Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 527
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Nature ; 557(7703): 76-80, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29720633

RESUMO

As conventional electronics approaches its limits 1 , nanoscience has urgently sought methods of fast control of electrons at the fundamental quantum level 2 . Lightwave electronics 3 -the foundation of attosecond science 4 -uses the oscillating carrier wave of intense light pulses to control the translational motion of the electron's charge faster than a single cycle of light5-15. Despite being particularly promising information carriers, the internal quantum attributes of spin 16 and valley pseudospin17-21 have not been switchable on the subcycle scale. Here we demonstrate lightwave-driven changes of the valley pseudospin and introduce distinct signatures in the optical readout. Photogenerated electron-hole pairs in a monolayer of tungsten diselenide are accelerated and collided by a strong lightwave. The emergence of high-odd-order sidebands and anomalous changes in their polarization direction directly attest to the ultrafast pseudospin dynamics. Quantitative computations combining density functional theory with a non-perturbative quantum many-body approach assign the polarization of the sidebands to a lightwave-induced change of the valley pseudospin and confirm that the process is coherent and adiabatic. Our work opens the door to systematic valleytronic logic at optical clock rates.

2.
Philos Trans A Math Phys Eng Sci ; 380(2217): 20200321, 2022 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-34974721

RESUMO

Structure formation during solidification of a Pd-Ni-Cu-P melt is studied. It is demonstrated that changes in the heat transfer conditions lead to a nonlinear change in the characteristics of the structure. The article presents the regimes of cooling the samples and the results of their structure and composition studies. It is found that a decrease in the cooling rate of the alloy leads to an increase in the size, proportion and composition of nanoinclusions in an amorphous matrix. X-ray diffraction method, electron probe microanalysis, transmission microscopy and scanning calorimetry are used for samples characterization. This article is part of the theme issue 'Transport phenomena in complex systems (part 2)'.

3.
Nature ; 533(7602): 225-9, 2016 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-27172045

RESUMO

Ever since Ernest Rutherford scattered α-particles from gold foils, collision experiments have revealed insights into atoms, nuclei and elementary particles. In solids, many-body correlations lead to characteristic resonances--called quasiparticles--such as excitons, dropletons, polarons and Cooper pairs. The structure and dynamics of quasiparticles are important because they define macroscopic phenomena such as Mott insulating states, spontaneous spin- and charge-order, and high-temperature superconductivity. However, the extremely short lifetimes of these entities make practical implementations of a suitable collider challenging. Here we exploit lightwave-driven charge transport, the foundation of attosecond science, to explore ultrafast quasiparticle collisions directly in the time domain: a femtosecond optical pulse creates excitonic electron-hole pairs in the layered dichalcogenide tungsten diselenide while a strong terahertz field accelerates and collides the electrons with the holes. The underlying dynamics of the wave packets, including collision, pair annihilation, quantum interference and dephasing, are detected as light emission in high-order spectral sidebands of the optical excitation. A full quantum theory explains our observations microscopically. This approach enables collision experiments with various complex quasiparticles and suggests a promising new way of generating sub-femtosecond pulses.

4.
Nature ; 523(7562): 572-5, 2015 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-26223624

RESUMO

Acceleration and collision of particles has been a key strategy for exploring the texture of matter. Strong light waves can control and recollide electronic wavepackets, generating high-harmonic radiation that encodes the structure and dynamics of atoms and molecules and lays the foundations of attosecond science. The recent discovery of high-harmonic generation in bulk solids combines the idea of ultrafast acceleration with complex condensed matter systems, and provides hope for compact solid-state attosecond sources and electronics at optical frequencies. Yet the underlying quantum motion has not so far been observable in real time. Here we study high-harmonic generation in a bulk solid directly in the time domain, and reveal a new kind of strong-field excitation in the crystal. Unlike established atomic sources, our solid emits high-harmonic radiation as a sequence of subcycle bursts that coincide temporally with the field crests of one polarity of the driving terahertz waveform. We show that these features are characteristic of a non-perturbative quantum interference process that involves electrons from multiple valence bands. These results identify key mechanisms for future solid-state attosecond sources and next-generation light-wave electronics. The new quantum interference process justifies the hope for all-optical band-structure reconstruction and lays the foundation for possible quantum logic operations at optical clock rates.

