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1.
Clin Transplant ; 38(6): e15365, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38804605

RESUMEN

BACKGROUND: In May 2019, liver transplant (LT) allocation policy changed to limit MELD exception points for hepatocellular carcinoma (HCC) to median MELD at transplant minus three (MMaT-3). We evaluated this policy's impact on waitlist outcomes for HCC candidates, by race and ethnicity, hypothesizing that the introduction of the MMaT-3 reduced inequities in waitlist outcomes. METHODS: Retrospective cohort study of the Scientific Registry for Transplant Recipients, including all adult LT candidates (N = 10 751) who received HCC exception points from May 17, 2017 to May 18, 2019 (pre-policy; N = 6627) to May 19, 2019 to March 1, 2021 (post-policy; N = 4124). We compared incidence of LT and waitlist removal for death or becoming too sick pre- and post-policy for non-Hispanic White, non-Hispanic Black, Hispanic/Latinx, and Asian patients using competing risk regression adjusted for candidate characteristics. RESULTS: One-year cumulative incidence of LT decreased significantly pre-/post-policy among White (77.4% vs. 64.5%; p < .01) and Black (76.2% vs. 63.1%; p < .01) candidates only, while a 1-year incidence of death/non-LT waitlist removal decreased significantly only among Hispanics (13.4% vs. 7.5%; p < .01). After covariate adjustment, the effect of the policy change was a significantly decreased incidence of LT for White (SHR: .63 compared to pre-policy; p < .001), Black (SHR: .62; p < .001), and Asian (SHR: .68; p = .002), but no change for Hispanic patients. Only Hispanic patients had a significant decrease in death/waitlist removal after the policy change (SHR:  .69; p = .04). Compared to White patients in the pre-policy era, Hispanic (SHR:  .88, p < .007) and Asian candidates (SHR:  .72; p < .001) had lower unadjusted incidence of LT. This disparity was mitigated in the post-policy era where Hispanic patients had higher likelihood of LT than Whites (SHR: 1.22; p = .002). For the outcome of death/non-LT waitlist removal, the only significant difference was a 42% lower incidence of waitlist removal for Asian compared to White patients in the post-policy era (SHR:  .58; p = .03). CONCLUSION: Among LT recipients with HCC, racial/ethnic subpopulations were differentially affected by the MMAT-3 policy, resulting in a post-policy reduction of some of the previous disparities.


Asunto(s)
Carcinoma Hepatocelular , Etnicidad , Neoplasias Hepáticas , Trasplante de Hígado , Obtención de Tejidos y Órganos , Listas de Espera , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Carcinoma Hepatocelular/cirugía , Carcinoma Hepatocelular/mortalidad , Etnicidad/estadística & datos numéricos , Estudios de Seguimiento , Disparidades en Atención de Salud/estadística & datos numéricos , Neoplasias Hepáticas/cirugía , Neoplasias Hepáticas/mortalidad , Pronóstico , Grupos Raciales/estadística & datos numéricos , Sistema de Registros/estadística & datos numéricos , Estudios Retrospectivos , Tasa de Supervivencia , Obtención de Tejidos y Órganos/estadística & datos numéricos , Negro o Afroamericano , Hispánicos o Latinos , Asiático , Blanco
2.
Digestion ; : 1-16, 2024 Sep 24.
Artículo en Inglés | MEDLINE | ID: mdl-39317165

