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PubMed1990

Meteorological modeling of arrival and deposition of fallout at intermediate distances downwind of the Nevada Test Site.

A three-dimensional atmospheric transport and diffusion model is used to calculate the arrival and deposition of fallout from 13 selected nuclear tests at the Nevada Test Site (NTS) in the 1950s. Results are used to extend NTS fallout patterns to intermediate downwind distances (300 to 1200 km). The radioactive cloud is represented in the model by a population of Lagrangian marker particles, with concentrations calculated on an Eulerian grid. Use of marker particles, with fall velocities dependent on particle size, provides a realistic simulation of fallout as the debris cloud travels downwind. The three-dimensional wind field is derived from observed data, adjusted for mass consistency. Terrain is represented in the grid, which extends up to 1200 km downwind of NTS and has 32-km horizontal resolution and 1-km vertical resolution. Ground deposition is calculated by a deposition-velocity approach. Source terms and relationships between deposition and exposure rate are based on work by Hicks. Uncertainty in particle size and vertical distributions within the debris cloud (and stem) allow for some model "tuning" to better match measured ground-deposition values. Particle trajectories representing different sizes and starting heights above ground zero are used to guide source specification. An hourly time history of the modeled fallout pattern as the debris cloud moves downwind provides estimates of fallout arrival times. Results for event HARRY illustrate the methodology. The composite deposition pattern for all 13 tests is characterized by two lobes extending out to the north-northeast and east-northeast, respectively, at intermediate distances from NTS. Arrival estimates, along with modeled deposition values, augment measured deposition data in the development of data bases at the county level; these data bases are used for estimating radiation exposure at intermediate distances downwind of NTS. Results from a study of event TRINITY are also presented.

Computer Simulation↗
PubMed2001

EMG-interference pattern analysis.

The EMG interference pattern, built up of single motor unit action potentials, may be analyzed subjectively, or objectively by computer aided, quantitative methods, like counting of zero-crossings, counting of spikes, amplitude measurements, integration of the area under the curve, decomposition techniques, power spectrum analysis and turn/amplitude analysis. Since the shape of the interference pattern of healthy muscles is dependent on age, sex, force, muscle, temperature, fatigue, fitness level, recording site and surrounding tissue, electrode type, sensitivity, filters, sampling frequency and threshold level, all methods of analyzing the IP have to be standardized. Quantitative methods of analyzing the EMG interference pattern may be used for monitoring botulinum toxin therapy of dystonia and spasticity, quantifying spontaneous activity, assessment of chronic muscle pain, neuro-urological and proctological function, and diagnosing neuromuscular disorders. For diagnostic purposes, the methods favored are those that use needle electrodes and do not require measurement or monitoring of muscle force. The most well-evaluated methods are those using turn/amplitude analysis, like the cloud methods and the peak-ratio analysis. Peak-ratio analysis has the advantage that reference limits are easy to obtain and that its utility is well established and confirmed by several investigations. Overall, automatic methods of EMG interference pattern analysis are powerful tools for diagnostic and non-diagnostic purposes.

Adult↗
PubMed1996

Enzyme flexibility, solvent and 'weak' interactions characterize thrombin-ligand interactions: implications for drug design.

BACKGROUND: The explosive growth in the rate of X-ray determination of protein structures is fuelled largely by the expectation that structural information will be useful for pharmacological and biotechnological applications. For example, there have been intensive efforts to develop orally administrable antithrombotic drugs using information about the crystal structures of blood coagulation factors, including thrombin. Most of the low molecular weight thrombin inhibitors studied so far are based on arginine and benzamidine. We sought to expand the database of information on thrombin-inhibitor binding by studying new classes of inhibitors. RESULTS: We report the structures of three new inhibitors complexed with thrombin, two based on 4-aminopyridine and one based on naphthamidine. We observe several geometry changes in the protein main chain and side chains which accompany inhibitor binding. The two inhibitors based on 4-aminopyridine bind in notably different ways: one forms a water-mediated hydrogen bond to the active site Ser195, the other induces a rotation of the Ser214-Trp215 peptide plane that is unprecedented in thrombin structures. These binding modes also differ in their 'weak' interactions, including CH-O hydrogen bonds and interactions between water molecules and aromatic pi-clouds. Induced-fit structural changes were also seen in the structure of the naphthamidine inhibitor complex. CONCLUSIONS: Protein flexibility and variable water structures are essential elements in protein-ligand interactions. Ligand design strategies that fail to take this into account may overlook or underestimate the potential of lead structures. Further, the significance of 'weak' interactions must be considered both in crystallographic refinement and in analysis of binding mechanisms.