5.
Tech Coloproctol ; 25(7): 849-855, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33978860

RESUMO

BACKGROUND: Fecal incontinence is a multifactorial problem and its etiology is complex. Various therapies are available and different success rates have been described. The aim of this study was to assess the effectiveness and safety of non-dynamic graciloplasty in patients with passive fecal incontinence. METHODS: We retrospectively studied charts of patients with fecal incontinence treated with graciloplasty at our institution from November 2015 until June 2018. Patients were included according to the following criteria: (1) presence of predominantly passive fecal incontinence and (2) presence of a lax perineal body. Primary outcome was the effectiveness, defined as a significant reduction or absence of the complaints of passive fecal incontinence at 3, 6 and 12 months after surgery. Second, we studied the safety of the procedure evaluating the complications within 30 days after surgery. RESULTS: Thirty-one patients met the inclusion criteria. Twenty-six of them, in addition to passive incontinence as the main symptom, had some degree of fecal urgency. The median age at the first visit to the outpatient clinic was 64.0 years (IQR 52-68). Most patients were female (n = 29, 94%). At 3 months after graciloplasty, 71% (22 of 31) of patients were successfully treated for their passive fecal incontinence. At 6 months, the success rate of the graciloplasty increased to 77%. At 12 months among the patients who were still seen in the clinic, the success rate was 58% (18/31). Two patients cancelled follow-up visits after 3 months, because of failure to control symptoms in 1 case. After 6 months, 9 patients were given the choice to do telephone follow-up only. Of these 11 patients without in-person follow-up, 10 were contacted 1 year after surgery and in 7 of them, the graciloplasty was effective in controlling their passive fecal incontinence for an overall success rate of 80% (25/31). Of the 26 patients with mixed passive and urge incontinence, 6 (23%) still complained of urge incontinence at 1 year. Of these patients with persistent urge incontinence, 6 underwent sacral nerve stimulation which was successful in 4. Two serious complications occurred within 30 days. A rectal perforation requiring temporary colostomy and a recto-vaginal fistula which was successfully repaired. CONCLUSION: Non-dynamic graciloplasty is an effective treatment for passive fecal incontinence. Differentiation based on subtypes of fecal incontinence might be important for a pattern-specific approach to treatment. More research is necessary to determine the right indications for more invasive treatments of fecal incontinence.


Assuntos
Procedimentos Cirúrgicos do Sistema Digestório , Terapia por Estimulação Elétrica , Incontinência Fecal , Doenças Retais , Canal Anal/cirurgia , Incontinência Fecal/etiologia , Incontinência Fecal/cirurgia , Feminino , Humanos , Estudos Retrospectivos , Resultado do Tratamento
6.
Nature ; 506(7489): 471-5, 2014 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-24572422

RESUMO

Interacting many-body systems are characterized by stable configurations of objects--ranging from elementary particles to cosmological formations--that also act as building blocks for more complicated structures. It is often possible to incorporate interactions in theoretical treatments of crystalline solids by introducing suitable quasiparticles that have an effective mass, spin or charge which in turn affects the material's conductivity, optical response or phase transitions. Additional quasiparticle interactions may also create strongly correlated configurations yielding new macroscopic phenomena, such as the emergence of a Mott insulator, superconductivity or the pseudogap phase of high-temperature superconductors. In semiconductors, a conduction-band electron attracts a valence-band hole (electronic vacancy) to create a bound pair, known as an exciton, which is yet another quasiparticle. Two excitons may also bind together to give molecules, often referred to as biexcitons, and even polyexcitons may exist. In indirect-gap semiconductors such as germanium or silicon, a thermodynamic phase transition may produce electron-hole droplets whose diameter can approach the micrometre range. In direct-gap semiconductors such as gallium arsenide, the exciton lifetime is too short for such a thermodynamic process. Instead, different quasiparticle configurations are stabilized dominantly by many-body interactions, not by thermalization. The resulting non-equilibrium quantum kinetics is so complicated that stable aggregates containing three or more Coulomb-correlated electron-hole pairs remain mostly unexplored. Here we study such complex aggregates and identify a new stable configuration of charged particles that we call a quantum droplet. This configuration exists in a plasma and exhibits quantization owing to its small size. It is charge neutral and contains a small number of particles with a pair-correlation function that is characteristic of a liquid. We present experimental and theoretical evidence for the existence of quantum droplets in an electron-hole plasma created in a gallium arsenide quantum well by ultrashort optical pulses.