RESUMEN

INTRODUCTION: Etrasimod is an oral, once-daily (QD), selective sphingosine 1-phosphate (S1P)1,4,5 receptor modulator for the treatment of moderately to severely active ulcerative colitis (UC). Here we report the primary analysis of a phase 3 trial evaluating the efficacy and safety of etrasimod in patients from Japan with moderately to severely active UC. METHODS: Patients from Japan who completed the 12-week ELEVATE UC 12 induction trial could enroll in the 40-week ELEVATE UC 40 JAPAN maintenance trial for a combined 52-week treatment period. Patients in this Japan cohort continued their baseline assigned treatment (etrasimod 2 mg QD or placebo) from ELEVATE UC 12. Efficacy was assessed at Week 12 and Week 52. Treatment-emergent adverse events (TEAEs) pooled from both trials were assessed up to 52 weeks of exposure. RESULTS: The Japan cohort comprised 32 and 16 patients who received etrasimod and placebo, respectively. A numerically greater proportion of patients who received etrasimod versus placebo achieved clinical remission at Week 12 (etrasimod: 14.3%; placebo: 7.1%) and Week 52 (etrasimod: 25.0%; placebo: 7.1%); a similar trend was observed for all key secondary efficacy endpoints. TEAEs occurred in 84.4% (27/32) and 62.5% (10/16) of patients who received etrasimod and placebo, respectively. No new safety signals were detected. CONCLUSION: In these induction and maintenance trials evaluating etrasimod in patients from Japan with UC, numerically higher proportions of patients who received etrasimod versus placebo achieved efficacy endpoints. Efficacy and safety findings were consistent with those from the global ELEVATE UC trial populations. CLINICALTRIALS: gov: NCT03945188; NCT03996369; NCT04706793.

3.
J Exp Bot ; 74(17): 5255-5272, 2023 09 13.
Artículo en Inglés | MEDLINE | ID: mdl-37249250

RESUMEN

Pistia stratiotes is an aquatic plant with a complex structure that allows it to stay afloat. It grows quickly, and in large numbers becomes an undesirable plant as an invasive species. Describing the dynamics of a water drop splash on P. stratiotes leaves can contribute to increasing knowledge of its behavior and finding alternative methods for eradicating it or using it for the benefit of the environment. The non-wettable surface of P. stratiotes presents a complex structure-simple uniseriate trichomes and also ridges and veins. We analyzed the drop impact on a leaf placed on the water surface and recorded it by high-speed cameras. Based on the recordings, quantitative and qualitative analyses were performed. After impacting the leaf, the water drop spread until it reached its maximum surface area accompanied by the ejection of early droplets in the initial stage. Thereafter, three scenarios of water behavior were observed: (i) drop receding and stabilization; (ii) drop receding and ejection of late droplets formed in the later stage as an effect of elastic deformation of the leaf; and (iii) drop breaking apart and ejection of late droplets. The results indicated that the increasing kinetic energy of the impacting drops expressed by the Weber number and the complex leaf surface have an effect on the course of the splash. The simple uniseriate trichomes of the P. stratiotes leaf and the high energy of the falling drops were responsible for the formation and characteristics of the early droplets. The presence of ridges and veins and the leaf's mechanical response had an impact on the occurrence of late droplets.


Asunto(s)
Araceae , Interacciones Hidrofóbicas e Hidrofílicas , Plantas , Hojas de la Planta/fisiología , Agua/análisis
4.
J Am Acad Dermatol ; 86(1): 122-130, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34555481

RESUMEN

BACKGROUND: Psoriasis affects 0.13%-2.1% of children and adolescents. Despite a high unmet need, the current treatment options approved for pediatric psoriasis are limited. OBJECTIVE: To evaluate the efficacy and safety of 2 secukinumab dosage regimens (low dose: 75/75/150 mg; high dose: 75/150/300 mg) stratified and randomized by weight (<25 kg, 25 to <50 kg, ≥50 kg) and disease severity (moderate, severe) in pediatric patients aged 6-<18 years with moderate to severe plaque psoriasis. METHODS: This is a phase 3, open-label, randomized, multicenter study (NCT03668613). RESULTS: Both secukinumab doses were superior to historical placebo with respect to psoriasis area and severity index (PASI)-75/90 and investigator global assessment 0/1 responses at week 12. The estimated probability of a positive treatment effect (ie, log odds ratio > 0) for low- or high-dose secukinumab compared to historical placebo is 1 (ie, 100%). For the low and high doses at week 12, the investigator global assessment 0/1 response rates were 78.6% and 83.3%, respectively, and the PASI-90 response rates were 69% and 76.2%, respectively. The PASI-75 response rate was 92.9% for both the doses. LIMITATIONS: This is an open-label study design without a control arm. CONCLUSION: Secukinumab dosing regimens were efficacious and well tolerated in pediatric patients with moderate to severe plaque psoriasis.


