Correlation Between Volume and Pressure of Intracranial Space With Craniectomy Surface Area and Brain Herniation: A Phantom-Based Study.

There are proponents of decompressive craniectomy (DC) and its various modifications who claim reasonable clinical outcomes for each of them. Clinical outcome in cases of traumatic brain injury, managed conservatively or aided by different surgical techniques, depends on multiple factors, which vary widely among patients and have complex interplay, making it difficult to compare one case with another in absolute terms. This forms the basis of the perceived necessity to have a standard model to study, compare, and strategize in this field. We designed a phantom-based model and present the findings of the study aimed at establishing a correlation of the volume of intracranial space and changes in intracranial pressure (ICP) with surface area of the craniectomy defect created during DC and brain herniation volume. A roughly hemispherical radio-opaque container was scanned on a 128-slice computed tomography scanner. Craniectomies of different sizes and shapes were marked on the walls of the phantom. Two spherical sacs of stretchable materials were subsequently placed inside the phantom, fixed to three-way connectors, filled with water, and connected with transducers. The terminals of the transducer cables were coupled with the display monitor through a signal amplifier and processor module. Parts of the wall of the phantom were removed to let portions of the sac herniate through the defect, simulating a DC. Volume measurements using AW volume share 7® software were done. Resection of a 12.7 × 11.5 cm part of the wall resulted in a 10-cm-diameter defect in the wall. Volume differential of 35 mL created a midline shift of 5 mm to the side with lesser volume. When measuring pressure in two stretchable sacs contained inside the phantom, there always remained a pressure differential ranging from 1 to 2 mm Hg in different recordings, even with sacs on both sides containing an equal volume of fluids. Creating a circular wall defect of 10 cm in diameter with an intracavitary pressure of 35 mm Hg on the ipsilateral sac and 33 mm on the contralateral sac recorded with intact walls, resulted in a true volume expansion of 48.411 cm3. The herniation resulted in a reduction of pressure in both sacs, with the pressure recorded as 25 mm in the ipsilateral sac and 24 mm in the contralateral sac. The findings closely matched those of the other model-based studies. Refinement of the materials used is likely to provide a valid platform to study cranial volume, ICP, craniectomy size, and brain prolapse volume in real time. The model will help in pre-operatively choosing the most appropriate technique between a classical DC, a hinge craniotomy, and an expansive cranioplasty technique in cases of refractory raised ICP.

Limestone and yellow gypsum can reduce cadmium accumulation in groundnut (Arachis hypogaea): A study from a three-decade old landfill site.

Cadmium (Cd) toxicity has cropped up as an important menace in the soil-plant system. The use of industrial by-products to immobilise Cd in situ in polluted soils is an interesting remediation strategy. In the current investigation, two immobilizing amendments of Cd viz., Limestone (traditionally used) and Yellow gypsum (industrial by-product) have been used through a green-house pot culture experiment. Soil samples were collected from four locations based on four graded levels of DTPA extractable Cd as Site 1 (0.43 mg kg-1), Site 2 (0.92 mg kg-1), Site 3 (1.77 mg kg-1) and Site 4 (4.48 mg kg-1). The experiment was laid out in a thrice replicated Factorial Complete Randomized Design, with one factor as limestone (0, 250, 500 mg kg-1) and the other being yellow gypsum (0, 250, 500 mg kg-1) on the collected soils and groundnut was grown as a test crop. Results revealed that the DTPA-extractable Cd content in soil and Cd concentration in plants decreased significantly with the increasing doses of amendments irrespective of initial soil available Cd and types of amendment used. The effect of amendment was soil specific and in case of Site 1 (low initial Cd) the effect was more prominent. The reduction in DTPA-extractable Cd in combined application of limestone and yellow gypsum @500 mg kg-1 over the absolute control in soil under groundnut for the sites was by far the highest with the values of 83.72%, 77.17%, 48.59% and 40.63% respectively. With the combined application, Target Cancer Risk (TCR) of Cd was also reduced. Hence, combined application of limestone and yellow gypsum can be beneficial in the long run for mitigating Cd pollution.

Isolation and characterization of rhizobacteria from lentil for arsenic resistance and plant growth promotion.