7.
World J Surg ; 44(10): 3199-3206, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32794035

RESUMO

INTRODUCTION: Since the outbreak of COVID-19, measures were taken to protect healthcare staff from infection, to prevent infection of patients admitted to the hospital and to distribute PPE according to need. To assure the proper protection without overuse of limited supply of these equipments, screening of patients before surgical or diagnostic procedure was implemented. This study evaluates the results of this screening. METHOD: All patients screened for COVID-19 before procedure warranting either general, locoregional anaesthesia or sedation were included. Screening included a symptom questionnaire by phone, PCR and HRCT chest testing. Surgical or procedural details were registered together with actions taken based on screening results. RESULTS: Three hundred ninety-eight screenings were performed on 386 patients. The symptom questionnaire was completed in 72% of screenings. In 371 screenings, PCR testing was performed and negative. HRCT chest found 18 cases where COVID-19 could not be excluded, with negative PCR testing. Three patients had their surgery postponed due to inconclusive screening, and additional measures were taken in three other patients. There were incidental findings in 14% of HRCT chest scans. DISCUSSION: Pre-operative screening will differentiate if PPE is needed for procedures and which patients can safely have elective surgery during this COVID-19 pandemic and in the times to come. HRCT chest has no additional value in the pre-operative screening of asymptomatic patients. Screening can be performed with a symptom questionnaire, and additional screening with PCR testing in high-risk patient groups should be considered.


Assuntos
Infecções Assintomáticas , Betacoronavirus , Técnicas de Laboratório Clínico/métodos , Infecções por Coronavirus/diagnóstico , Testes Diagnósticos de Rotina , Procedimentos Cirúrgicos Eletivos , Programas de Rastreamento/métodos , Pneumonia Viral/diagnóstico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Betacoronavirus/isolamento & purificação , COVID-19 , Teste para COVID-19 , Criança , Pré-Escolar , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/transmissão , Feminino , Humanos , Controle de Infecções/instrumentação , Controle de Infecções/métodos , Transmissão de Doença Infecciosa do Paciente para o Profissional/prevenção & controle , Masculino , Pessoa de Meia-Idade , Pandemias/prevenção & controle , Equipamento de Proteção Individual , Pneumonia Viral/prevenção & controle , Pneumonia Viral/transmissão , SARS-CoV-2 , Adulto Jovem
8.
Anaesthesist ; 69(7): 453-462, 2020 07.
Artigo em Alemão | MEDLINE | ID: mdl-32346776

RESUMO

BACKGROUND: The climate crisis is the most serious threat to global health in the twenty-first century. In western countries 5-10% of all greenhouse gas emissions originate from the healthcare sector and the main contributing factors are energy-intense departments (intensive care units, operating suits and prehospital emergency services). OBJECTIVE: The aim of this review is to provide background knowledge and practical ideas to achieve climate-neutral hospitals. MATERIAL AND METHODS: Narrative review with information on the topics of (I) volatile anesthetics as greenhouse gases, (II) energy supply in hospitals and (III) solid waste management. RESULTS AND CONCLUSION: (I) Volatile anesthetics are highly potent greenhouse gases, especially desflurane has a major global warming potential. Total intravenous anesthesia (TIVA) with propofol or regional anesthetic techniques have a much lower impact on the climate. (II) Using sustainable energy sources as well as initiating energy sparing techniques, such as light-emitting diodes (LED) and motion sensors, can reduce CO2 emissions. (III) Waste can be managed by the reduce, reuse, recycle, rethink and research concept. Doctors should actively contribute to reach the climate goals.


Assuntos
Anestesiologia/tendências , Mudança Climática , Anestesia , Anestésicos Inalatórios/uso terapêutico , Dióxido de Carbono , Aquecimento Global , Gases de Efeito Estufa , Humanos , Energia Renovável , Gerenciamento de Resíduos
9.
Rep Prog Phys ; 82(6): 064401, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30991367