4-Aminopyridine↗
PubMed2002

Virtual reality exposure therapy for World Trade Center Post-traumatic Stress Disorder: a case report.

Done properly by experienced therapists, re-exposure to memories of traumatic events via imaginal exposure therapy can lead to a reduction of Post-traumatic Stress Disorder (PTSD) symptoms. Exposure helps the patient process and habituate to memories and strong emotions associated with the traumatic event: memories and emotions they have been carefully avoiding. But many patients are unwilling or unable to self-generate and re-experience painful emotional images. The present case study describes the treatment of a survivor of the World Trade Center (WTC) attack of 9-11-01 who had developed acute PTSD. After she failed to improve with traditional imaginal exposure therapy, we sought to increase emotional engagement and treatment success using virtual reality (VR) exposure therapy. Over the course of six 1-h VR exposure therapy sessions, we gradually and systematically exposed the PTSD patient to virtual planes flying over the World Trade Center, jets crashing into the World Trade Center with animated explosions and sound effects, virtual people jumping to their deaths from the burning buildings, towers collapsing, and dust clouds. VR graded exposure therapy was successful for reducing acute PTSD symptoms. Depression and PTSD symptoms as measured by the Beck Depression Inventory and the Clinician Administered PTSD Scale indicated a large (83%) reduction in depression, and large (90%) reduction in PTSD symptoms after completing VR exposure therapy. Although case reports are scientifically inconclusive by nature, these strong preliminary results suggest that VR exposure therapy is a promising new medium for treating acute PTSD. This study may be examined in more detail at www.vrpain.com.

Adult↗
PubMed1988

[Intraarterial urokinase infusion therapy for the acute intracranial major artery occlusion].

Recently percutaneous transluminal coronary recanalization therapy (PTCR) with urokinase infusion has became one of popular technique for coronary arterial occlusion. This paper reported clinical experience of intraarterial urokinase infusion therapy for acute or superacute stroke patients. The procedure was followed by angiographical study which revealed the major intracerebral arterial occlusion in three cases. Case 1: A 74-year-old female had sudden onset of clouding of consciousness with complete left hemiplegia. The patient was in our urological ward because of treatment for her right ureter tumor, as the patient was immediately subjected to angiographical study and complete occlusion of the trunk of the right middle cerebral artery was revealed four hours after onset. Successively 240,000 IU of urokinase solution was injected through the arterial catheter after angiographical study. This procedure repeated two times with 10 minute intervals. So total amount of 720,000 IU of urokinase was given by intraarterial injection. Immediately after the last urokinase injection the patient started to recover her consciousness and weakness. Simultaneous angiogram demonstrated partial recanalization of the proximal branches of the middle cerebral artery. The following day, she had complete recovery from her neurological deficits although she had transient hemorrhagic tendency. The final angiogram showed no existence of obstructed cerebral arteries as well as no low density areas in computed tomographic images. Case 2: A 73-year-old female, with the left internal carotid occlusion at the site of C1-2 portion, was instituted infusion therapy of similar procedure with total amount of 960,000 IU oi urokinase ten to twenty hours after onset. However, no rewarding was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2002

Fitting manifold surfaces to three-dimensional point clouds.

We present a technique for fitting a smooth, locally parameterized surface model (called the manifold surface model) to unevenly scattered data describing an anatomical structure. These data are acquired from medical imaging modalities such as CT scans or MRI. The manifold surface is useful for problems which require analyzable or parametric surfaces fitted to data acquired from surfaces of arbitrary topology (e.g., entire bones). This surface modeling work is part of a larger project to model and analyze skeletal joints, in particular the complex of small bones within the wrist and hand. To demonstrate the suitability of this model we fit to several different bones in the hand, and to the same bone from multiple people.

Carpal Bones↗
PubMed2006

Revisiting the potential of time-domain indexes in short-term HRV analysis.

In the context of HRV analysis, we evaluated the information content of two measures that can easily be derived from the classical RR time-domain indexes. The two measures are: 1) the ratio sd/rmssd, where sd is the RR standard deviation and rmssd is the root mean square of squared differences of consecutive RR beats; and 2) the ratio sd2/sd1, where sd2 and sd1 are extracted from the Poincaré plot and represent the transversal and longitudinal dispersion of the cloud of points (RR(i),RR(i)(+1)). We compared the performance of the two measures with that of the classical LF/HF ratio in a group of healthy subjects who underwent a 70 degrees upright tilt test. The goodness of the results obtained by the two measures, the simplicity of their calculation and their applicability free from a priori assumptions on the characteristics of the data are proposed to the attention of the community involved in the HRV analysis as a possible alternative to the LF/HF ratio.

