Estimating traveltimes and groundwater flow patterns using 3D time-lapse crosshole ERT imaging of electrical resistivity fluctuations induced by infiltrating river water

The infiltration of river water into aquifers is of high relevance to drinking-water production and is a key driver of biogeochemical processes in the hyporheic and riparian zone, but the distribution and quantification of the infiltrating water are difficult to determine using conventional hydrological methods (e.g., borehole logging and tracer tests). By time-lapse inverting crosshole ERT (electrical resistivity tomography) monitoring data, we imaged groundwater flow patterns driven by river water infiltrating a perialpine gravel aquifer in northeastern Switzerland. This was possible because the electrical resistivity of the infiltrating water changed during rainfall-runoff events. Our time-lapse resistivity models indicated rather complex flow patterns as a result of spatially heterogeneous bank filtration and aquifer heterogeneity. The upper part of the aquifer was most affected by the river infiltrate, and the highest groundwater velocities and possible preferential flow occurred at shallow to intermediate depths. Time series of the reconstructed resistivity models matched groundwater electrical resistivity data recorded on borehole loggers in the upper and middle parts of the aquifer, whereas the resistivity models displayed smaller variations and delayed responses with respect to the logging data. in the lower part. This study demonstrated that crosshole ERT monitoring of natural electrical resistivity variations of river infiltrate could be used to image and quantify 3D bank filtration and aquifer dynamics at a high spatial resolution.

Thrombin-sensitive photodynamic agents: a novel strategy for selective synovectomy in rheumatoid arthritis.

Protease-sensitive macromolecular prodrugs have attracted interest for bio-responsive drug delivery to sites with up-regulated proteolytic activities such as inflammatory or cancerous lesions. Here we report the development of a novel polymeric photosensitizer prodrug (T-PS) to target thrombin, a protease up-regulated in synovial tissues of rheumatoid arthritis (RA) patients, for minimally invasive photodynamic synovectomy. In T-PS, multiple photosensitizer units are tethered to a polymeric backbone via short, thrombin-cleavable peptide linkers. Photoactivity of the prodrug is efficiently impaired due to energy transfer between neighbouring photosensitizer units. T-PS activation by exogenous and endogenous thrombin induced an increase in fluorescence emission by a factor of 16 after in vitro digestion and a selective fluorescence enhancement in arthritic lesions in vivo, in a collagen-induced arthritis mouse model. In vitro studies on primary human synoviocytes showed a phototoxic effect only after enzymatic digestion of the prodrug and light irradiation, thus demonstrating the functionality of T-PS induced PDT. The developed photosensitizer prodrugs combine the passive targeting capacity of macromolecular drug delivery systems with site-selective photosensitizer release and activation. They illuminate lesions with pathologically enhanced proteolytic activity and induce cell death, subsequent to irradiation.

Forensic imaging: New challenges for radiographers : B-588

Purpose: Cross-sectional imaging techniques have pioneered forensic medicine. The involvement of a radiographer and formation of "forensic radiographers" allows an improvement of the quality of radiological examinations and facilitates the implementation of techniques, such as sample collections, and the performance of post-mortem angiography. Methods and Materials: During a period of three months, five radiographers with clinical experience have undergone a special training in order to learn procedures dedicated to forensic imaging. These procedures involved: I). acquisition of MDCT data, II). sample collection for toxicological or histological analyses by performing CT-guided biopsies and liquid sampling, III). post-mortem angiography and IV). post-processing of all data acquired. To perform the post-mortem angiography, radiographers were in charge of the preparation of the perfusion device and the investigated body. Therefore, cannulas were inserted into the femoral vessels and connected to the machine. For angiography, the radiographers had to synchronize the perfusion with the CT-acquisitions. Results: All five radiographers have acquired new skills to become "forensic radiographers". They were able to perform post-mortem MDCT, sample collection, post-mortem angiography and post-processing of the acquired data all by themselves. Most problems have been observed concerning the preparation of the body for post-mortem angiography. Conclusion: Our experience shows that radiographers are able to perform high quality examinations after a short period of training. Their collaboration is well accepted by the forensic team and regarding the increase of radiological exams in forensic department, it would be nonsense to exclude radiographers from the forensic-radiological team.

Selective ablation of photovoltaic materials with UV laser sources for monolithic interconnection of devices based on a-Si:H

Lasers are essential tools for cell isolation and monolithic interconnection in thin-film-silicon photovoltaic technologies. Laser ablation of transparent conductive oxides (TCOs), amorphous silicon structures and back contact removal are standard processes in industry for monolithic device interconnection. However, material ablation with minimum debris and small heat affected zone is one of the main difficulty is to achieve, to reduce costs and to improve device efficiency. In this paper we present recent results in laser ablation of photovoltaic materials using excimer and UV wavelengths of diode-pumped solid-state (DPSS) laser sources. We discuss results concerning UV ablation of different TCO and thin-film silicon (a-Si:H and nc-Si:H), focussing our study on ablation threshold measurements and process-quality assessment using advanced optical microscopy techniques. In that way we show the advantages of using UV wavelengths for minimizing the characteristic material thermal affection of laser irradiation in the ns regime at higher wavelengths. Additionally we include preliminary results of selective ablation of film on film structures irradiating from the film side (direct writing configuration) including the problem of selective ablation of ZnO films on a-Si:H layers. In that way we demonstrate the potential use of UV wavelengths of fully commercial laser sources as an alternative to standard backscribing process in device fabrication.