RESUMO

There are currently intense efforts being directed towards extending the range and energy of long distance nonlinear pulse propagation in the atmosphere by moving to longer infrared wavelengths, with the purpose of mitigating the effects of turbulence. In addition, picosecond and longer pulse durations are being used to increase the pulse energy. While both of these tacks promise improvements in applications, such as remote sensing and directed energy, they open up fundamental issues regarding the standard model used to calculate the nonlinear optical properties of dilute gases. Amongst these issues is that for longer wavelengths and longer pulse durations, exponential growth of the laser-generated electron density, the so-called avalanche ionization, can limit the propagation range via nonlinear absorption and plasma defocusing. It is therefore important for the continued development of the field to assess the theory and role of avalanche ionization in gases for longer wavelengths. Here, after an overview of the standard model, we present a microscopically motivated approach for the analysis of avalanche ionization in gases that extends beyond the standard model and we contend is key for deepening our understanding of long distance propagation at long infrared wavelengths. Our new approach involves the mean electron kinetic energy, the plasma temperature, and the free electron density as dynamic variables. The rate of avalanche ionization is shown to depend on the full time history of the pulsed excitation, as opposed to the standard model in which the rate is proportional to the instantaneous intensity. Furthermore, the new approach has the added benefit that it is no more computationally intensive than the standard one. The resulting memory effects and some of their measurable physical consequences are demonstrated for the example of long-wavelength infrared avalanche ionization and long distance high-intensity pulse propagation in air. Our hope is that this report in progress will stimulate further discussion that will elucidate the physics and simulation of avalanche ionization at long infrared wavelengths and advance the field.

10.
Opt Express ; 27(4): 5368-5382, 2019 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-30876142

RESUMO

Microscopic many-body theory coupled with Maxwell's equation is used to study dual-wavelength operation in vertical external-cavity surface-emitting lasers. The intrinsically dynamic nature of coexisting emission wavelengths in semiconductor lasers is associated with characteristic non-equilibrium carrier dynamics, which causes significant deformations of the quasi-equilibrium gain and carrier inversion. Extended numerical simulations are employed to efficiently investigate the parameter space to identify the regime for dual-wavelength operation. Using a frequency selective intracavity etalon, two families of modes are stabilized with dynamical interchange of the strongest emission peaks. For this operation mode, anti-correlated intensity noise is observed in agreement with the experiment. A method using effective frequency selective filtering is suggested for stabilization of genuine dual-wavelength output.

11.
Opt Express ; 27(21): 30462-30472, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31684294

RESUMO

The nonlinear optical response of GaAs is studied using extremely nonresonant 10 µm laser pulses with peak intensities greater than 2 GW/cm 2. We observe over an order of magnitude enhancement in the four-wave mixing efficiency by decreasing the CO 2 laser beat-wave frequency. This enhancement is attributed to currents of photoexcited unbound carriers modulated at the beat frequency, confirmed by measurements of nonlinear absorption at this long wavelength as well as a fully microscopic analysis of the excitation dynamics. Modeling of such nonperturbative semiconductor-laser interactions predicts that further decreasing the beat frequency can increase the nonlinear response and allow for its control over two orders of magnitude.

12.
Phys Rev Lett ; 123(22): 226601, 2019 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-31868400

RESUMO

Although a resistivity saturation (minimum conductivity) is often observed in disordered metallic solids, such phenomena in the corresponding liquids are not known. Here we report a saturation of the electrical resistivity in Zr_{64}Ni_{36} and Cu_{50}Zr_{50} liquids above a dynamical crossover temperature for the viscosity (T_{A}). The measurements were made for the levitated liquids under the microgravity conditions of the International Space Station. Based on recent molecular dynamics simulations, the saturation is likely due to the ineffectiveness of electron-phonon scattering above T_{A} when the phonon lifetime becomes too short compared to the electron relaxation time. This is different from the conventional resistivity saturation mechanisms in solids.

