Three-dimensional submerged wall jets and their transition to density flows: Morphodynamics and implications for the depositional record

Jets that expand from an orifice into an ambient water body represent a basic flow model for depositional environments related to expanding flows. Momentum-dominated jets evolve into gravity-dominated density flows. To understand this transition and its sedimentological relevance, three-dimensional tank experiments with submerged wall jets were conducted, systematically varying parameters such as the initial density difference, bed slope, grain size and sediment supply. Bedform successions could be subdivided into those related to the jet and those related to the density flow. Jet deposits included early-stage bedforms, scours and mouth bars. Early-stage bedforms are asymmetrical dunes that spread concentrically from the orifice. Sediment entrainment by eddies from the expanding jets led to the formation of scours and mouth bars. Flows with lesser initial density difference produced more elongate scours. Conversely, scours became deeper for denser incoming flows. Coarser-grained sediment caused the formation of higher and steeper mouth bars and vice versa. The transition from momentum-dominated jets to gravity-dominated density flows occurred approximately at the mouth-bar crest. Hydraulic jumps were absent in the expanding jet regions and at the transitions to density flows. Instead, complex flow patterns and circulations were inferred from the velocity measurements within the scour and at the mouth-bar crests. Bedform trains related to the density flow were controlled by the grain size and sediment supply. Coarse-grained sediment and high supply rates caused strong mouth-bar aggradation and flow splitting, leading to the formation of bedform trains laterally adjacent to the mouth bar. Fine-grained sediment and low supply rates caused the formation of bedform trains downflow of the mouth bar. The symmetrical bedforms deposited by the density flows always displayed an in-phase relationship with the flow, indicating that they were antidunes. The experimental jet deposits resemble successions known from subaqueous ice-contact fans and deep water channel-lobe transition zones

Turbidity currents generating lobes: flow rate influence on 3D experiments without slope break

Turbidity current hydrodynamic properties are evaluated experimentally to understand the formation of turbidity current depositional lobes and the relationship with flow properties, in particular, flow rates. This study focused on the depositional behavior of unconfined turbidity currents through the analysis of three-dimensional experiments performed in a large-scale channel-basin tank without slope break. Three flow rates were simulated when flow velocities, both in longitudinal and transversal directions, were measured and resulting depositional features were evaluated. The three-dimensional physical experiments carried out in this work allowed the identification of two flow rate models with different hydrodynamic characteristics and two distinct lobes. Lower flow rates produced elongated lobate deposits, with characteristic lower flow regime plane bed on the surfaces, characteristic downstream sediment fining that resulted from lower flow velocities, and visibly less turbulent flows from less competent and waning turbidity currents. Higher flow rates showed a more characteristic radial and downstream fining sediment with lobe surfaces displaying ripples and dunes, generated by the higher flow velocities, presumably more turbulent, and more competent turbidity currents

Re-examining models of shallow-water deltas: Insights from tank experiments and field examples

Shallow-water deltas remain enigmatic in terms of placing the observed facies within a coherent process-based depositional model. Here we report tank experiments on mouth-bar formation from shallow water pure and stratified jets that, combined with recent flume experiments on bedforms, suggest new interpretations of field observations from shallow-water delta outcrops. Our experiments imply that the height, geometry and bedforms of the mouth bars depend on the jet properties and grain size of the supplied sediment. Pure jets with very coarse-grained sediment formed a high and steep mouth bar that is characterised by steep angle-of-repose cross bedding with related avalanche processes (grain flows) on the lee side. The experiments with stratified jets imply that mouth-bar deposition and growth are dominated by supercritical density flows that evolve from the initial jets on the lee side of the growing mouth bar. In stratified jets with very coarse-grained sediment, deposition on the mouth-bar lee side was both from grain-flow avalanches and density flows. While deposition on the upper lee slope was dominated by grain flows, a concentric field of low relief, asymmetric, downflow-migrating bedforms evolved on the lower slope and beyond the mouth bar. In the stratified jet with medium-grained sediment a very low relief mouth bar formed within a concentric field of low, asymmetric, downflow-migrating bedforms covering the entire lee slope and the area beyond. Many previous field studies show that mouth bars deposited from dense stratified jets (hyperpycnal flows) are characterised by a distinct facies assemblage of coarse-grained cross-stratified or low-angle cross-stratified sandstone passing downslope into finer-grained plane-parallel, or “quasi-parallel” laminated sand and into climbing-ripple cross-laminated sandstone. Comparison to flume and tank experiments suggests that the proximal coarse-grained planar and trough cross-stratified sandstones could represent deposition by supercritical dunes that pass downslope into antidunes, characterised by sinusoidal stratification and/or low-angle cross stratification. The repeated vertical transition between antidune deposits and climbing-ripple cross-laminated sandstone may indicate the superposition of ripples onto antidunes in finer-grained sediments, indicating ripple formation under supercritical flow conditions. Similar bedforms/sedimentary structures have previously been interpreted as hummocky cross-stratification or swaley cross-stratification and attributed to combined flows in storm-dominated settings, which probably in some cases must be revised

Soft transition between subcritical and supercritical currents through intermittent cascading interfacial instabilities

Long-running gravity currents are flows that are submerged beneath a deep layer of quiescent fluid and they travel over long distances along inclined or horizontal surfaces. They are driven by the density difference between the current and the clear ambient fluid above. In this work we present results on highly resolved direct numerical simulations of turbid underflows that involve nearly 1 billion degrees of freedom. We assess the effect of bed slope on the flow statistics. We explore the turbulence dynamics of the interface in the classical sub-A nd supercritical regimes. We investigate the structure of interfacial turbulence and its relation to the turbulence statistic. A transcritical regime is identified where intermittent cascading interfacial instabilities appear. We investigate how departure from the self-sustaining equilibrium state may be the mechanism responsible for this cyclic evolution of the transcritical regime.Fil: Salinas, Jorge. University of Florida; Estados UnidosFil: Balachandar, S.. University of Florida; Estados UnidosFil: Shringarpure, Mrugesh. No especifíca;Fil: Fedele, Juan. No especifíca;Fil: Hoyal, David. No especifíca;Fil: Cantero, Mariano Ignacio. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro | Universidad Nacional de Cuyo. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin

Circadian disruption promotes tumor-immune microenvironment remodeling favoring tumor cell proliferation

Circadian disruption negatively affects physiology, posing a global health threat that manifests in proliferative, metabolic, and immune diseases, among others. Because outputs of the circadian clock regulate daily fluctuations in the immune response, we determined whether circadian disruption results in tumor-associated immune cell remodeling, facilitating tumor growth. Our findings show that tumor growth rate increased and latency decreased under circadian disruption conditions compared to normal light-dark (LD) schedules in a murine melanoma model. Circadian disruption induced the loss or inversion of daily patterns of M1 (proinflammatory) and M2 (anti-inflammatory) macrophages and cytokine levels in spleen and tumor tissues. Circadian disruption also induced (i) deregulation of rhythmic expression of clock genes and (ii) of cyclin genes in the liver, (iii) increased CcnA2 levels in the tumor, and (iv) dampened expression of the cell cycle inhibitor p21WAF/CIP1, all of which contribute to a proliferative phenotype.Fil: Aiello, Ignacio. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Virginia Tech University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mul Fedele, Malena Lis. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Román, F.. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; ArgentinaFil: Marpegan, Luciano. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Caldart Valle, Carlos Sebastian. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chiesa, Juan José. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Golombek, Diego Andrés. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Finkielstein, C.V.. Virginia Tech University; Estados UnidosFil: Paladino, Natalia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Neuropatia incapacidade e aspectos ortopédicos da lepra na Guiné - Bissau

A lepra resulta da infecção por M. leprae. Manifesta-se fundamentalmente por lesões cutâneas e dos nervos periféricos podendo, no entanto, atingir outros órgãos e sistemas. A neuropatia periférica a nível dos membros, com consequente disfunção sensitiva e motora, pode culminar em lesões deformantes e gravemente incapacitantes. A terapêutica médica e cirúrgica, bem como a reabilitação têm um lugar importante na prevenção e no tratamento destas lesões. Este foi um estudo de carácter observacional, transversal e analítico, com o objectivo de caracterizar uma população de doentes com lepra no que se refere às sequelas do foro neuro-músculo-esquelético. Pretendeu-se avaliar o seu impacto em termos de incapacidade, de forma a determinar as necessidades no que respeita a intervenções preventivas e terapêuticas. A população estudada incluía dois grupos de doentes com diagnóstico de lepra – novos doentes (ND) e antigos doentes (AD) – internados ou seguidos em ambulatório no Hospital de Cumura, onde confluem todos os casos de lepra reportados na Guiné-Bissau. Para a colheita de dados foi realizada a consulta de registos clínicos do hospital, bem como a avaliação de doentes segundo um protocolo elaborado para o efeito. Para a classificação da incapacidade foi usado o Maximum Impairment Grade da OMS e o Eye Foot and Hand Score. A amostra consistiu em 82 doentes (54 ND e 28 AD). No grupo ND obteve-se 9,3% de indivíduos com idade inferior a 15 anos, 63,0% de indivíduos com doença do tipo multibacilar (MB) e 29,6% de indivíduos com incapacidade grau 2. Neste grupo os indivíduos paucibacilares (PB) apresentavam 10,0% de incapacidade grau 2 e os MB 41,2%. No grupo dos AD a incapacidade grau 2 ocorreu em 80,0% dos casos. Os troncos nervosos mais frequentemente envolvidos foram, por ordem decrescente de frequência: 1) nos ND, o tibial posterior, o mediano, o cubital, o ciático popliteu externo e o radial; 2) nos AD, o tibial posterior, o cubital, o mediano, o ciático popliteu externo e o radial. Os troncos nervosos que mais se associaram a lesões/deformidades foram nos ND e AD: o tibial posterior, cubital e mediano. As lesões dos membros mais frequentes foram: 1) nos ND, feridas e úlceras das mãos e dos pés, mutilação de dedos das mãos; 2) nos AD, mutilação das mãos e pés e mão em garra. O pé pendente/equino ocorreu apenas nos AD. Após o diagnóstico a maioria dos AD foram abandonados pela família ou amigos e encontravam-se dependentes nas actividades domésticas. Globalmente, 78% não retomou a sua actividade profissional (na maior parte das vezes ligada ao trabalho rural) ou mudou de ocupação. Os resultados obtidos sugerem que uma proporção importante de indivíduos está a ser diagnosticada tardiamente, o que pode corresponder a um maior número de casos detectados activamente em zonas antes não abrangidas pelas actividades de controlo da lepra. A maioria dos novos casos detectados eram MB, que correspondiam aos que apresentavam maior incapacidade. Os troncos nervosos mais atingidos foram os descritos na literatura, resultando nas lesões habituais. Estas são abordadas correctamente se passíveis de tratamento conservador, contudo parece escassear o recurso a soluções cirúrgicas. Estas lesões estiveram associadas a impacto negativo na qualidade de vida e integração social destes doentes. O estudo sugere que a detecção precoce da lepra e das lesões incapacitantes a ela associadas podem ser optimizadas no hospital de Cumura. Existe lugar para o tratamento cirúrgico que pode alterar a história natural da doença e suas consequências físicas, familiares e sociais.Leprosy is caused by M. leprae infection. The disease affects skin and peripheral nerve trunks and occasionally other organs. Peripheral neuropathy of the limbs may progress and impair sensitive and motor functions with subsequent deformity and severe impairment. Chemotherapy but also surgery and rehabilitation have a major role in preventing and treating these lesions. This observational, analytical, cross-sectional study was performed to describe a population of leprosy patients and to characterize the existing neuro-muscular-skeletal lesions and disabilities in order to evaluate the burden of disability and the need for future preventive and therapeutic measures. Two groups of patients with a leprosy diagnosis were studied – a new patients group (NP) and a former patients group (FP) –followed-up as inpatients or outpatients at the Cumura Hospital which manages all leprosy cases reported in Guinea-Bissau. Data was obtained from clinical records or direct patient observation according to a specially created case report form. For impairment classification the WHO Maximum Impairment Grade and the Eye Foot and Hand Score were used. 82 patients (54 NP and 28 FP) were studied. In the NP group 9.3% of patients were under 15 years-old; 63.0% were multibacillary (MB), and 29.6% presented with grade 2 disability. In the NP group grade 2 disability was detected in 10.0% of PB and 41.2% of MB patients. In the FP group 80.0% of patients presented with grade 2 disability. Globally, the most commonly affected nerve trunk was the posterior tibial nerve followed by: 1) the median, ulnar, lateral popliteal and radial in NP patients; 2) ulnar, median, lateral popliteal and radial in FP patients. The ones more commonly associated with deformity were the tibial posterior, the ulnar and the median nerves. Most commonly diagnosed deformities were: 1) palmar and plantar wounds and ulcers, fingers mutilation in NP; 2) hand and foot mutilation and claw fingers in FP. Only FP presented with equinus foot. After diagnosis most of FP were abandoned by family or friends and became dependent for daily household activities. Globally 78% stopped working (mainly in rural activities) or changed their occupation. These results suggest that leprosy is being late diagnosed in a relevant proportion of patients. This may be associated with an increase in active detection in areas formerly not covered by anti-leprosy activities. Most of the newly detected cases are MB which was associated to higher impairment grades. The most affected nerve trunks and its associated lesions were the ones usually described. These lesions were correctly managed when this involved conservative treatment but apparently access to surgical solutions was limited. These deformities were found to have a negative impact on the quality of life and social integration of these patients. This study indicates that there is room for improvement in the detection and management of leprosy and associated disabilities at the Cumura hospital, including the use of surgical techniques that can favorably change the natural history of the disease and its physical, family and social consequences

Ultrastrong coupling between electron tunneling and mechanical motion

The ultrastrong coupling of single-electron tunneling and nanomechanical motion opens exciting opportunities to explore fundamental questions and develop new platforms for quantum technologies. We have measured and modelled this electromechanical coupling in a fully-suspended carbon nanotube device and report a ratio of $g_m/\omega_m = 1.3$, where $g_m/2\pi = 420\pm20$~MHz is the coupling strength and $\omega_m/2\pi=324$~MHz is the mechanical resonance frequency. This is well within the ultrastrong coupling regime and the highest among current electromechanical platforms. Even higher ratios could be achieved with improvement on device design

Stability of long-sustained oscillations induced by electron tunneling

Self-oscillations are the result of an efficient mechanism generating periodic motion from a constant power source. In quantum devices, these oscillations may arise due to the interaction between single electron dynamics and mechanical motion. Due to the complexity of this mechanism, these self-oscillations may irrupt, vanish, or exhibit a bistable behavior causing hysteresis cycles. We observe these hysteresis cycles and characterize the stability of different regimes in single and double quantum dot configurations. In particular cases, we find these oscillations stable for over 20 seconds, many orders of magnitude above electronic and mechanical characteristic timescales, revealing the robustness of the mechanism at play. The experimental results are reproduced by our theoretical model that provides a complete understanding of bistability in nanoelectromechanical devices.Comment: 11 pages, 10 figures, includes the complete paper and the Supplemental Materia

Gaia DR2 view of the Lupus V-VI clouds: The candidate diskless young stellar objects are mainly background contaminants

Extensive surveys of star-forming regions with Spitzer have revealed populations of disk-bearing young stellar objects. These have provided crucial constraints, such as the timescale of dispersal of protoplanetary disks, obtained by carefully combining infrared data with spectroscopic or X-ray data. While observations in various regions agree with the general trend of decreasing disk fraction with age, the Lupus V and VI regions appeared to have been at odds, having an extremely low disk fraction. Here we show, using the recent Gaia data release 2 (DR2), that these extremely low disk fractions are actually due to a very high contamination by background giants. Out of the 83 candidate young stellar objects (YSOs) in these clouds observed by Gaia, only five have distances of ∼150 pc, similar to YSOs in the other Lupus clouds, and have similar proper motions to other members in this star-forming complex. Of these five targets, four have optically thick (Class II) disks. On the one hand, this result resolves the conundrum of the puzzling low disk fraction in these clouds, while, on the other hand, it further clarifies the need to confirm the Spitzer selected diskless population with other tracers, especially in regions at low galactic latitude like Lupus V and VI. The use of Gaia astrometry is now an independent and reliable way to further assess the membership of candidate YSOs in these, and potentially other, star-forming regions