Low-cost microbial remediation strategies serve as a viable and potent weapon for curbing the arsenic menace. In the present study, two arsenic-resistant bacteria were isolated from the contaminated lentil rhizosphere in Gangetic plain of eastern India. LAR-21 (Burkholderia cepacia, MW356875) and LAR-25 (Burkholderia cenocepacia, MW356894) could remove 87.6% and 85.9% of arsenite (10 mM) from the liquid culture medium in laboratory condition. They were highly resistant to arsenate and arsenite and also had a high arsenite oxidase activity. LAR-21 showed the highest level of minimum inhibitory concentration value of 390 mM for arsenate and 31 mM for arsenite. The same strain was found to show highest arsenite oxidase activity, i.e., 5.2 nM min-1 mg-1of protein. These two strains further possess potential plant growth-promoting characteristics like indole acetic acid production (5-15 mM IAA mL-1), 1-aminocyclopropane-1-carboxylate deaminase (8-21 nM α-keto butyrate mg protein-1 h-1), nitrogenase activity (3-8.99 nM ethylene mg cell protein-1 h-1), siderophore production (17-22.1 µM deferoxamine mesylate mL-1), phosphate solubilization (261-453 µg mL-1) under arsenic stress condition. The plant growth promotion of the strains was further validated by pot study of lentil by assessing their agronomic and growth-related traits, and potential to recover from arsenic stress (17.2-21.2% arsenic reduction in root and shoot, 16-19.2% in leaf and pod, and 15-23% reduction in seeds). The LAR-21 strain, thus, emerged as the most suited candidate for bioremediation and plant (lentil) growth promotion in arsenic polluted environment.

Step Ladder Expansive Cranioplasty: A Novel Perspective in Cranial Volume Augmentation Surgery.

Background In face of a refractory raised intracranial pressure (ICP), surgeons most commonly resort to decompressive craniectomy (DC). Procedure leaves an unprotected brain underlying the craniectomy defect and Monro-Kellie doctrine: disrupted. Different variants of hinge craniotomies (HC) have been used with clinical outcomes comparable to DC as single stage alternatives. However, both DC and every variant of HC have a limit to the achievable volume augmentation and all invariably cause a compression of the cerebral cortex and its vasculature at the craniotomy site. We believe both these limitations adversely affect the outcome. Methods A team of neuroscientists in Indian Armed Forces Medical Services has been working for the last 9 years toward developing a novel surgical technique that can mitigate both these drawbacks. Desired procedure should take the centripetal pressure exerted by the combination of the tensile strength of the scalp (with or, without an underlying bone flap) and atmospheric pressure off the brain surface while achieving an assured augmentation of intracranial volume that can be optimized on a case-to-case basis. We call it a "step ladder expansive cranioplasty." Results The distance of the parietal eminence was found to have increased by 10.2 mm on the operated side after expansive cranioplasty. Conclusion From drawing board to bedside, we have made some progress toward our goal, but it is still far away from completion. More studies are required to fill in the gaps in our knowledge necessary to optimize the various parameters of the surgery. Procedure has promise to be of special role in in war and disaster scenarios.

Determination of bioavailable arsenic threshold and validation of modeled permissible total arsenic in paddy soil using machine learning.

Minimizing arsenic intake from food consumption is a key aspect of the public health response in arsenic (As)-contaminated regions. In many of these regions, rice is the predominant staple food. Here, we present a validated maximum allowable concentration of total As in paddy soil and provide the first derivation of a maximum allowable soil concentration for bioavailable As. We have previously used meta-analysis to predict the maximum allowable total As in soil based on decision tree (DT) and logistic regression (LR) models. The models were defined using the maximum tolerable concentration (MTC) of As in rice grains as per the codex recommendation. In the present study, we validated these models using three test data sets derived from purposely collected field data. The DT model performed better than the LR in terms of accuracy and Matthews correlation coefficient (MCC). Therefore, the DT estimated maximum allowable total As in paddy soil of 14 mg kg-1 could confidently be used as an appropriate guideline value. We further used the purposely collected field data to predict the concentration of bioavailable As in the paddy soil with the help of random forest (RF), gradient boosting machine (GBM), and LR models. The category of grain As (MTC) was considered as the dependent variable; bioavailable As (BAs), total As (TAs), pH, organic carbon (OC), available phosphorus (AvP), and available iron (AvFe) were the predictor variables. LR performed better than RF and GBM in terms of accuracy, sensitivity, specificity, kappa, precision, log loss, F1score, and MCC. From the better-performing LR model, bioavailable As (BAs), TAs, AvFe, and OC were significant variables for grain As. From the partial dependence plots (PDP) and individual conditional expectation (ICE) of the LR model, 5.70 mg kg-1 was estimated to be the limit for BAs in soil.

Effect of radiation-reaction on charged particle dynamics in a focused electromagnetic wave.

The effect of radiation-reaction force on the dynamics of a charged particle in an intense focused light wave is investigated using the physically appealing Hartemann-Luhmann equation of motion. It is found that, irrespective of the choice of initial conditions, radiation reaction force causes the charged particle to cross the focal region, provided the particle is driven into regions where the radiation reaction force dominates over the Lorentz force, thus enhancing the forward energy gained by the particle from the intense light wave. This result is in sharp contrast to the well known result, derived in the absence of radiation reaction forces, where for certain initial conditions the particle reflects from the high intensity region of the focused light wave, thereby losing forward energy. From the perspective of energy gain, our studies clearly show that the parameter space for forward energy gain which is reduced by ponderomotive effects is compensated by radiation reaction effects. These results, which are of relevance to the present day direct laser acceleration schemes of charged particle, also agrees with that obtained using the well known Landau-Lifshitz equation of motion.