13.
Tech Coloproctol ; 23(11): 1065-1072, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31720908

RESUMO

BACKGROUND: Rectal prolapse is a disease presentation with a prevalence of about 1%, mainly affecting older women. It usually presents with symptoms of rectal mass, rectal bleeding, fecal incontinence or constipation, with patients frequently feeling socially isolated as a result. Perineal rectosigmoidectomy is associated with lesser morbidity and mortality than the abdominal procedure, but with a much higher recurrence rate. Therefore, this technique is mainly suitable for the frail elderly patient. Specific outcomes in an elderly population have been described in only a few studies. We evaluated the morbidity, mortality, recurrence rate and functional results after this procedure related to age. METHODS: All patients who underwent a perineal rectosigmoidectomy over a 10-year period in two tertiary referral centers were included in the study. American Society of Anesthesiology (ASA) grade, pre- and postoperative symptoms, pathology-reported post-fixation specimen length, length of in-patient stay, 30-day morbidity/mortality, and recurrence were measured. RESULTS: A total of 45 patients underwent a perineal rectosigmoidectomy. Forty-three (95%) were female, with a median age of 82.0 years (IQR 70.5-86.5), ASA grade III and median follow-up of 20 months (range 8.5-45.5 months). Half of the cohort was over 80 years old. Significant symptomatic relief was achieved, predominantly the resolution of rectal mass (8.9% vs. 60.0% preoperatively), fecal incontinence (15.6% vs. 46.7%) and constipation (4.4% vs. 26.7%). The median length of stay was 6 days, while morbidity occurred in 14 patients (31.1%) and recurrence occurred in 6 patients (13%). There were no deaths within 30 days of the procedure and outcomes were comparable in the < 80 and ≥ 80 age group. CONCLUSIONS: Perineal rectosigmoidectomy is safe for older patients with greater comorbidities resulting in good functional results and is associated with low morbidity and mortality.


Assuntos
Colo Sigmoide/cirurgia , Protectomia/efeitos adversos , Protectomia/métodos , Prolapso Retal/cirurgia , Idoso , Idoso de 80 Anos ou mais , Constipação Intestinal/etiologia , Incontinência Fecal/etiologia , Feminino , Idoso Fragilizado , Nível de Saúde , Humanos , Tempo de Internação , Masculino , Períneo , Prolapso Retal/complicações , Recidiva , Avaliação de Sintomas , Centros de Atenção Terciária , Resultado do Tratamento , Reino Unido
14.
Allergy ; 73(11): 2205-2213, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29672867

RESUMO

BACKGROUND: The skin of atopic dermatitis (AD) patients presents a significant dysbalance of the microbiome with a high colonization by Staphylococcus aureus (S. aureus), which positively correlates with the severity of the disease. OBJECTIVE: Understanding the role of epidermal dendritic cells (DC) as link between the innate and the adaptive immune systems in AD. METHODS: Comparative phenotypic and functional analysis of TLR2 on Langerhans cells (LC) and inflammatory dendritic epidermal cells (IDEC) in organotypic models as well as freshly isolated cells from healthy and AD skin. RESULTS: In situ analysis of freshly isolated LC and IDEC from AD skin revealed decreased TLR2 expression compared to LC from healthy skin. In contrast to IDEC, LC from AD skin failed to display any evidence for in situ activation. Exposure to TLR2 ligand Pam3Cys resulted in maturation and increased migratory activity of LC from normal skin. LC and IDEC from AD were unresponsive to TLR2 ligand in that they failed to mature and displayed a high spontaneous migratory activity. Keratinocytes from both healthy and AD skin expressed similar levels of TLR2. The production of IL-6 and IL-10 was impaired by Pam3Cys in supernatants from AD skin. IL-18 was significantly higher in supernatants from AD skin and not influenced by TLR2 ligation, when compared to healthy skin. CONCLUSION: Our results suggest that TLR2-mediated sensing of S. aureus-derived signals is strongly impaired in LC from AD skin. This phenomenon may partly contribute to the immune deviation in AD and the lack of S. aureus clearance.


Assuntos
Dermatite Atópica/imunologia , Dermatite Atópica/metabolismo , Tolerância Imunológica , Células de Langerhans/imunologia , Células de Langerhans/metabolismo , Receptor 2 Toll-Like/metabolismo , Imunidade Adaptativa , Biomarcadores , Movimento Celular/imunologia , Citocinas/metabolismo , Dermatite Atópica/patologia , Feminino , Expressão Gênica , Humanos , Imunidade Inata , Imunoglobulina E/sangue , Imunoglobulina E/imunologia , Imunofenotipagem , Queratinócitos/metabolismo , Masculino , Ligação Proteica , Índice de Gravidade de Doença , Staphylococcus aureus/imunologia , Receptor 2 Toll-Like/genética
15.
Phys Rev Lett ; 118(6): 063901, 2017 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-28234538

RESUMO

We simulate and elucidate the self-channeling of high-power 10 µm infrared pulses in atomic gases. The major new result is that the peak intensity can remain remarkably stable over many Rayleigh ranges. This arises from the balance between the self-focusing, diffraction, and defocusing caused by the excitation induced dephasing due to many-body Coulomb effects that enhance the low-intensity plasma densities. This new paradigm removes the Rayleigh range limit for sources in the 8-12 µm atmospheric transmission window and enables transport of individual multi-TW pulses over multiple kilometer ranges.