Adult↗
PubMedDate not supplied

Holographic electron density shape theorem and its role in drug design and toxicological risk assessment.

Each complete, boundaryless molecular electron density is fully determined by any nonzero volume piece of the electron density cloud. This inherent feature of molecules, called the "holographic" property of molecular electron densities, provides a strong foundation for the local, quantum chemical shape analysis of various functional groups, pharmacophores, and other local molecular moieties. A proof is presented for the relevant molecular shape theorem, the "holographic electron density shape theorem", and the role of this theorem in quantum chemical, quantitative shape-activity relations (QShAR) is discussed. The quantum chemical methods of molecular shape analysis can be extended to ab initio quality electron densities of macromolecules, such as proteins, as well as to local molecular moieties, such as functional groups or pharmacophores, based on the transferability and additivity of local, fuzzy density fragments and the associated local density matrixes within the framework of the ADMA (Adjustable Density Matrix Assembler) approach. In addition to new results on chemical bonding and the development of macromolecular force methods, the new methodologies are also applicable to QShAR studies in computer-aided drug discovery and in toxicological risk assessment.

Drug Design↗
PubMed1991

Single cell imaging reveals abnormal intracellular calcium signals within rheumatoid synovial neutrophils.

Intracellular calcium (Ca2+) signalling in synovial fluid (SF) polymorphonuclear leucocytes (PMN) from patients with rheumatoid arthritis (RA) was compared to RA and normal circulating blood PMN using single cell imaging. RA SF PMN stimulated by the peptide f-Met-Leu-Phe (FMLP) showed a striking difference in the release of Ca2+ from the intracellular store compared to RA and normal circulating blood PMN. Stimulation caused the release of a very dispersed, nonrestricted 'cloud' of Ca2+ in 60% of RA SF PMN compared to the highly localized and restricted 'cloud' observed in only 30% of normal circulating PMN. In the presence of extracellular Ca2+, both RA SF and normal blood PMN showed heterogeneity in both the timing and magnitude of their cytosolic free Ca2+ signalling. These observations imply that the Ca2+ signalling mechanism in RA SF and RA blood PMN has been primed in a way which could exacerbate the release of inflammatory mediators. This may have serious implications for explaining the aberrant behaviour of SF PMN in RA.

Adult↗
PubMed2005

Automated 3-D reconstruction of the surface of live early-stage amphibian embryos.

Although three-dimensional (3-D) reconstructions of the surfaces of live embyos are vital to understanding embryo development, morphogenetic tissue movements and other factors have prevented the automation of this task. Here, we report an integrated set of software algorithms that overcome these challenges, making it possible to completely automate the reconstruction of embryo surfaces and other textured surfaces from multiview images. The process involves: 1) building accurate point correspondences using a robust deformable template block matching algorithm; 2) removing outliers using fundamental matrix calculations in conjunction with a RANSAC algorithm; 3) generating 3-D point clouds using a bundle adjustment algorithm that includes camera position and distortion corrections; 4) meshing the point clouds into triangulated surfaces using a Tight Cocone algorithm that produces water tight models; 5) refining surfaces using midpoint insertion and Laplacian smoothing algorithms; and 6) repeating these steps until a measure of convergence G, the rms difference between successive reconstructions, is below a specified threshold. Reconstructions were made of 2.2-mm diameter, neurulation-stage axolotl (amphibian) embryos using 44 multiview images collected with a robotic microscope. A typical final model (sixth iteration) contained 3787 points and 7562 triangles and had an error measure of G = 5.9 microm.

Algorithms↗
PubMed2006

Selective intercalation of Cs+ in the "V"-shaped cavity of a bichromophoric anion radical: Cs+ assisted pi-s-pi-delocalization of an electron.

EPR studies in tetrahydrofuran, reveal that the one electron reduction of 1-(9-methyl-9H-fluoren-9-yl)-4-methylbenzene via electron transfer from cesium metal produces an anion radical that has a large affinity for the cesium cation. The affinity of this anion radical for Cs+ is so great that it will actually "suck" the Cs+ (but not Na+ or K+) right out of the grasp of 18-crown-6, leading to a cation-assisted pi-stacked complex, where the s-orbital of the metal cation is simultaneously overlapped with the pi-clouds of the phenyl and fluorenyl moieties. At ambient temperature, proton- and cesium-electron coupling constants are rapidly (on the EPR time scale) modulated as a result of the simultaneous existence of two interconverting conformers having an averaged cesium splitting (a(Cs)) of about 1.6 G. The pi-s-pi-electronic coupling can be turned on or off via the addition or removal of cesium cations. Analogous pi-s-pi-electronic coupling is observed in the 1,4-bis(9-methyl-9H-fluoren-9-yl)benzene-cesium system.

Anions↗
PubMed1984

[Obstructive hydrocephalus in cerebellar infarcts].

Large cerebellar ischaemic infarction may act as a space-occupying lesion and cause acute ventricular dilatation secondary to brain stem compression. 8 cases are regarded and the clinical course and therapy are discussed. After acute onset with vestibular and cerebellar symptoms, signs of progressive clouding of consciousness, accompanied often by signs of brain stem compression develop leading finally to decerebration syndrome. CT reveals an extensive hypodense area, usually in the lower part of the cerebellar hemisphere, compression and shift of the IVth ventricle and dilatation of 3rd and lateral ventricles. Drainage of ventricular fluid alone is not sufficient and the therapy of choice is the resection of infarcted tissue. Even in patients, who were operated in the early phase of decerebration excellent recovery was noted.

Adult↗
PubMed1996

Why HOC+ is detectable in interstellar clouds: the rate of the reaction between HOC+ and H2

The recent confirmation by Ziurys and Apponi of the detection of HOC+ toward Sgr B2 (OH), and their identification of the ion in Orion-KL and several other sources show that HOC+ is far more abundant than predicted by previous ion-molecule models. In these models, the reaction HOC(+) + H2 --> HCO(+) + H2 is assumed to rapidly destroy HOC+, based on the results of a prior calculation. We have recalculated the rate of this reaction as a function of temperature using a new ab initio potential surface and a phase space approach to the dynamics which includes tunneling. The newly calculated rate is small (< or = 1 x 10(-10) cm3 s-1) at temperatures under 100 K.

Algorithms↗
PubMed2001

Time-to-passage judgments on circular trajectories are based on relative optical acceleration.

Current theories of arrival time have difficulty explaining performance in the common but neglected case of nonlinear approach. Global tau, a variable supposed to guide time-to-passage (TTP) judgments of objects approaching on linear trajectories, does not apply to circular movement. However, TTP judgments are surprisingly accurate in such cases. We simulated movement through a three-dimensional cloud of point-lights on various circular trajectories. Arrival-time judgments were found to be above chance when observers had to determine which of two expansionless targets would pass them first. Similar to the inside bias observed in heading studies on circular trajectories, observers showed a strong bias to select the target on the inside of their own curved motion path as passing by first. Analysis of the projected target motion revealed that targets on the inside had lower optical velocities and relatively high optical acceleration rates. Empirical TTP judgments agreed best with a strategy based on relative optical velocity changes.

Adult↗
PubMed1989

El Chichon volcanic aerosols: impact of radiative, thermal, and chemical perturbations.

We examine the consequences of the eruption of the El Chichon volcano on the Earth's stratospheric chemistry. Formed after the eruption, the volcanic aerosol cloud, with a peak particle density at 27 km, was very efficient at altering the radiation field. The results of a one-dimensional radiative transfer model show that the total radiation increased by 8% within the aerosol layer longward of 3000 angstroms. At certain altitudes and wavelengths below 3000 angstroms, the total radiation decreased by 15%. Consequently, there are changes in the photolysis rates obtained with a one-dimensional photochemical model: for example, O2 photodissociation rate constants decrease by 10%, while O3 photodissociation rate constants increase by a comparable amount. A combination of this radiation change and the effect of a temperature variation of a few degrees causes the abundance of O3 to decrease by 7% at 24 km, in good agreement with the Solar Backscattered Ultraviolet experiment (SBUV) measurements of a 5-10% decrease. The combined radiative and thermal perturbations on the concentrations of O, O(1 D), OH, HO2, H2O2, NO, NO2, NO3, N2O5, HNO3, HO2NO2, Cl, ClO, ClO2, HOCl, ClNO3, and HCl are computed and presented in detail. However, these changes as calculated are insufficient to explain the observations of significant decreases in NO and NO2 and increases in HCl. A heterogeneous reaction catalyzed by aerosol surfaces which transforms ClNO3 into HCl provides a pathway for sequestering NOx, and at the same time reduces ClNO3 in favor of HCL. The inclusion of this reaction in the model leads to a satisfactory single-step explanation of the otherwise puzzling observations of NO, NO2, and HCl. The observed lack of change in HNO3 cannot be explained by this hypothesis. The effects of a number of heterogeneous reactions, some believed to be important for the Antarctic stratosphere, have been assessed with our model. We also examine the hypothesis of direct injection of gases from the volcano into the stratosphere. Only an unrealistically large injection (60% column increase above 12 km) results in an HCl increase in agreement with observations. An equally large water injection decreases HCl, and decreases the NO and NO2 by as much as 20%, but still does not simulate the observed NOx decrease.