Recent advances in the bioremediation of arsenic-contaminated soils: a mini review.

The carcinogenic metalloid arsenic (As), owing to its persistent behavior in elevated levels in soils, aggravates environmental and human health concerns. The current strategies used in the As decontamination involve several physical and chemical approaches. However, it involves high cost and even leads to secondary pollution. Therefore, it is quite imperative to explore methods that can eradicate As menace from the environment in an eco-friendly, efficient, and cost-competitive way. Searching for such viable alternatives leads to the option of bioremediation technology by utilizing various microorganisms, green plants, enzymes or even their integrated methods. This review is intended to give scientific and technical details about recent advances in the bioremediation strategies of As in soil. It takes into purview the extent, toxicological manifestations, pathways of As exposure and exemplifies the substantive need of bioremediation technologies such as phytoremediation and biosorption in a descriptive manner. Additionally, the paper looks into the wide potential of some plant growth promoting microorganisms (PGPMs) that improve plant growth on one hand and alleviate As toxicity on the other. Furthermore, it also makes a modest attempt to assimilate the use of nanoparticles, non-living biomass and transgenic crops which are the emerging alternative bioremediation technologies.

Complexation, retention and release pattern of arsenic from humic/fulvic acid extracted from zinc and iron enriched vermicompost.

Arsenic (As) is a highly poisonous heavy metal with major environmental ramifications. Inorganic components such as zinc (Zn) and iron (Fe), as well as organic vermicompost, have been used as management solutions, with limited attempts of using them together. The current study involved preparing non-enriched vermicompost as well as six distinct Zn and Fe enriched vermicomposts and analyzing their chemical composition using the standard procedures. Organic fractions from these seven vermicompost and arsenic polluted soils of West Bengal, India were recovered and separated into humic (HA) and fulvic acid (FA) fractions. Potentiometric titrations, viscometric assays, and visible spectrophotometry were used to characterize the HA and FA samples. In aqueous phase the stability constant (log K) of the complexes formed with As indicates that stability of FA extracted from enriched vermicompost V4 (Zn and Fe sulphate @ 10% w/w dry weight basis of composting substrates before application of vermiworms) was maximum as 10.20 with a mole ratio (x) value of 1.36. Fourier-transform infrared (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM) studies confirmed the complexation of As with HA/FA. The release isotherm of As from the HA/FA complexes in the presence of competitive oxy-anions was found to follow the order of sulphate > nitrate > phosphate.

Investigation of arsenic-resistant, arsenite-oxidizing bacteria for plant growth promoting traits isolated from arsenic contaminated soils.

The problem of arsenic (As) pollution being severe warrants opting for low-cost microbial remediation strategies. The present study of identifying suitable bacterial strains led to the isolation of eleven As-tolerant strains from the As-contaminated rhizosphere soils of West Bengal, India. They were found to oxidize/reduce 55-31.6% of 5 mM As(III) and 73-37.6% of 5 mM As(V) within 12 h. The four isolates (BcAl-1, JN 73, LAR-2, and AR-30) had a high level of As(III) oxidase activity along with a higher level of As(V) and As(III) resistance. The agar diffusion assay of the isolates further confirmed their ability to endure As stress. The presence of aoxB gene was observed in these four As(III) oxidizing isolates. Evaluation of plant growth-promoting characteristics revealed that BcAl-1 (Burkholderia cepacia), JN 73 (Burkholderia metallica), AR-30 (Burkholderia cenocepacia), and LAR-2 (Burkholderia sp.) had significant plant growth-promoting characteristics (PGP), including the ability to solubilize phosphate, siderophore production, indole acetic acid-like molecules production, ACC deaminase production, and nodule formation under As stressed condition. BcAl-1 and JN 73 emerged as the most promising traits in As removal as well as plant growth promotion.

Characterization and risk assessment of arsenic contamination in soil-plant (vegetable) system and its mitigation through water harvesting and organic amendment.