16.
Allergy ; 72(11): 1686-1693, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28376268

RESUMO

BACKGROUND: Aryl hydrocarbon receptor (AhR), an important regulator of immune responses, is activated by UVB irradiation in the skin. Langerhans cells (LC) in the epidermis of patients with atopic dermatitis (AD) carry the high-affinity receptor for IgE, FcεRI, and are crucially involved in the pathogenesis of AD by inducing inflammatory responses and regulating tolerogenic processes. OBJECTIVES: We investigated AhR and AhR repressor (AhRR) expression and functional consequences of AhR activation in human ex vivo skin cells and in in vitro-generated LC. METHODS: Epidermal cells from healthy skin were analyzed for their expression of AhR and AhRR. LC generated from CD34+ hematopoietic stem cells (CD34LC) were treated with the UV photoproduct and AhR ligand 6-formylindolo[3,2-b]carbazole (FICZ). Cell surface receptors, transcription factors, and the tolerogenic tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) were analyzed using flow cytometry and quantitative PCR. RESULTS: Epidermal LC and CD34LC express AhR and AhRR. AhR was also found in keratinocytes, which lack AhRR. AhR activation of LC by FICZ caused downregulation of FcεRI in CD34LC without affecting their maturation. AhR-mediated regulation of FcεRI did not involve any known transcription factors related to this receptor. Furthermore, we could show upregulation of IDO mediated by AhR engagement. CONCLUSIONS: Our study shows that AhR activation by FICZ reduces FcεRI and upregulates IDO expression in LC. This AhR-mediated anti-inflammatory feedback mechanism may dampen the allergen-induced inflammation in AD.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/fisiologia , Dermatite Atópica/imunologia , Retroalimentação Fisiológica/fisiologia , Inflamação/imunologia , Células de Langerhans/metabolismo , Receptores de Hidrocarboneto Arílico/fisiologia , Adulto , Feminino , Humanos , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Masculino , Pessoa de Meia-Idade , Receptores de IgE/metabolismo , Proteínas Repressoras/metabolismo
17.
J Microsc ; 268(3): 259-268, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28960298

RESUMO

The atomic structure of (GaIn)As/Ga(AsSb)/(GaIn)As-'W'-type quantum well heterostructures ('W'-QWHs) is investigated by scanning transmission electron microscopy (STEM). These structures were grown by metal organic vapour phase epitaxy and are built for type-II laser systems in the infrared wavelength regime. For two samples grown at 525°C and 550°C, intensity profiles are extracted from the STEM images for each sublattice separately. These intensity profiles are compared to the one obtained from an image simulation of an ideal 'W'-QWH that is modelled in close agreement with the experiment. From the intensity profiles, the width of the different quantum wells (QWs) can be determined. Additionally, characteristics connected to the growth of the structures, such as segregation coefficients and material homogeneity, are calculated. Finally, composition profiles are derived from the STEM intensity profiles to a first approximation. For these composition profiles, the expected photoluminescence (PL) is computed based using the semiconductor luminescence equations. The PL spectra are then compared to experimental measurements for both samples.

18.
J Eur Acad Dermatol Venereol ; 30(7): 1165-70, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26333514

RESUMO

BACKGROUND: Psoriasis is a chronic skin disease with deregulation of proteins in the immune system. These proteins include members of the heterogeneous S100 family, which have been discussed as potential biomarkers for disease severity. OBJECTIVE: The aim of this study was to evaluate the impact of S100A7, S100A8, S100A9 and S100A12 as possible markers for disease activity in patients with psoriasis skin disease. PATIENTS AND METHODS: S100A7, S100A8, S100A9 and S100A12 mRNA expression was determined in the skin of patients with psoriasis and controls (N = 341) by gene expression analyses. In addition, S100 serum levels were investigated by ELISA in an independent cohort of psoriasis patients (i) untreated, with different manifestations (skin/joints), (ii) under treatment (etanercept) and (iii) healthy controls, (N = 55). RESULTS: All S100-subtypes included are significantly upregulated in psoriasis skin lesions when compared with atopic dermatitis, lichen ruber and healthy donors. In untreated psoriasis patients, S100A12-serum levels showed the closest association with disease activity (PASI) (r = 0.542; P < 0.01). Serum levels decreased under treatment with etanercept (P < 0.05). CONCLUSION: Among the investigated S100-proteins, S100A12 showed the closest association with disease activity and therapeutic response and might therefore provide a valuable biomarker for psoriasis.


