The thyroid gland is an endocrine gland situated in the lower part of front and the sides of the neck. Thyroid nodules are very common with estimated prevalence that ranges from 4% by palpation to ...67% by Ultrasonography. The main purpose of our study was to detect cases of thyroid carcinoma preoperatively in patients with solitary thyroid nodules and subsequently advise surgery in these selected patients only, without missing any malignancy. The goal of the investigating modalities used was that they should detect maximum (ideally all) cases of carcinoma and minimize the number of patients who might end up with unnecessary surgery. The present study was to be undertaken for assessment of accuracy of FNAC & USG in relation to Histopathology in cases of solitary thyroid nodule (accuracy in terms of sensitivity, specificity, positive predictive value, negative predictive value). In our series of total 102 pateints, 90 patients were females (88.2%) and 12 cases were males (11.8%). The overall incidence of malignancy in solitary thyroid nodules is 15.68%. In our series the sensitivity and specificity of Fine needle aspiration cytology and Ultrasonography was 81.25% & 98.84% and 75% and 77.91% respectively. The closest method to ideal was fine needle aspiration cytology. However, a combination of techniques, rather than a single technique, give optimum results & avoid unnecessary surgery in a greater number of patients without missing any malignancy.
In patients with solitary thyroid nodules, the first course of action is to determine whether the nodule is benign or malignant. Many investigations are used to differentiate between benign and ...malignant nodules so as to avoid surgery in those who don’t need it. Among these, FNAC and USG are commonly used in association with clinical features but there are drawbacks of each technique. The present study was undertaken to assess the diagnostic effectivity of thyrotropin (also known as TSH) to thyroglobulin ratio in correlation with histopathology in euthyroid patients having solitary thyroid nodule. This is a prospective study carried out on 48 euthyroid cases of solitary thyroid nodule. All patients subjected to FNAC, USG, thyrotropin and thyroglobulin assay. Then, they underwent surgery and histopathological examination (HPE) of the specimens done. Finally, the histopathology reports were correlated with the thyrotropin to thyroglobulin ratio in order to evaluate their sensitivity and specificity by statistical methods. The sensitivity and specificity of thyrotropin to thyroglobulin ratio was 100% and 100% respectively. All malignant lesions according to thyrotropin to thyroglobulin ratio were confirmed by histopathology indicating its excellence. Therefore, TSH to thyroglobulin ratio helps in planning the correct management and avoids second surgery. It was found that serum TSH:Tg is a safe, reliable and effective diagnostic modality with a high sensitivity and specificity and is the single best investigation for preoperative evaluation of solitary thyroid nodule to differentiate between benign and malignant nodules.
COVID Associated Invasive Aspergillosis Bhandari, Sudhir; Gupta, Shubhangi; Bhargava, Shruti ...
Indian Journal of Otolaryngology and Head & Neck Surgery,
06/2023, Volume:
75, Issue:
2
Journal Article
Peer reviewed
Open access
To study the possible association between invasive fungal sinusitis (aspergillosis) and coronavirus disease. An observational study was conducted at a tertiary care centre over 6 months, involving ...all patients with aspergillosis of the paranasal sinuses suffering from or having a history of COVID-19 infection. 92 patients presented with aspergillosis, all had an association with COVID-19 disease. Maxillary sinus (100%) was the most common sinus affected. Intraorbital extension was seen in 34 cases, while intracranial extension was seen in 5 cases. Diabetes mellitus was present in 75 of 92 cases. All had a history of steroid use during their coronavirus treatment. New manifestations of COVID-19 are appearing over time. The association between coronavirus and aspergillosis of the paranasal sinuses must be given serious consideration. Uncontrolled diabetes and overzealous use of steroids are two main factors aggravating the illness, and both of these must be properly checked.
Cochlear Implantation in Pierre Robin Syndrome Gupta, Shubhangi; Dagur, Mukesh; Grover, Mohnish ...
Indian journal of otolaryngology, and head, and neck surgery,
09/2021, Volume:
73, Issue:
3
Journal Article
Peer reviewed
Open access
Hereditary hearing loss accounts for nearly 60% of deafness in developed countries and about 30% of them are syndromic. Pierre Robin Syndrome is one such condition. The patient with this syndrome ...usually presnts with triad of micrognathia, glossoptosis and cleft palate. Hearing loss is mostly conductive but there can be sensorineural hearing loss also. Here we present a case of Pierre Robin Syndrome who presented with congenital hearing loss. He also had bilateral serous otitis media. He underwent cochlear implant surgery and was prescribed antihistaminics and steroid spray for middle ear effusion. Therefore, proper clinical evaluation is required.