Aerosols↗
PubMed2004

Development of a new three-dimensional cranial imaging system.

The development of a new three-dimensional (3D) imaging system designed to obtain a digital image of an infant's cranium is described. This system is intended to replace the manual plaster-casting technique currently used during the process of fabricating cranial remodeling bands. The system uses 18 triangulated digital cameras and the projection of random infrared patterns to capture a 360 degrees image of an infant's cranium instantaneously, including the face and top of the head. Accuracy was calculated by comparing models digitized with this system with the same models digitized with high-precision inspection equipment. Safety was documented under guidelines established by the American Council of Governmental Industrial Hygienists. Images were acquired in 0.008 seconds and processed for viewing in software within 2.5 minutes. Accuracy was calculated to be +/-0.236 mm. Hazard analysis confirmed the system to be safe for direct continuous exposure. The data acquired may be viewed as a point cloud, wire frame, or surface on which a digital photograph (ie, texture) is automatically overlaid. Physical models are created by exporting the digital data to a multiaxis milling machine or stereolithography machine. Quantitative data (linear and surface measurements, curvature, and volumes) can be obtained directly from the digital data. The cranial imaging system is a safe and accurate method of obtaining digital 3D images of an infant's cranium. Along with the obvious clinical and manufacturing benefits, it also has significant potential as a research tool for documenting the natural history and evaluating the treatment of plagiocephaly.

Cephalometry↗
PubMed2006

Retrospective dose assessment for the population living in areas of local fallout from the Semipalatinsk Nuclear Test Site Part II: Internal exposure to thyroid.

A methodology to assess internal exposure to thyroid from radioiodines for the residents living in settlements located in the vicinity of the Semipalatinsk Nuclear Test Site is described that is the result of many years of research, primarily at the Moscow Institute of Biophysics. This methodology introduces two important concepts. First, the biologically active fraction, is defined as the fraction of the total activity on fallout particles with diameter less than 50 microns. That fraction is retained by vegetation and will ultimately result in contamination of dairy products. Second, the relative distance is derived as a dimensionless quantity from information on test yield, maximum height of cloud, and average wind velocity and describes how the biologically active fraction is distributed with distance from the site of the explosion. The parameter is derived in such a way that at locations with equal values of relative distance, the biologically active fraction will be the same for any test. The estimates of internal exposure to thyroid for the residents of Dolon and Kanonerka villages, for which the external exposure were assessed and given in a companion paper (Gordeev et al. 2006) in this conference, are presented. The main sources of uncertainty in the estimates are identified.

Body Burden↗
PubMedDate not supplied

Haptics-based dynamic implicit solid modeling.

This paper systematically presents a novel, interactive solid modeling framework, Haptics-based Dynamic Implicit Solid Modeling, which is founded upon volumetric implicit functions and powerful physics-based modeling. In particular, we augment our modeling framework with a haptic mechanism in order to take advantage of additional realism associated with a 3D haptic interface. Our dynamic implicit solids are semi-algebraic sets of volumetric implicit functions and are governed by the principles of dynamics, hence responding to sculpting forces in a natural and predictable manner. In order to directly manipulate existing volumetric data sets as well as point clouds, we develop a hierarchical fitting algorithm to reconstruct and represent discrete data sets using our continuous implicit functions, which permit users to further design and edit those existing 3D models in real-time using a large variety of haptic and geometric toolkits, and visualize their interactive deformation at arbitrary resolution. The additional geometric and physical constraints afford more sophisticated control of the dynamic implicit solids. The versatility of our dynamic implicit modeling enables the user to easily modify both the geometry and the topology of modeled objects, while the inherent physical properties can offer an intuitive haptic interface for direct manipulation with force feedback.

Algorithms↗