Assuntos
Biomarcadores/metabolismo , Psoríase/metabolismo , Proteína S100A12/metabolismo , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
19.
Klin Monbl Augenheilkd ; 233(4): 448-52, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27116506

RESUMO

BACKGROUND: "Retinitis pigmentosa" refers to a group of degenerative eye diseases with a genetic background. Flammer syndrome encompasses a set of symptoms and signs, mainly but not exclusively related to dysregulation of blood vessels. The purpose of the present study was to determine, with the help of a questionnaire, whether symptoms of Flammer syndrome occur more often in patients with retinitis pigmentosa than in controls. METHODS: 76 patients with retinitis pigmentosa (members of the Swiss patient organization for retinitis pigmentosa) and 274 control subjects answered a questionnaire (Flammer Syndrome Questionnaire) on 15 symptoms and signs of Flammer syndrome. RESULTS: Seven of 15 symptoms and signs of Flammer syndrome were significantly more often positive in retinitis pigmentosa patients than in controls. Six additional symptoms and signs occurred non-significantly more often and 2 non-significantly less often in patients with retinitis pigmentosa. CONCLUSION: Retinitis pigmentosa patients suffer significantly more often from symptoms and signs of the Flammer syndrome than control subjects. This includes low body mass index, low blood pressure, feeling cold, migraine, increased smell perception and perfectionism. The reason for this association between retinitis pigmentosa and Flammer syndrome and the potential implications need to be determined.


Assuntos
Doenças Vasculares Periféricas/epidemiologia , Retinose Pigmentar/epidemiologia , Transtornos de Sensação/epidemiologia , Adulto , Idoso , Causalidade , Comorbidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Vasculares Periféricas/diagnóstico , Prevalência , Retinose Pigmentar/diagnóstico , Fatores de Risco , Transtornos de Sensação/diagnóstico , Suíça/epidemiologia , Síndrome
20.
Clin Exp Allergy ; 45(8): 1356-66, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25640055

RESUMO

BACKGROUND: NFATc1 isoforms are highly regulated in peripheral T cells where they contribute to the effector function and cell homeostasis. OBJECTIVE: Here, we investigated the role of NFATc1 in asthma and in T cells. METHODS: In a murine model of allergic asthma, we analysed differences in T-cell development in this allergic disease model, between wild-type and NFATc1 conditional knockout mice. Thus, we performed quantitative real-time PCR to investigate the mRNA expression of Th2-associated genes as well as genes that are involved in IgE immunoglobulin class-switch. Additionally, we used ELISA, Western blot and flow cytometry (FACS) to analyse protein concentrations of Th1-, Th2- and Th17-specific transcription factors and cytokines and the Th2 chemokine, thymus and activation-regulated chemokine/chemokine ligand 17 (TARC/CCL17) by ELISA. RESULTS: Mice lacking NFATc1 in CD4(+) T cells display a significant reduction in lung Th2 and Th17 as well as an increase of Th1 cells in an experimental asthma model. Additionally, Batf gene, a recently described transcription factor of the Th2 and Th17 cell differentiation as well as a key T and B transcription factor involved in the IgE immunoglobulin class-switch, was found decreased in the lungs of these mice. As a consequence, serum OVA-specific IgE and IgG1 levels were found significantly decreased after allergen exposure and in the absence of NFATc1 in T cells in experimental allergic asthma. CONCLUSIONS AND CLINICAL RELEVANCE: Targeting NFATc1 in T lymphocytes ameliorated the allergic trait in the airways of NFATc1(fl/fl) xCD4Cre mice. NFATc1 emerges as a novel target for anti-allergy intervention.


Assuntos
Asma/imunologia , Deleção de Genes , Fatores de Transcrição NFATC/imunologia , Locos de Características Quantitativas/imunologia , Células Th17/imunologia , Células Th2/imunologia , Animais , Asma/genética , Quimiocina CCL17/genética , Quimiocina CCL17/metabolismo , Modelos Animais de Doenças , Imunoglobulina E/genética , Imunoglobulina E/imunologia , Imunoglobulina G/genética , Imunoglobulina G/imunologia , Camundongos , Camundongos Transgênicos , Fatores de Transcrição NFATC/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA