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"Patel, M. R."
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Transport processes induced by metastable boiling water under Martian surface conditions
2016
Liquid water on the Martian surface is expected to be metastable owing to low atmospheric pressure. Experiments at Martian conditions reveal that water and briny flows induce grain saltation and slope destabilization, with geomorphic consequences.
Liquid water may exist on the Martian surface today, albeit transiently and in a metastable state under the low atmospheric surface pressure
1
,
2
. However, the identification of liquid water on Mars from observed morphological changes is hampered by our limited understanding of how metastable liquids interact with sediments. Here, we present lab experiments in which a block of ice melts and seeps into underlying sediment, and the resulting downslope fluid propagation and sediment transport are tracked. In experiments at Martian surface pressure, we find that pure water boils as it percolates into the sediment, inducing grain saltation and leading to wholesale slope destabilization: a hybrid flow mechanism involving both wet and dry processes. For metastable brines, which are more stable under Martian conditions than pure water, saltation intensity and geomorphological impact are reduced; however, we observed channel formation in some briny flow experiments that may be analogous to morphologies observed on Mars. In contrast, under terrestrial-like experimental conditions, there is little morphological impact of seeping water or brine, which are both stable. We propose that the hybrid flow mechanism operating in our experiments under Martian surface pressure could explain observed Martian surface changes that were originally interpreted as the products of either dry or wet processes.
Journal Article
The formation of araneiforms by carbon dioxide venting and vigorous sublimation dynamics under martian atmospheric pressure
by
McElwaine, J. N.
,
Mc Keown, Lauren
,
Bourke, M. C.
in
704/445/125
,
704/445/845
,
Atmospheric pressure
2021
The local redistribution of granular material by sublimation of the southern seasonal
CO
2
ice deposit is one of the most active surface shaping processes on Mars today. This unique geomorphic mechanism is hypothesised to be the cause of the dendritic, branching, spider-like araneiform terrain and associated fans and spots—features which are native to Mars and have no Earth analogues. However, there is a paucity of empirical data to test the validity of this hypothesis. Additionally, it is unclear whether some araneiform patterns began as radial and then grew outward, or whether troughs connected at mutual centres over time. Here we present the results of a suite of laboratory experiments undertaken to investigate if the interaction between a sublimating
CO
2
ice overburden containing central vents and a porous, mobile regolith will mobilise grains from beneath the ice in the form of a plume to generate araneiform patterns. We quantify the branching and area of the dendritic features that form. We provide the first observations of plume activity via
CO
2
sublimation and consequent erosion to form araneiform features. We show that
CO
2
sublimation can be a highly efficient agent of sediment transport under present day Martian atmospheric pressure and that morphometry is governed by the Shields parameter.
Journal Article
Strong Localized Pumping of Water Vapor to High Altitudes on Mars During the Perihelion Season
2024
Here we present water vapor vertical profiles observed with the ExoMars Trace Gas Orbiter/Nadir and Occultation for MArs Discovery instrument during the perihelion and Southern summer solstice season (LS = 240°–300°) in three consecutive Martian Years 34, 35, and 36. We show the detailed latitudinal distribution of H2O at tangent altitudes from 10 to 120 km, revealing a vertical plume at 60°S–50°S injecting H2O upward, reaching abundance of about 50 ppmv at 100 km. We have observed this event repeatedly in the three Martian years analyzed, appearing at LS = 260°–280° and showing inter‐annual variations in the magnitude and timing due to long term effects of the Martian Year 34 Global Dust Storm. We provide a rough estimate of projected hydrogen escape of 3.2 × 109 cm−2 s−1 associated to these plumes, adding further evidence of the key role played by the perihelion season in the long term evolution of the planet's climate. Plain Language Summary Studying the vertical distribution of the Martian atmosphere is crucial to understand what happened to the water presumably present in larger abundance on ancient Mars. We have analyzed the vertical profiles of three Martian Years during the Southern summer, revealing a strong vertical transport of water vapor to the upper atmosphere. This seasonal phenomenon seems to be repeated annually, although with variations in the location and time of the year. Our estimation of the associated upward hydrogen flux represents an important loss which could have contributed to the escape of water to space for at least the period in which Mars had its present orbital inclination. Key Points Latitudinal distributions of water vapor up to 120 km are analyzed in detail using Nadir and Occultation for MArs Discovery (NOMAD) observations with an improved retrieval scheme Water vapor injection during the perihelion localized around 50°–60°S in three consecutive Martian years Martian year 34 Global Dust Storm may have affected the driving mechanisms of the plume, delaying its appearance and reducing its magnitude
Journal Article
Hemato-biochemical and ultrasonographic evaluation of hepatic lipidosis in dairy buffaloes
2022
Abstract Around 60% dairy animals developed moderate to severe hepatic lipidosis at the time of parturition or during early lactation stage. Most of clinician suspect the hepatic lipidosis during above time window only. However, negative energy balance or feeding of high concentrate diet can lead to hepatic lipidosis at any phase of life. The aim of the present study was to evaluate the potential for diagnosis of hepatic lipidosis by means of hemato-biochemical parameters and ultrasonography of the liver at any stage of life. Here, ultrasonographic back fat thickness measurement was correlated with ultrasonographic features of hepatic lipidosis. A total 60 buffaloes were included under the study and sampled for hematological and biochemical parameters. Hematological parameters did not exhibit any significant difference between healthy and hepatic lipidosis-affected buffaloes. Biochemical parameters like beta hydroxy butyric acid, non esterified fatty acid, aspartate amino transferase, gamma glutamyl transferase and alkaline phosphatase revealed a significant increase, while triglyceride, cholesterol, and glucose declined significantly in hepatic lipidosis-affected buffaloes. Total protein, albumin, and total bilirubin levels did not exhibit any significant difference. Based on ultrasonographic findings, the hepatic lipidosis-affected buffaloes were further sub divided into mild, moderate, and severe groups. Portal vein diameter and depth of portal vein were also estimated in current study. Ultrasonographic examination could diagnose 53.33% hepatic lipidosis cases in buffaloes. Among it, 37.50% buffalo had mild hepatic lipidosis, 33.33% had moderate hepatic lipidosis, and 29.16% had severe hepatic lipidosis. Depth of portal vein significantly increased in hepatic lipidosis cases. However, portal vein diameter exhibited a non-significant difference in mild, moderate, and severe groups of hepatic lipidosis. Back fat thickness also revealed a non-significant difference in mild, moderate, and severe hepatic lipidosis. Above study indicate that B mode ultrasonography of the liver can be employed to differentiate various grades of hepatic lipidosis in buffaloes. Biochemical parameters like NEFA, BHBA, AST, GGT, ALP, TG, cholesterol, and glucose can be helpful to screen the hepatic lipidosis at farm level.
Journal Article
Estimating the real-world performance of the PROMISE minimal-risk tool
2021
Stable chest pain is a common indication for cardiac catheterization. We assessed the prognostic value of the Prospective Multicenter Imaging Study for Evaluation (PROMISE) Minimal-Risk Tool in identifying patients who are at very low risk of obstructive coronary artery disease (CAD) or downstream cardiovascular adverse outcomes.
We applied the PROMISE Minimal-Risk Tool to consecutive patients without known CAD who underwent elective cardiac catheterization for stable angina from January 1, 2000 to December 31, 2014 in the Duke Databank for Cardiovascular Disease (DDCD). Patients with scores >0.46 (top decile of lowest-risk from the PROMISE cohort) were classified as low-risk. Logistic regression modeling compared likelihood of freedom from obstructive coronary artery disease on index angiography, 2-year survival, and 2-year survival free of myocardial infarction (MI) and MI/revascularization between low- and non low-risk patients. Alternative cut points to define low- risk patients were also explored.
Among 6251 patients undergoing cardiac catheterization for stable chest pain, 1082 (17.3%) were low-risk per the PROMISE minimal-risk tool. Among low risk patients, obstructive coronary artery disease was observed in 14.9% and left main disease (≥ 50% Stenosis) was rare (0.9%). Compared with other patients, low risk patients had a higher likelihood of freedom from obstructive coronary disease on index catheterization (85.1% vs. 44.2%, OR 4.84, 95% CI 4.06-5.77). Low risk patients had significantly higher survival (98.2% vs. 94.4%, OR 3.18, 95% CI 1.99-5.08), MI-free survival (97.2% vs. 91.9%, OR 3.03, 95% CI 2.07-4.45), and MI/revascularization-free survival (86.2 vs. 59.9%, OR 4.19, 95% CI 3.48-5.05) at 2 years than non-low risk patients. Operating characteristics for predicting the outcomes of interest varied modestly depending on the low-risk cut-point used but the positive predictive value for 2 year freedom from death was >98% regardless.
The PROMISE minimal-risk tool identifies 17% of stable chest pain patients referred to cardiac catheterization as low risk. These patients have a low prevalence of obstructive CAD and better survival than non-low risk patients. While this suggests that these patients are unlikely to benefit from catheterization, further research is needed to confirm a favorable downstream prognosis with medical management alone.
Journal Article
Increasing the Protein Content of Ice Cream
by
Patel, M. R
,
Acharya, M. R
,
Baer, R. J
in
administration & dosage
,
analysis
,
Animal productions
2006
Vanilla ice cream was made with a mix composition of 10.5% milk fat, 10.5% milk SNF, 12% beet sugar, and 4% corn syrup solids. None of the batches made contained stabilizer or emulsifier. The control (treatment 1) contained 3.78% protein. Treatments 2 and 5 contained 30% more protein, treatments 3 and 6 contained 60% more protein, and treatments 4 and 7 contained 90% more protein compared with treatment 1 by addition of whey protein concentrate or milk protein concentrate powders, respectively. In all treatments, levels of milk fat, milk SNF, beet sugar, and corn syrup solids were kept constant at 37% total solids. Mix protein content for treatment 1 was 3.78%, treatment 2 was 4.90%, treatment 5 was 4.91%, treatments 3 and 6 were 6.05%, and treatments 4 and 7 were 7.18%. This represented a 29.89, 60.05, 89.95, 29.63, 60.05, and 89.95% increase in protein for treatment 2 through treatment 7 compared with treatment 1, respectively. Milk protein level influenced ice crystal size; with increased protein, the ice crystal size was favorably reduced in treatments 2, 4, and 5 and was similar in treatments 3, 6, and 7 compared with treatment 1. At 1 wk postmanufacture, overall texture acceptance for all treatments was more desirable compared with treatment 1. When evaluating all parameters, treatment 2 with added whey protein concentrate and treatments 5 and 6 with added milk protein concentrate were similar or improved compared with treatment 1. It is possible to produce acceptable ice cream with higher levels of protein.
Journal Article
Different cellular p16INK4a localisation may signal different survival outcomes in head and neck cancer
2012
Background:
Recently, the management of head and neck squamous cell carcinoma (HNSCC) has focused considerable attention on biomarkers, which may influence outcomes. Tests for human papilloma infection, including direct assessment of the virus as well as an associated tumour suppressor gene p16, are considered reproducible. Tumours from familial melanoma syndromes have suggested that nuclear localisation of p16 might have a further role in risk stratification. We hypothesised p16 staining that considered nuclear localisation might be informative for predicting outcomes in a broader set of HNSCC tumours not limited to the oropharynx, human papilloma virus (HPV) status or by smoking status.
Methods:
Patients treated for HNSCC from 2002 to 2006 at UNC (University of North Carolina at Chapel Hill) hospitals that had banked tissue available were eligible for this study. Tissue microarrays (TMA) were generated in triplicate. Immunohistochemical (IHC) staining for p16 was performed and scored separately for nuclear and cytoplasmic staining. Human papilloma virus staining was also carried out using monoclonal antibody E6H4. p16 expression, HPV status and other clinical features were correlated with progression-free (PFS) and overall survival (OS).
Results:
A total of 135 patients had sufficient sample for this analysis. Median age at diagnosis was 57 years (range 20–82), with 68.9% males, 8.9% never smokers and 32.6% never drinkers. Three-year OS rate and PFS rate was 63.0% and 54.1%, respectively. Based on the p16 staining score, patients were divided into three groups: high nuclear, high cytoplasmic staining group (HN), low nuclear, low cytoplasmic staining group (LS) and high cytoplasmic, low nuclear staining group (HC). The HN and the LS groups had significantly better OS than the HC group with hazard ratios of 0.10 and 0.37, respectively, after controlling for other factors, including HPV status. These two groups also had significantly better PFS than the HC staining group. This finding was consistent for sites outside the oropharynx and did not require adjustment for smoking status.
Conclusion:
Different p16 protein localisation suggested different survival outcomes in a manner that does not require limiting the biomarker to the oropharynx and does not require assessment of smoking status.
Journal Article
Ferrofluid Based Squeeze Film Lubrication between Rough Stepped Plates with Couple Stress Effect
by
Patel, R. M.
,
Vashi, Y. D.