Asunto(s)
Anticuerpos Monoclonales , Psoriasis , Adolescente , Anticuerpos Monoclonales/efectos adversos , Anticuerpos Monoclonales Humanizados , Niño , Método Doble Ciego , Humanos , Psoriasis/inducido químicamente , Psoriasis/diagnóstico , Psoriasis/tratamiento farmacológico , Índice de Severidad de la Enfermedad , Resultado del Tratamiento
5.
Sensors (Basel) ; 23(1)2022 Dec 23.
Artículo en Inglés | MEDLINE | ID: mdl-36616719

RESUMEN

Water erosion is an unfavorable phenomenon causing soil degradation. One of the factors causing water erosion is heavy or prolonged rainfall, the first effect of which is the deformation of the soil surface and the formation of microcraters. This paper presents an overview of research methods allowing the study of microcraters as well as the process of their formation. A tabular summary of work on the measurements of various quantities describing the craters is presented. The said quantities are divided into three groups: (i) static quantities, (ii) dynamic quantities, and (iii) dimensionless parameters. The most important measurement methods used to study crater properties, such as (i) basic manual measurement methods, (ii) photography, (iii) high-speed imaging, (iv) profilometers, (v) 3D surface modelling, and (vi) computed tomography (CT) and its possibilities and limitations are discussed. The main challenges and prospects of research on soil surface deformation are also presented.

6.
Phys Rev Lett ; 127(19): 190401, 2021 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-34797125

RESUMEN

Spin-orbit interactions which couple the spin of a particle with its momentum degrees of freedom lie at the center of spintronic applications. Of special interest in semiconductor physics are Rashba and Dresselhaus spin-orbit coupling. When equal in strength, the Rashba and Dresselhaus fields result in SU(2) spin rotation symmetry and emergence of the persistent spin helix only investigated for charge carriers in semiconductor quantum wells. Recently, a synthetic Rashba-Dresselhaus Hamiltonian was shown to describe cavity photons confined in a microcavity filled with optically anisotropic liquid crystal. In this Letter, we present a purely optical realization of two types of spin patterns corresponding to the persistent spin helix and the Stern-Gerlach experiment in such a cavity. We show how the symmetry of the Hamiltonian results in spatial oscillations of the spin orientation of photons traveling in the plane of the cavity.

7.
Liver Transpl ; 25(12): 1800-1810, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31539195

RESUMEN

The high efficacy of current hepatitis C virus (HCV) therapy and increased numbers of HCV-infected deceased donors have changed the paradigm of HCV in liver transplantation (LT). Modeling studies have been performed to evaluate the optimal timing of HCV treatment (before versus after LT) in HCV-infected patients and to assess the cost-effectiveness of transplanting HCV-infected livers into HCV- patients. However, these models rely on historical data and have not quantified the temporal changes in the median Model for End-Stage Liver Disease (MELD) score at transplant of recipients of an HCV-infected liver across geographic areas. We performed a retrospective cohort study of Organ Procurement and Transplantation Network/United Network for Organ Sharing (UNOS) data of nonstatus 1 deceased donor LT recipients from January 1, 2016, to December 31, 2018, and we calculated the difference in allocation MELD score in recipients of HCV nucleic acid test (NAT)- versus NAT+ livers by year and UNOS region. We used Pearson correlation coefficients to assess the relationship between MELD score difference in recipients of HCV NAT+ versus HCV NAT- livers and the proportion of non-HCV recipients of HCV NAT+ livers. Nationally, the allocation MELD score difference at LT in recipients of HCV NAT+ versus NAT- livers did not change (4-point difference). This stability was seen in regions 3, 5, and 10. In regions 1, 7, 8, 9, and 11, the MELD score difference decreased, which is a diminishing advantage. However, in regions 2 and 4, it increased, which is a rising advantage. In 2018, recipients of HCV NAT+ livers had a lower MELD score in 9/11 regions, and the MELD score advantage of accepting HCV NAT+ livers had a moderate inverse correlation with the regional use in non-HCV patients (r = -0.53). These data should be used to inform clinicians of the pre- and post-LT trade-offs of HCV treatment.