We present a hydro-geomechanical model for subsurface methane hydrate systems. Our model considers kinetic hydrate phase change and non-isothermal, multi-phase, multi-component flow in elastically ...deforming soils. The model accounts for the effects of hydrate phase change and pore pressure changes on the mechanical properties of the soil. It also accounts for the effect of soil deformation on the fluid-solid interaction properties relevant to reaction and transport processes (e.g., permeability, capillary pressure, and reaction surface area). We discuss a ’cause-effect’ based decoupling strategy for the model and present our numerical discretization and solution scheme. We then proceed to identify the important model components and couplings which are most vital for a hydro-geomechanical hydrate simulator, namely, (1) dissociation kinetics, (2) hydrate phase change coupled with non-isothermal two phase two component flow, (3) two phase flow coupled with linear elasticity (poroelasticity coupling), and finally (4) hydrate phase change coupled with poroelasticity (kinetics-poroelasticity coupling). To show the versatility of our hydrate model, we numerically simulate test problems where, for each problem, we methodically isolate one out of the four aforementioned model components or couplings. A special emphasis is laid on the kinetics-poroelasticity coupling for which we present a test problem where an axially loaded hydrate bearing sand sample experiences a spontaneous shift in the hydrate stability curve causing the hydrate to melt. For this problem, we present an analytical solution for pore-pressure, which we subsequently use to test the accuracy of the numerical scheme. Finally, we present a more complex 3
D
example where all the major model components are put together to give an idea of the model capabilities. The setting is based on a subsurface hydrate reservoir which is destabilized through depressurization using a low pressure gas well. In this example, we simulate the melting of hydrate, methane gas generation, and the resulting ground subsidence and stress build-up in the vicinity of the well.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The gas hydrate stability zone (GHSZ) is defined by pressure-temperature-salinity (pTS) constraints of natural gas hydrate (GH) system. It refers to a depth interval which usually extends several ...hundred meters into the sediment column at sufficient water depths. The lower boundary of the GHSZ often coincides in seismic reflection data with a bottom simulating reflector (BSR), which indicates the transition between the underlying free gas and the overlying no-free gas zone at the thermodynamic stability boundary. The GHSZ in geological systems is dynamic and can shift in response to sedimentation processes and/or changes in environmental conditions such as bottom water temperatures, hydrostatic pressure, and water salinity. The appearance of multiple BSRs has been interpreted as remnants of former GHSZ shifts which have persisted over geological timescales. In this study, we numerically simulate the sedimentation-driven development of multiple stacked BSRs in the Danube deep-sea fan in the Black Sea. We show that in this dynamic sediment depositional regime sufficient amounts of residual gas remain trapped in the former GHSZ, given sufficiently high initial gas hydrate saturations, so that paleo-BSRs could persist over long time scales (∼300 kyr). In particular, the formation and persistence of multiple BSRs in the Danube Delta is controlled by the sequence of sedimentation events of the levees induced by sea-level change. The kinetics of methane phase transitions between gas hydrate, dissolved methane, and free gas plays a key role in the coexistence, location and timing of the multiple BSRs. Thus, For a given permeability, distinct multiple BSRs appear only for a narrow range of GH formation (10−14<kfmol/m2Pas≤10−12) and dissociation rates (10−16<kdmol/m2Pas<10−14).
•This study simulates the sedimentation-driven development of multiple stacked BSRs in the Danube paleo-delta, Black Sea.•Multiple BSR formation in Black Sea is controlled by the sequence of sedimentation events of levees due to sea-level changes.•Kinetics of phase transitions plays a key role in the coexistence, location, and timing of the multiple BSRs.•Development of multiple BSRs is possible only under a narrow range of parameters, unique for the Danube delta setting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Subsurface flows, particularly hyporheic exchange fluxes, driven by streambed topography, permeability, channel gradient and dynamic flow conditions provide prominent ecological services such as ...nitrate removal from streams and aquifers. Stream flow dynamics cause strongly nonlinear and often episodic contributions of nutrient concentrations in river‐aquifer systems. Using a fully coupled transient flow and reactive transport model, we investigated the denitrification potential of hyporheic zones during peak‐flow events. The effects of streambed permeability, channel gradient and bedform amplitude on the spatio‐temporal distribution of nitrate and dissolved organic carbon in streambeds and the associated denitrification potential were explored. Distinct peak‐flow events with different intensity, duration and hydrograph shape were selected to represent a wide range of peak‐flow scenarios. Our results indicated that the specific hydrodynamic characteristics of individual flow events largely determine the average positive or negative nitrate removal capacity of hyporheic zones, however the magnitude of this capacity is controlled by geomorphological settings (i.e., channel slope, streambed permeability and bedform amplitude). Specifically, events with longer duration and higher intensity were shown to promote higher nitrate removal efficiency with higher magnitude of removal efficiency in the scenarios with higher slope and permeability values. These results are essential for better assessment of the subsurface nitrate removal capacity under the influence of flow dynamics and particularly peak‐flow events in order to provide tailored solutions for effective restoration of interconnected river‐aquifer systems.