Field experiments with vegetables [cauliflower (Brassica oleracea var. botrytis), tomato (Solanum lycopersicum) and spinach (Spinacia oleracea)] were conducted at geogenically arsenic-contaminated Ghentugachi village in West Bengal, India, for two consecutive years to study arsenic accumulation by the selected vegetables and to explore the efficiencies of use of harvested/harnessed water and organic amendments (Mustard Cake, Vermicompost and Farm Yard Manure) in reducing arsenic load in soil-plant system. Results revealed that arsenic accumulations in the cauliflower head, spinach leaf and tomato fruit were in the range of 0.15-0.17, 2.73-3.00 and 0.08 mg kg-1. Organic amendment and pond water irrigation when applied either separately or together were found to be effective in reducing arsenic contamination in soil-plant system compared to irrigation with shallow tube well-drafted underground water. Vermicompost remained most successful among the organic amendments. Conjunctive use of surface (pond) and ground water also significantly reduced the level of arsenic in the system. The risk of dietary intake of arsenic through the selected vegetables was computed through % Provisional Tolerable Weekly Intake, Hazard Quotient and Target Cancer Risk. Cauliflower and tomato were found safe in the individual contribution to food chain, while consumption of spinach leaf (possessing 10.4-22.6% more arsenic than maximum tolerable limits) remained unsafe in all dietary risk measures.

Magnetic turbulence in a table-top laser-plasma relevant to astrophysical scenarios.

Turbulent magnetic fields abound in nature, pervading astrophysical, solar, terrestrial and laboratory plasmas. Understanding the ubiquity of magnetic turbulence and its role in the universe is an outstanding scientific challenge. Here, we report on the transition of magnetic turbulence from an initially electron-driven regime to one dominated by ion-magnetization in a laboratory plasma produced by an intense, table-top laser. Our observations at the magnetized ion scale of the saturated turbulent spectrum bear a striking resemblance with spacecraft measurements of the solar wind magnetic-field spectrum, including the emergence of a spectral kink. Despite originating from diverse energy injection sources (namely, electrons in the laboratory experiment and ion free-energy sources in the solar wind), the turbulent spectra exhibit remarkable parallels. This demonstrates the independence of turbulent spectral properties from the driving source of the turbulence and highlights the potential of small-scale, table-top laboratory experiments for investigating turbulence in astrophysical environments.

Breaking of upper hybrid oscillations in the presence of an inhomogeneous magnetic field.

We present space-time evolution of large-amplitude upper hybrid modes in a cold homogeneous plasma in the presence of an inhomogeneous magnetic field. Using the method of Lagrange variables, an exact space-time-dependent solution is obtained in parametric form. It is found that the magnetic field inhomogeneity causes various nonlinearly excited modes to couple, resulting in phase mixing and eventual breaking of the initially excited mode. The occurrence of wave breaking is seen by the appearance of spikes in the density profile. These results will be of relevance to laboratory and space plasma situations in which the external magnetic field is inhomogeneous.

Residual Bernstein-Greene-Kruskal-like waves after one-dimensional electron wave breaking in a cold plasma.

A one-dimensional particle in cell simulation of large amplitude plasma oscillations is carried out to explore the physics beyond wave breaking in a cold homogeneous unmagnetized plasma. It is shown that after wave breaking, all energy of the plasma oscillation does not end up as random kinetic energy of particles, but some fraction, which is decided by Coffey's wave breaking limit in warm plasma, always remains with two oppositely propagating coherent Bernstein-Greene-Kruskal like modes with supporting trapped particle distributions. The randomized energy distribution of untrapped particles is found to be characteristically non-Maxwellian with a preponderance of energetic particles.

Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas.

Turbulence in fluids is a ubiquitous, fascinating, and complex natural phenomenon that is not yet fully understood. Unraveling turbulence in high density, high temperature plasmas is an even bigger challenge because of the importance of electromagnetic forces and the typically violent environments. Fascinating and novel behavior of hot dense matter has so far been only indirectly inferred because of the enormous difficulties of making observations on such matter. Here, we present direct evidence of turbulence in giant magnetic fields created in an overdense, hot plasma by relativistic intensity (10(18) W/cm(2)) femtosecond laser pulses. We have obtained magneto-optic polarigrams at femtosecond time intervals, simultaneously with micrometer spatial resolution. The spatial profiles of the magnetic field show randomness and their k spectra exhibit a power law along with certain well defined peaks at scales shorter than skin depth. Detailed two-dimensional particle-in-cell simulations delineate the underlying interaction between forward currents of relativistic energy "hot" electrons created by the laser pulse and "cold" return currents of thermal electrons induced in the target. Our results are not only fundamentally interesting but should also arouse interest on the role of magnetic turbulence induced resistivity in the context of fast ignition of laser fusion, and the possibility of experimentally simulating such structures with respect to the sun and other stellar environments.

Breaking of longitudinal Akhiezer-Polovin waves.

The breaking of longitudinal Akhiezer-Polovin (AP) waves is demonstrated using a one-dimensional simulation based on the Dawson sheet model. It is found that the AP longitudinal waves break through the process of phase mixing at an amplitude well below the breaking amplitude for AP waves, when subjected to arbitrarily small longitudinal perturbations. Results from the simulation show a good agreement with the Dawson phase mixing formula modified to include relativistic mass variation effects. This result may be of direct relevance to the laser- or particle-beam plasma wakefield experiments.