Water chemistry reconnaissance geochemical modeling in the Meadow Valley Wash area, southern Nevada

Online access for this thesis was created in part with support from the Institute of Museum and Library Services (IMLS) administered by the Nevada State Library, Archives and Public Records through the Library Services and Technology Act (LSTA). To obtain a high quality image or document please contact the DeLaMare Library at https://unr.libanswers.com/ or call: 775-784-6945.The study area groundwater system encompasses Coyote Springs, Kane Springs, Moapa and Meadow Valleys. The geology is dominated by Paleozoic carbonates to the north, and younger alluvium and lacustrine deposits to the south. Underflow from Pahranagat Valley mixes with groundwater from Kane Springs Wash and recharge from the Sheep Range to produce the final discharge of Muddy Springs at the head of Moapa Valley. It is possible that at least 4,000 acre- ft/yr of underflow from Meadow Valley Wash contributes to Muddy Spring discharge. The use of BALANCE, WATEQ, and PHREEQE chemically verifies these proposed flowpaths. Volcanic rocks are the probable explanation of sodium-dominated waters in the south. In lower Moapa Valley and Meadow Valley Wash, the Muddy Creek Formation produces saline, generally sodium-sulfate waters (up to 4500 mg/1 TDS) by dissolution of evaporite minerals, primarily gypsum and thenardite. Flow is complex due to local geology and thus geochemical simulation was limited

Isotropic apparent diffusion coefficient mapping of postnatal cerebral development

Diffusion-weighted imaging (DWI) allows us to image the motion of tissue water. This has been used to demonstrate acute ischaemia. Diffusion imaging is also sensitive to water movement along neuronal tracts. Our objective was to map brain maturation in vivo using maps of apparent diffusion coefficient (ADC). We studied 22children without neurological disease aged between 2 and 720days. MRI was performed at 1.5tesla. Multislice single-shot echoplanar DWI was performed at b 0 and 1000s/mm2. ADC maps were generated automatically and measurements were performed in the basal ganglia, frontal and temporal white matter and the pons. There was a decrease over time in water diffusion in the areas examined, most marked in the frontal (0.887-1.898×10-3mm2/s) and temporal (1.077-1.748×10-3mm2/s)lobes. There was little change, after an initial decrease, in the basal ganglia (0.690-1.336×10-3mm2/s). There was a difference in water diffusion between the anterior (0.687-1.581×10-3mm2/s) and posterior (0.533-1.393×10-3mm2/s) pons. These changes correlate well with those observed in progressive myelination: the increased water content probably reflects incomplete myelination and the decrease with time in water motion reflects the increase in myelinated brai

Reasons to withhold intra-arterial thrombolysis in clinical practice

Background: In selected stroke centers intra-arterial thrombolysis (IAT) is used for the treatment of acute stroke patients presenting within 6hours of symptom onset. However, data about eligibility of acute stroke patients for IAT in clinical practice are very scarce. Methods: We collected prospectively data on indications advising for or against IAT of 230 consecutive stroke patients in a tertiary stroke center. Results: 76 patients (33.0%) presented within 3hours, 69 (30%) between 3 and 6hours of symptom onset and 85 (37%) later than 6hours. Arteriography was performed in 71 patients (31%) and IAT in 46 (20%). In 11 patients no or only peripheral branch occlusions were seen on arteriography and therefore IAT was not performed. In 9 patients the ICA was occluded and barred IAT and in five anatomical or technical difficulties made IAT impossible. 72 patients presenting within 6hours did not undergo arteriography and thrombolysis, mostly because of mild (n=44) or rapidly improving neurological deficits (n=13). Other reasons to withhold IAT were CT and/or clinical findings suggesting lacunar stroke due to small vessel occlusion (n=7), limiting comorbidty (n=7) and baseline international normalized ratio>1.7 (n=1). Conclusions: A third of the patients underwent diagnostic arteriography and one fifth received IAT. The most important reasons to withhold thrombolysis were presentation beyond the 6hours time window and mild or rapidly improving symptom

Multiresolution fuzzy clustering of functional MRI data

Recent developments in the analysis of functional MRI data reveal a shift from hypothesis-driven statistical tests to unsupervised strategies. One of the most promising approaches is the fuzzy clustering algorithm (FCA), whose potential to detect activation patterns has already been demonstrated. But the FCA suffers from three drawbacks: first the computational complexity, second the higher sensitivity to noise and third the dependence on the random initialization. With the multiresolution approach presented here, these weak points are significantly improved, as is demonstrated in our tests with simulated and real functional MRI dat

Water and nutrient fluxes as indicators for the sustainability of different land-use systems on the terra firme near Manaus - a project overview.

Comparision of the water and nutrient fluxes in different perennial land-se systems, either monocultures or mixed cropping systems, in order to determine the resource efficiency of perennial land-se systems. They were comparision of the monocultue systems with Theobroma grandiflorum (cupuacu) or Bactris gasipaes (pupunha), polyculture systems with cupuacu, pupunh, Bixa orellana (urucum) and Bertholletia excelsa (castanha-do-Para) and primary and secondary forest sites. In the first experimental year, the equipment was installed to measure raianfall, throughfall, stemflow and soil water fluxes. These data combined with measurements of nutrient concentrations inform about the element fluxes. for this purpose, laboratory facilities were implemented to analyze anions and cations in the different land-se systems. Additionally, the nutrient and organic matter content of the soils were studied. Firt results showed that the investigated tree species differ in their effect on the water distribution and nutrient accumulation within the different cropping systems

Degeneration of the cervical disc: histology compared with radiography and magnetic resonance imaging

Decisions about the treatment of neck pain are largely made on the basis of information gained from plain X-rays and magnetic resonance imaging (MRI), which are used routinely as part of preliminary investigation. We performed a descriptive cadaveric study to compare histology with radiography and MRI. We correlated plain radiography, disc height [Farfan index (FI)] and MRI findings with histology to assess the ability of radiology to detect significant pathologic lesions. The study included 52 motion segments from nine subjects over the age of 50, who underwent routine hospital autopsy. Disc degeneration was assessed by histology, radiography, disc height (FI: anterior disc height plus posterior disc height divided by anterioposterior diameter) and MRI using established grading systems. Most of the discs were classified radiologically as grade 1 (19/52), grade 2 (13/52), grade 3 (9/52) or grade 4 (3/52). Eight of the discs were graded as normal. The distribution of MRI grades was grade 0 (9/36), grade 1 (9/36), grade 2 (7/36), grade 3 (8/36) and grade 4 (3/36). Half of the discs (26/52) showed advanced (grade 4) degeneration histologically. FI correlated with histological grade (P=0.013), MRI grade (P=0.02) and radiological grade (P<0.001) of degeneration. Radiological and histological grade of degeneration showed a weak correlation (r=0.3, P=0.033). MRI correlated with overall histological grade (r=0.41, P=0.015, n=34). Histological features (e.g., tears, rim lesions, prolapse of nucleus material) were poorly recognised by MRI, which had a sensitivity for disc material prolapse and annulus tears of less than 40%. Our study showed that discs from patients over 50years are histologically severely degenerated; however, these changes may not be detected by conventional radiography and MR

Diffusion-weighted MRI in acute spinal cord ischaemia

Abstract : Acute spinal cord ischaemia is often undetectable with conventional MRI. Diffusion-weighted MRI (DWI) has been difficult to use in the spine because of susceptibility artefacts. We assessed the diagnostic value of echoplanar DWI for early confirmation of spinal cord ischaemia. We performed conventional MRI and DWI in two men and three women, aged 54-75years with clinically suspected acute spinal cord ischaemia. Imaging was performed 9-46h after the onset of symptoms, and 2-9days later to assess the extent of ischaemic signal change. Spatial resolution of DWI within the spine using standard equipment was poor, but in all patients, early DWI revealed areas of high signal indicating decreased diffusion, confirmed by measurement of apparent diffusion coefficients. Follow-up MRI showed high signal on T2-weighted images and contrast enhancement at the expected levels. Neurological deficits corresponded with radiological findings in four patients: various syndromes, including isolated bilateral weakness or sensory change and combined deficits, were found. Echoplanar DWI may be helpful for confirmation of spinal cord ischaemia in the acute stage, but follow-up T2-weighted images have superior spatial resolution and correlation with clinical findings and lesion exten

MetMap Enables Genome-Scale Methyltyping for Determining Methylation States in Populations

The ability to assay genome-scale methylation patterns using high-throughput sequencing makes it possible to carry out association studies to determine the relationship between epigenetic variation and phenotype. While bisulfite sequencing can determine a methylome at high resolution, cost inhibits its use in comparative and population studies. MethylSeq, based on sequencing of fragment ends produced by a methylation-sensitive restriction enzyme, is a method for methyltyping (survey of methylation states) and is a site-specific and cost-effective alternative to whole-genome bisulfite sequencing. Despite its advantages, the use of MethylSeq has been restricted by biases in MethylSeq data that complicate the determination of methyltypes. Here we introduce a statistical method, MetMap, that produces corrected site-specific methylation states from MethylSeq experiments and annotates unmethylated islands across the genome. MetMap integrates genome sequence information with experimental data, in a statistically sound and cohesive Bayesian Network. It infers the extent of methylation at individual CGs and across regions, and serves as a framework for comparative methylation analysis within and among species. We validated MetMap's inferences with direct bisulfite sequencing, showing that the methylation status of sites and islands is accurately inferred. We used MetMap to analyze MethylSeq data from four human neutrophil samples, identifying novel, highly unmethylated islands that are invisible to sequence-based annotation strategies. The combination of MethylSeq and MetMap is a powerful and cost-effective tool for determining genome-scale methyltypes suitable for comparative and association studies

Locally induced hypothermia for treatment of acute ischaemic stroke: a physical feasibility study

During the treatment of stroke by local intra-arterial thrombolysis (LIT) it is frequently possible to pass the blood clot with a micro-catheter, allowing perfusion of brain tissue distally to the occlusion. This possibility allows for new early treatments of ischaemic brain tissue, even before the blood clot has been removed. One potential new approach to preserve brain tissue at risk may be locally induced endovascular hypothermia. Physical parameters such as the required micro-catheter input pressure, output velocity and flow rates, and a heat exchange model, applicable in the case of a micro-catheter placed within a guiding catheter, are presented. Also, a simple cerebral temperature model is derived that models the temperature response of the brain to the perfusion with coolant fluids. Based on this model, an expression has been derived for the time needed to reach a certain cerebral target temperature. Experimental in vitro measurements are presented that confirm the usability of standard commercially available micro-catheters to induce local hypothermia of the brain. If applied in vivo, the model predicts a local cooling rate of ischaemic brain tissue of 300g of approximately 1°C in 1min, which is up to a factor 30-times faster than the time-consuming systemic hypothermia via the skin. Systemic body temperature is only minimally affected by application of local hypothermia, thus avoiding many limitations and complications known in systemic hypothermi