Asunto(s)
Selección de Donante/tendencias , Enfermedad Hepática en Estado Terminal/cirugía , Hepatitis C/diagnóstico , Trasplante de Hígado/tendencias , Asignación de Recursos/tendencias , Viremia/diagnóstico , Adulto , Aloinjertos/provisión & distribución , Aloinjertos/virología , Antivirales/uso terapéutico , Selección de Donante/estadística & datos numéricos , Enfermedad Hepática en Estado Terminal/diagnóstico , Geografía , Hepacivirus/genética , Hepacivirus/aislamiento & purificación , Hepatitis C/sangre , Hepatitis C/tratamiento farmacológico , Hepatitis C/transmisión , Humanos , Hígado/virología , Trasplante de Hígado/estadística & datos numéricos , ARN Viral/aislamiento & purificación , Asignación de Recursos/estadística & datos numéricos , Estudios Retrospectivos , Índice de Severidad de la Enfermedad , Receptores de Trasplantes/estadística & datos numéricos , Estados Unidos , Viremia/tratamiento farmacológico , Viremia/transmisión , Viremia/virología
8.
J Emerg Med ; 56(2): 217-221, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30559044

RESUMEN

BACKGROUND: Ovarian hyperstimulation syndrome (OHSS) is a common complication of an in-vitro fertilization (IVF) procedure, which is usually clinically insignificant. However, without monitoring, it can progress into a life-threatening condition. With the increasing popularity of IVF technology, patients with OHSS may begin visiting emergency departments (EDs) more frequently. CASE REPORT: We report the case of a patient admitted to the ED presenting with severe abdominal pain, cough, and nausea. An ultrasound examination was inconclusive. Computer tomography revealed enlarged ovaries and fluid in the pleural cavities, around the liver and spleen, between the bowel loops, and in the pelvis. This prompted physicians to review the patient's fertility issues. Consequently, the diagnosis of OHSS was made. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: When the physician knows that the patient is undergoing IVF, the diagnosis of OHSS can be straightforward; without this information, it can be difficult. Having in mind the growing demand for infertility treatment, we present this case to increase awareness of possible clinical findings and complications of OHSS as a rare consequence of IVF. OHSS diagnosed via ultrasound can reduce the emotional, financial, and health burden of infertile couples and help them to fulfill their procreation plans without unnecessary delay.


Asunto(s)
Fertilización In Vitro/efectos adversos , Síndrome de Hiperestimulación Ovárica/diagnóstico , Dolor Abdominal/diagnóstico por imagen , Dolor Abdominal/etiología , Adulto , Tos/etiología , Servicio de Urgencia en Hospital/organización & administración , Femenino , Fertilización In Vitro/métodos , Humanos , Infertilidad/terapia , Náusea/etiología , Síndrome de Hiperestimulación Ovárica/fisiopatología , Tomografía Computarizada por Rayos X/métodos
9.
Pol J Radiol ; 83: e171-e174, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30627231

RESUMEN

Radiomics is a new concept that has been functioning in medicine for only a few years. This idea, created recently, relies on processing innumerable quantities of metadata acquired from every examination, followed by extraction thereof from relevant imaging examinations, such as computer tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET) images, by means of appropriate created algorithms. The extracted results have great potential and broad possibilities of application. Thanks to these we can verify efficiency of treatment, predict locations of metastases of tumours, correlate results with histopathological examinations, or define the type of cancer more precisely. In effect, we obtain more personalised treatment for each patient, which is extremely important and highly recommendable in the tests and applicable treatment therapies conducted nowadays. Radiomics is a non-invasive and high efficiency post-processing method. This article is intended to explain the idea of radiomics, the mechanisms of data acquisition, existing possibilities, and the challenges incurred by radiologists and physicians at the stage of making diagnosis or conducting treatment.