,
Deheri, G. M.
in
Bearing strength
,
Carrying capacity
,
Computational fluid dynamics
2018
This investigation purposes to study the magnetic fluid based squeeze film behavior on transversely rough stepped plates with the influence of couple stress. Using the well-known stochastic model of Christensen and Tonder the roughness effect has been evaluated. The magnetic fluid flow model of Neuringer - Roseinweig has been adopted to obtain the influence of magnetization. The governing Reynolds’ type equation is derived on the basis of stokes microcontinum theory for couple stress fluid. For the expression of pressure distribution, the stochastically averaged Reynolds’ type equation is solved. which results in calculation of load carrying capacity. The graphical outcomes also presented in tabular form suggest that although the bearing suffers on account of roughness, the magnetization and couple stress effect save the situation, as this combination does not allow the load carrying capacity to fall rapidly. However, in the case of negatively skewed roughness the magnetization goes a long way in dropping the adversarial influence of roughness by selecting an appropriate value of couple stress parameter when variance (-ve) is involved. It is found that the couple stress effect, alone may not be sufficient to counter the negative influence of transverse roughness and porosity. However, in almost all situations the ferrofluid lubrication adds significantly to the positive effect of couple stress to overcome the adversarial outcome of porosity and roughness. Further, the position of step plays a vital role for an all-round enhancement of the bearing performance.
Journal Article
Detection of green line emission in the dayside atmosphere of Mars from NOMAD-TGO observations
2020
The oxygen emission at 557.7 nm is a ubiquitous component of the spectrum of the terrestrial polar aurora and the reason for its usual green colour
1
. It is also observed as a thin layer of glow surrounding the Earth near 90 km altitude in the dayside atmosphere
2
,
3
but it has so far eluded detection in other planets. Here we report dayglow observations of the green line outside the Earth. They have been performed with the Nadir and Occultation for Mars Discovery ultraviolet and visible spectrometer instrument on board the European Space Agency’s ExoMars Trace Gas Orbiter. Using a special observation mode, scans of the dayside limb provide the altitude distribution of the intensity of the 557.7 nm line and its variability. Two intensity peaks are observed near 80 and 120 km altitude, corresponding to photodissociation of CO
2
by solar Lyman α and extreme ultraviolet radiation, respectively. A weaker emission, originating from the same upper level of the oxygen atom, is observed in the near ultraviolet at 297.2 nm. These simultaneous measurements of both oxygen lines make it possible to directly derive a ratio of 16.5 between the visible and ultraviolet emissions, and thereby clarify a controversy between discordant ab initio calculations and atmospheric measurements that has persisted despite multiple efforts. This ratio is considered a standard for measurements connecting the ultraviolet and visible spectral regions. This result has consequences for the study of auroral and airglow processes and for spectral calibration.
The oxygen emission at 557.7 nm, responsible for the green colour of auroras on Earth, is present in two layers at 80 and 120 km altitude on the dayside atmosphere of Mars. Simultaneous observations of the oxygen both in this visible line and in the ultraviolet could also constrain the elusive visible/ultraviolet intensity ratio of the auroral emission to a value of 16.5.
Journal Article
Design and rationale for the Effects of Ticagrelor and Clopidogrel in Patients with Peripheral Artery Disease (EUCLID) trial
by
Baumgartner, Iris
,
Fowkes, F. Gerry
,
Held, Peter
in
Acute coronary syndromes
,
Adenosine - administration & dosage
,
Adenosine - adverse effects
2016
Despite overwhelming data demonstrating the efficacy of antiplatelet therapy in heart disease and stroke, data in peripheral artery disease (PAD) are less compelling. Aspirin has modest evidence supporting a reduction in cardiovascular events in patients with PAD, whereas clopidogrel monotherapy may be more effective in PAD. Ticagrelor, a potent, reversibly binding P2Y12 receptor antagonist, is beneficial in patients with acute coronary syndrome and prior myocardial infarction. The EUCLID trial is designed to address the need for effective antiplatelet therapy in PAD to decrease the risk of cardiovascular events.
EUCLID is a randomized, double-blind, parallel-group, multinational clinical trial designed to evaluate the efficacy and safety of ticagrelor compared with clopidogrel for the prevention of major adverse cardiovascular events in subjects with symptomatic PAD. Subjects with established PAD will be randomized in a 1:1 fashion to ticagrelor 90 mg twice daily or clopidogrel 75 mg daily. The primary end point is a composite of cardiovascular death, myocardial infarction, or ischemic stroke. Other end points address limb events including acute leg ischemia, need for revascularization, disease progression by ankle-brachial index, and quality of life. The primary safety objective is Thrombolysis in Myocardial Infarction–defined major bleeding. Recruitment began in December 2012 and was completed in March 2014; 13,887 patients were randomized. The trial will continue until at least 1,364 adjudicated primary end points occur.
The EUCLID study is investigating whether treatment with ticagrelor versus clopidogrel, given as antiplatelet monotherapy, will reduce the incidence of cardiovascular and limb-specific events in patients with symptomatic PAD.
Journal Article