 36(5): 591-599, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30663133

RESUMO

AIM: To evaluate point-of-care-testing (POCT) for the diagnosis of Type 2 diabetes mellitus 6-12 weeks post-partum in women with gestational diabetes (GDM). METHODS: Post-partum glucose assessment (75-mg oral glucose tolerance test, OGTT) was performed prospectively in 122 women with GDM (1 November 2015 to 1 November 2017) at Tygerberg Hospital, Cape Town, South Africa. Individuals with known pre-existing diabetes were excluded. The accuracy and clinical utility of POCT (capillary finger-prick) were compared with laboratory plasma glucose (hexokinase and glucokinase methods). The OGTT consisted of two time points (fasting and 2 h) during which concurrent glucose samples (POCT and laboratory) were obtained. Bland-Altman plots and paired analysis were used to assess the analytical accuracy of POCT, whereas its diagnostic performance was determined using positive and negative predictive values to calculate specificity and sensitivity. RESULTS: Spearman's ranked correlation analysis indicated a strong association between POCT and laboratory glucose values at both OGTT time points (fasting, r = 0.95, P < 0.0001; 2 h, r = 0.88, P < 0.0001). Thirty-six women were diagnosed with Type 2 diabetes based on gold standard laboratory glucose levels (fasting > 7 mmol/l; 2 h > 11.1 mmol/l). POCT correctly identified Type 2 diabetes in 78% of women (28 of 36) with a positive predictive value of 89.3% and a negative predictive value of 96.7% at the fasting time point. The sensitivity and specificity of POCT to diagnose Type 2 diabetes were 89% (fasting), 85.7% (2 h) and 96.7% (fasting), 98.5% (2 h) respectively. POCT proved less sensitive to diagnose pre-diabetes (69%) but displayed satisfactory specificity (92%) at both time points assessed. CONCLUSION: POCT accurately identifies women with Type 2 diabetes 6-12 weeks after GDM.


Assuntos
Análise Química do Sangue/métodos , Glicemia/análise , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Gestacional , Testes Imediatos , Transtornos Puerperais/diagnóstico , Adulto , Coleta de Amostras Sanguíneas , Diabetes Mellitus Tipo 2/sangue , Diabetes Gestacional/sangue , Diabetes Gestacional/diagnóstico , Feminino , Teste de Tolerância a Glucose , Humanos , Período Pós-Parto/sangue , Gravidez , Transtornos Puerperais/sangue , África do Sul , Fatores de Tempo , Veias/química , Adulto Jovem
20.
J Exp Child Psychol ; 183: 19-32, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30851626

RESUMO

Reaching to target locations on the body has been studied little despite its importance for adaptive behaviors such as feeding, grooming, and indicating a source of discomfort. This behavior requires multisensory integration given that it involves coordination of touch, proprioception, and sometimes vision as well as action. Here we examined the origins of this skill by investigating how infants begin to localize targets on the body and the motor strategies by which they do so. Infants (7-21 months of age) were prompted to reach to a vibrating target placed at five arm/hand locations (elbow, crook of elbow, forearm, palm, and top of hand) one by one. To manually localize the target, infants needed to reach with one arm to the other. Results suggest that coordination increases with age in the strategies that infants used to localize body targets. Most infants showed bimanual coordination and usually moved the target arm toward the reaching arm to assist reaching. Furthermore, intersensory coordination increased with age. Simultaneous movements of the two arms increased with age, as did coordination between vision and reaching. The results provide new information about the development of multisensory integration during tactile localization and how such integration is linked to action.


Assuntos
Desenvolvimento Infantil/fisiologia , Propriocepção/fisiologia , Desempenho Psicomotor/fisiologia , Percepção do Tato/fisiologia , Tato/fisiologia , Feminino , Humanos , Lactente , Masculino , Movimento/fisiologia
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