10.
Pol J Radiol ; 83: e210-e214, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30627237

RESUMEN

PURPOSE: Lymphoproliferative neoplasms are the largest and most frequently diagnosed entities in the group of haematological malignancies. The aim of the study was to assess whether apparent diffusion coefficient (ADC) measured on the first day of the second cycle of chemotherapy could be a predictor of prognosis and of the final treatment's outcome. MATERIAL AND METHODS: The study included 27 patients with diagnosed Hodgkin's and non-Hodgkin's lymphoma, who had magnetic resonance (MR) performed with diffusion weighted imaging/apparent diffusion coefficient (DWI/ADC) before and on the first day of the second cycle of chemotherapy. Imaging was performed using a 1.5 T MR scanner. ADC was measured in lymphoma infiltration in the area of the lowest signal in the ADC map and the highest signal on ß 800 images in post-treatment study. After that, the corresponding area was determined in a pre-treatment study and an ADC value was measured. RESULTS: The difference between ADC values in pre-treatment (ADC = 720 mm2/s) and post-treatment (ADC = 1059 mm2/s) studies was statistically significant (p < 0.001). Cutoff values for estimating response to treatment were established at the level of ADC 1080 mm2/s, and ADC to muscle ratio at 0.82 in post-treatment study. Patients with ADC > 752 mm2/s before treatment manifested lower probability of progression than patients with ADC < 752 mm2/s. CONCLUSIONS: ADC measurement's before treatment and on the first day of the second cycle of chemotherapy can be used as a prognostic marker in lymphoma therapy. ADC values lower than 1080 mm2/s and an increase of the ratio after the treatment can be considered as a marker of disease progression.

11.
Pol J Radiol ; 81: 536-539, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27920840

RESUMEN

BACKGROUND: MRCP is the method of choice in diagnosing pathologies of the biliary system. One of them is bile fistulae. They are uncommon but tend to cause many diagnostic problems. The possible way to improve MRCP is using it with intravenous injection of hepatobiliary-specific contrast agents. As it is eliminated via the hepatobiliary system, it can be visualized in the bile ducts and may help to reveal disorders undetected by a standard MRCP. CASE REPORT: We report a case of a 36-year-old woman with leakage in the biliary system which led to creation of a subcutaneous bile reservoir. By means of a regular MRCP protocol it was impossible to reveal any disorders of the biliary system and thus a decision to inject Gd-EOB-DTPA was taken. As a result, a fistula with its opening in the fundus of the gall bladder was revealed. Patient was qualified for treatment with somatostatin analogues in order to stop bile secretion. CONCLUSIONS: The Gd-EOB-DTPA in combination with regular T2-weighted MRCP may be helpful in detecting anomalies of the biliary system. Although a high price of the procedure restricts its accessibility, such advantages as lower risk of complications, lower costs of hospitalization, and less traumatic nature make it a technique that may take precedence over ERCP in ambiguous cases.

13.
Transplantation ; 108(1): 204-214, 2024 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-37189232

RESUMEN

BACKGROUND: Patients with hepatocellular carcinoma (HCC) have been overprioritized in the deceased donor liver allocation system. The United Network for Organ Sharing adopted a policy in May 2019 that limited HCC exception points to the median Model for End-Stage Liver Disease at transplant in the listing region minus 3. We hypothesized this policy change would increase the likelihood to transplant marginal quality livers into HCC patients. METHODS: This was a retrospective cohort study of a national transplant registry, including adult deceased donor liver transplant recipients with and without HCC from May 18, 2017, to May 18, 2019 (prepolicy) to May 19, 2019, to March 1, 2021 (postpolicy). Transplanted livers were considered of marginal quality if they met ≥1 of the following: (1) donation after circulatory death, (2) donor age ≥70, (3) macrosteatosis ≥30% and (4) donor risk index ≥95th percentile. We compared characteristics across policy periods and by HCC status. RESULTS: A total of 23 164 patients were included (11 339 prepolicy and 11 825 postpolicy), 22.7% of whom received HCC exception points (prepolicy versus postpolicy: 26.1% versus 19.4%; P = 0.03). The percentage of transplanted donor livers meeting marginal quality criteria decreased for non-HCC (17.3% versus 16.0%; P < 0.001) but increased for HCC (17.7% versus 19.4%; P < 0.001) prepolicy versus postpolicy. After adjusting for recipient characteristics, HCC recipients had 28% higher odds of being transplanted with marginal quality liver independent of policy period (odds ratio: 1.28; confidence interval, 1.09-1.50; P < 0.01). CONCLUSIONS: The median Model for End-Stage Liver Disease at transplant in the listing region minus 3 policy limited exception points and decreased the quality of livers received by HCC patients.


Asunto(s)
Carcinoma Hepatocelular , Enfermedad Hepática en Estado Terminal , Neoplasias Hepáticas , Trasplante de Hígado , Obtención de Tejidos y Órganos , Adulto , Humanos , Carcinoma Hepatocelular/cirugía , Carcinoma Hepatocelular/patología , Trasplante de Hígado/efectos adversos , Neoplasias Hepáticas/cirugía , Neoplasias Hepáticas/patología , Enfermedad Hepática en Estado Terminal/diagnóstico , Enfermedad Hepática en Estado Terminal/cirugía , Estudios Retrospectivos , Donadores Vivos , Selección de Paciente , Índice de Severidad de la Enfermedad , Políticas , Listas de Espera
14.
JAMA Surg ; 2024 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-39230915

RESUMEN

Importance: Women on the liver transplant waiting list are less likely to undergo a transplant than men. Recent approaches to resolving this disparity have involved adjustments to Model for End-Stage Liver Disease (MELD) scoring, but this will not affect candidates who rely on exception scores rather than calculated MELD score, the majority of whom have hepatocellular carcinoma (HCC). Objective: To evaluate the association between female sex, candidate size, and access to liver transplant among wait-listed patients with HCC. Design, Setting, and Participants: This retrospective cohort study used US transplant registry data of all adult (aged ≥18 years) wait-listed liver transplant candidates receiving an HCC exception score between January 1, 2010, and March 2, 2023. Exposure: Wait-listed liver transplant candidate sex. Main Outcomes and Measures: The association of female sex with (1) deceased-donor liver transplant (DDLT) and (2) death or waiting list removal for health deterioration were estimated using multivariable competing-risks regression. Results with and without adjustment for candidate height and weight (mediators of the sex disparity) were compared. Results: The cohort included 31 725 candidates with HCC (mean [SD] age at receipt of exception, 61.2 [7.1] years; 76.3% men). Compared with men, women had a lower 1-year cumulative incidence of DDLT (50.8% vs 54.0%; P < .001) and a higher 1-year cumulative incidence of death or delisting for health deterioration (16.2% vs 15.0%; P = .002). After adjustment, without accounting for size, women had a lower incidence of DDLT (subdistribution hazard ratio [SHR], 0.92; 95% CI, 0.89-0.95) and higher incidence of death or delisting (SHR, 1.06; 95% CI, 1.00-1.13) compared with men. When adjusting for candidate height and weight, there was no association of female sex with incidence of DDLT or death or delisting. However, at a height cutoff of 166 cm, short women compared with short men were still less likely to undergo a transplant (SHR, 0.93; 95% CI, 0.88-0.99). Conclusions and Relevance: In this study, women with HCC were less likely to receive a DDLT and more likely to die while wait-listed than men with HCC; these differences were largely (but not entirely) explained by sex-based differences in candidate size. For candidates listed with exception scores, additional changes to allocation policy are needed to resolve the sex disparity, including solutions to improve access to size-matched donor livers for smaller candidates.

15.
PLoS One ; 18(5): e0285611, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37172020

RESUMEN

The splash phenomenon and the scale of the surface deformation of post-fire soils in the variants of various hydrophobicity and moisture content were studied. Splash erosion is the result of the impact of a single water drop and was analysed using high-speed cameras, while the surface deformation was parameterized using a structured light scanner. The extremely water-repellent variant (dry_V) showed distinct differences, expressed primarily in the number of ejected particles, which was 2.5 times higher than in the four soils with lower levels of hydrophobicity. It was also observed that as a result of the drop impact onto an extremely hydrophobic soil surface, a form known as liquid marble was created inside the crater. Soil moisture content determined the manner, scale and dynamics of the splash erosion. In the case of wet soils, the phenomenon proceeded up to five times faster, and as a result of the drop impact, a large number of fine particles were ejected, which reached nearly twice the velocities and three times the displacement distances compared to the dry soil group. However, the particles and/or aggregate splashed on the dry samples were larger, which also translated into the formation of craters up to twice as extensive as those in the wet soils.


Asunto(s)
Suelo , Agua , Suelo/química , Interacciones Hidrofóbicas e Hidrofílicas , Agua/química
16.
PLoS One ; 17(1): e0262203, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34995324

RESUMEN

Soil splash is the first step in the process of water erosion, where impacting raindrops cause the detachment and transport of soil material. One of the factors that strongly influences the magnitude of soil splash is the incline of the surface (slope). The aim of this study was to investigate the effect of the slope on the course of the splash phenomenon caused by single-drop impact (one drop impact per soil sample), with respect to the mass and proportions of the ejected material, taking into account its division into solid and liquid phases i.e. soil and water. The investigation was carried out using three types of soil with different textures, in moistened (pressure head corresponding to -1.0 kPa) and air-dry (-1500 kPa) conditions. The soil samples were on three angles of slope, being 5°, 15°, and 30°, respectively. After a single-drop impact with a diameter of 4.2 mm, the ejected material was collected using a splash cup. The following quantities of splashed material were measured: the total mass, the mass of the solid phase, and the mass of the liquid phase. Additionally, the distribution and proportions (soil/water) of the splashed material were analysed in both the upslope and downslope directions. It was found that: (i) the change of slope had a variable influence on the measured quantities for different soils; (ii) in the case of moistened samples, the measured values were mainly influenced by the texture, while in the dry samples, by the angle of the slope; (iii) with the increase of slope, the splashed material was mostly ejected in the downslope direction (irrespective of moisture conditions); (iv) in the moistened samples, the ejected material consisted mostly of water, while in the dry samples it was soil-this occurred for material ejected both upslope and downslope. The obtained results are important for improving the physical description of the process of splash erosion. A more thorough understanding and better recognition of the mechanisms governing this phenomenon at all stages could contribute to the development of more effective methods for protecting soil against erosion.