Key Points
Reactive transport model predicts stream geomorphological impacts on hyporheic denitrification potential
High frequency observations of nutrient fluxes improve predictions of denitrification potential
Controls of duration and intensity of peak‐flow events on denitrification potential vary between geomorphological settings
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Alpine permafrost environments are highly vulnerable and sensitive to changes in regional and global climate trends. Thawing and degradation of permafrost has numerous adverse environmental, ...economic, and societal impacts. Mathematical modeling and numerical simulations provide powerful tools for predicting the degree of degradation and evolution of subsurface permafrost as a result of global warming. A particularly significant characteristic of alpine environments is the high variability in their surface geometry which drives large lateral thermal and fluid fluxes along topographic gradients. The combination of these topography-driven fluxes and unsaturated ground makes alpine systems markedly different from Arctic permafrost environments and general geotechnical ground freezing applications, and therefore, alpine permafrost demands its own specialized modeling approaches. In this work, we present a multi-physics permafrost model tailored to subsurface processes of alpine regions. In particular, we resolve the ice–water phase transitions, unsaturated conditions, and capillary actions, and account for the impact of the evolving pore space through freezing and thawing processes. Moreover, the approach is multi-dimensional, and therefore, inherently resolves the topography-driven horizontal fluxes. Through numerical case studies based on the elevation profiles of the Zugspitze (DE) and the Matterhorn (CH), we show the strong influence of lateral fluxes in 2D on active layer dynamics and the distribution of permafrost.
•A new numerical model for permafrost in alpine regions.•Importance of lateral fluxes in mountain permafrost modeling.•Influence of unsaturated conditions on freezing processes.•Development of mountain permafrost during warming scenario.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Semi-Implicit and Compound-fast MRT methods are proposed based on Implicit–Explicit approach.•Semi-Implicit MRT gives higher speed-up but lower accuracy compared to Compound-fast MRT.•Stability of ...Semi-Implicit MRT depends on the relative activity of the system-components.•Stability of Compound-fast MRT is relatively independent of the activity of the system-components.•Significant speed-up can be expected for complex 3D settings.
We present an extrapolation-based semi-implicit multi-rate time stepping (MRT) scheme and a compound-fast MRT scheme for a naturally partitioned, multi-time-scale hydro-geomechanical hydrate reservoir model. We evaluate the performance of the two MRT methods compared to an iteratively coupled solution scheme and discuss their advantages and disadvantages. The performance of the two MRT methods is evaluated in terms of speed-up and accuracy by comparison to an iteratively coupled solution scheme. We observe that the extrapolation-based semi-implicit method gives a higher speed-up but is strongly dependent on the relative time scales of the latent (slow) and active (fast) components. On the other hand, the compound-fast method is more robust and less sensitive to the relative time scales, but gives lower speed up as compared to the semi-implicit method, especially when the relative time scales of the active and latent components are comparable.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Gas hydrates are one of the largest marine carbon reservoirs on Earth. The conventional understanding of hydrate dynamics assumes that the system, in the absence of external triggers, converges to a ...steady-state over geological time-scales, achieving fixed concentrations of gas hydrate and free gas phase. However, using a high-fidelity numerical model and consistently resolving phase states across multiple fluid-fluid and fluid-solid phase boundaries, we have identified well-defined periodic states embedded within hydrate system dynamics. These states lead to cyclic formation and dissolution of massive hydrate layers that is self-sustaining for the majority of natural marine settings. This previously unresolved characteristic could manifest as spontaneous gas migration and pressure release in, supposedly, unperturbed systems. Our findings show that the gas hydrate systems are not bound to have unique steady-state solutions. Instead, existence of periodic states introduces an irreducible, but, quantifiable uncertainty in gas hydrate dynamics which adds significant error bars to global gas hydrate inventory estimates.
•Well-defined periodic states are embedded within the steady-state hydrate dynamics.•Periodic states lead to cyclic formation and dissociation of massive hydrate layers.•Periodic states are fully self-sustaining even in the absence of external triggers.•Spontaneous gas migration & pressure release occur in supposedly unperturbed systems.•Existence of periodic states implies an irreducible uncertainty in hydrate dynamics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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