Asunto(s)
Transición de Fase , Lluvia , Suelo/química , Agua/análisis , Agua/química , Fenómenos Mecánicos , Propiedades de Superficie
17.
ACS Omega ; 7(11): 9785-9795, 2022 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-35350322

RESUMEN

Flexoelectricity may have an important impact on the switching properties of nematic and cholesteric liquid crystals due to the linear coupling between the flexoelectric polarization of the liquid crystal and the applied electric field. This coupling is the origin of the extraordinary electro-optic effect in cholesterics aligned in the uniform lying helix texture, resulting in fast switching and field control of both rise and fall times. Therefore, the flexoelectric properties of the liquid crystals have become an important issue when designing and synthesizing liquid crystal materials and/or preparing their mixtures with appropriate flexoelectric compounds (dopants). Here, we report on the flexoelectric polarization of a highly polar nematic liquid crystal host enhanced by doping it with two newly synthesized dopants SK 1-6 and SK 1-8, possessing a hockey stick molecular shape, and comparing their doping effect with the one of the dimeric dopants CB7CB possessing a symmetric bend molecular shape. All dopants were dissolved in small concentration (5 wt %) in the nematic host so that the linear approximation of the dependence of the difference between splay e s and bend e b flexoelectric constants, that is, (e s - e b), on the concentration of the dopant in the host material can be applied. In this way, (e s - e b) was estimated for the hockey stick dopants SK 1-6 and SK 1-8 to be 0.182 and 0.204 nC/m, respectively. The obtained flexoelectric polarization of these dopants is among the highest reported in the literature so far.

18.
PLoS One ; 17(3): e0265546, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35333882

RESUMEN

The formation of craters is an important issue in the investigations of the surface of the earth and other planets. The aim of the study was to check whether the different textures of sand beds affect the size and dynamics of the formation of craters and ejection curtain after high-velocity impacts. The experiments were conducted using an aluminium impactor at two impact speeds (~700 and ~1300 m∙s-1) and a sand bed composed of either a broad range of sizes (<2.0 mm) or any of the three fractions obtained from it (<0.5, 0.5-1, 1-2 mm). The diameters, depths, wall slope, and rim heights of the resulting craters were measured. The ejecta curtain was characterized by the inclination angle of walls, base diameter, and expansion velocity. The mass of the transferred material and the depth of the impactor penetration were also determined. Additionally, the results were used to calculate dimensionless parameters commonly considered in crater studies (πV, π2 and α). The texture of the sand most clearly influenced the diameters of the craters, its effect could also be seen in the case of the distance covered by the ejected material. This information appears to be relevant for future research, providing some rationale to help assess in which aspects of the phenomenon the texture may be important.


Asunto(s)
Planetas , Arena , Planeta Tierra
19.
Sci Adv ; 8(40): eabq7533, 2022 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-36197989

RESUMEN

The field of spinoptronics is underpinned by good control over photonic spin-orbit coupling in devices that have strong optical nonlinearities. Such devices might hold the key to a new era of optoelectronics where momentum and polarization degrees of freedom of light are interwoven and interfaced with electronics. However, manipulating photons through electrical means is a daunting task given their charge neutrality. In this work, we present electrically tunable microcavity exciton-polariton resonances in a Rashba-Dresselhaus spin-orbit coupling field. We show that different spin-orbit coupling fields and the reduced cavity symmetry lead to tunable formation of the Berry curvature, the hallmark of quantum geometrical effects. For this, we have implemented an architecture of a photonic structure with a two-dimensional perovskite layer incorporated into a microcavity filled with nematic liquid crystal. Our work interfaces spinoptronic devices with electronics by combining electrical control over both the strong light-matter coupling conditions and artificial gauge fields.

20.
Radiol Case Rep ; 15(6): 775-779, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32322330

RESUMEN

Trifurcation is rare anatomical variant of the common carotid artery (CCA) termination. Knowledge of such alteration may prevent from the unintentional complications and influence on the course of various invasive medical procedures carried in the neck region. The best way to assess anatomy of neck arteries is computed tomography angiography (CTA). In this article we present a case of 64-year old male patient, who was admitted to the department with a chronic headaches and dizziness. CTA revealed a trifurcation of the right common carotid artery into: internal carotid artery and two branches of external carotid artery. The aneurysm of the proximal part of Vertebral Artery was also observed and it was considered as a cause of the symptoms which should not be related to the anatomical variety of the CCA.

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