Vascular Integrins: Therapeutic and Imaging Targets of Tumor Angiogenesis

Cells, including endothelial cells, continuously sense their surrounding environment and rapidly adapt to changes in order to assure tissues and organs homeostasis. The extracellular matrix (ECM) provides a physical scaffold for cell positioning and represents an instructive interface allowing cells to communicate over short distances. Cell surface receptors of the integrin family emerged through evolution as essential mediators and integrators of ECM-dependent communication. In preclinical studies, pharmacological inhibition of vascular integrins suppressed angiogenesis and inhibited tumor progression. alpha(V)beta(3) and alpha(V)beta(5) were the first integrins targeted to suppress tumor angiogenesis. Subsequently, additional integrins, in particular alpha(1)beta(1), alpha(2)beta(1), alpha(5)beta(1), and alpha(6)beta(4), emerged as potential therapeutic targets. Integrin inhibitors are currently tested in clinical trials for their safety and antiangiogenic/antitumor activity. In this chapter, we review the role of integrins in angiogenesis and present recent advances in the use of integrin antagonists as potential therapeutics in cancer and discuss future perspectives.

Pancréatite aiguë clinique après chimio-embolisation sélective d'un carcinome hépatocellulaire [Acute clinical pancreatitis following selective transcatheter arterial chemoembolization of hepatocellular carcinoma]

Acute pancreatitis can complicate non-selective transcatheter arterial embolization of hepatocellular carcinoma with an incidence ranging from 1,7% (acute clinical pancreatitis) to 40% (biological pancreatitis). This complication is thought to be related to embolization of extrahepatic arterial collaterals.We report herein a case of acute clinical pancreatitis developing within 24 hours after a second course of selective transcatheter arterial chemo-embolization into the proper hepatic artery. Neither anatomical arterial variation nor particular risk factor for acute pancreatitis could be identified. This complication is unusual after selective arterial embolization. Because it may clinically mimick a postembolization syndrome, dosage of serum pancreatic enzymes should be performed systematically in case of abdominal pain following chemoembolization.

Collective bargaining in U.S. higher education, 1960-1971 : a selective bibliography, 1972.

This document represents a substantial attempt to survey the literature of labor negotiations as it relates to the faculty in higher education.

PPAR disruption: Cellular mechanisms and physiological consequences

Endocrine disruption is defined as the perturbation of the endocrine system, which includes disruption of nuclear hormone receptor signalling. Peroxisome proliferator-activated receptors (PPARs) represent a family of nuclear receptors that has not yet been carefully studied with regards to endocrine disruption, despite the fact that PPARs are known to be important targets for xenobiotics. Here we report a first comprehensive approach aimed at defining the mechanistic basis of PPAR disruption focusing on one chemical, the plasticizer monethylhexyl phthalate (MEHP), but using a variety of methodologies and models. We used mammalian cells and a combination of biochemical and live cell imaging techniques to show that MEHP binds to PPAR gamma and selectively regulates interactions with coregulators. Micro-array experiments further showed that this selectivity is translated at the physiological level during adipocyte differentiation. In that context, MEHP functions as a selective PPAR modulator regulating only a subset of PPAR gamma target genes compared to the action of a full agonist. We also explored the action of MEHP on PPARs in an aquatic species, Xenopus laevis, as many xenobiotics are found in aquatic ecosystems. In adult males, micro-array data indicated that MEHP influences liver physiology, possibly through a cross-talk between PPARs and estrogen receptors (ER). In early Xenopus laevis embryos, we showed that PPAR beta/delta exogenous activation by an agonist or by MEHP affects development. Taken together our results widen the concept of endocrine disruption by pinpointing PPARs as key factors in that process.

Post-mortem cardiac 3-T magnetic resonance imaging: visualization of sudden cardiac death?

OBJECTIVES: This study aimed to investigate post-mortem magnetic resonance imaging (pmMRI) for the assessment of myocardial infarction and hypointensities on post-mortem T2-weighted images as a possible method for visualizing the myocardial origin of arrhythmic sudden cardiac death. BACKGROUND: Sudden cardiac death has challenged clinical and forensic pathologists for decades because verification on post-mortem autopsy is not possible. pmMRI as an autopsy-supporting examination technique has been shown to visualize different stages of myocardial infarction. METHODS: In 136 human forensic corpses, a post-mortem cardiac MR examination was carried out prior to forensic autopsy. Short-axis and horizontal long-axis images were acquired in situ on a 3-T system. RESULTS: In 76 cases, myocardial findings could be documented and correlated to the autopsy findings. Within these 76 study cases, a total of 124 myocardial lesions were detected on pmMRI (chronic: 25; subacute: 16; acute: 30; and peracute: 53). Chronic, subacute, and acute infarction cases correlated excellently to the myocardial findings on autopsy. Peracute infarctions (age range: minutes to approximately 1 h) were not visible on macroscopic autopsy or histological examination. Peracute infarction areas detected on pmMRI could be verified in targeted histological investigations in 62.3% of cases and could be related to a matching coronary finding in 84.9%. A total of 15.1% of peracute lesions on pmMRI lacked a matching coronary finding but presented with severe myocardial hypertrophy or cocaine intoxication facilitating a cardiac death without verifiable coronary stenosis. CONCLUSIONS: 3-T pmMRI visualizes chronic, subacute, and acute myocardial infarction in situ. In peracute infarction as a possible cause of sudden cardiac death, it demonstrates affected myocardial areas not visible on autopsy. pmMRI should be considered as a feasible post-mortem investigation technique for the deceased patient if no consent for a clinical autopsy is obtained.

Crossed ataxia: a case report and a diffusion tensor imaging tractography study.

Background and Purpose-Ever since the seminal description of ataxic hemiparesis contralateral to a pontine lesion by Miller-Fisher, the question of why contralesional crossing pontocerebellar fibers do not more frequently produce ipsilesional hemiataxia was raised. The few cases of "quadrataxic hemiparesis" or bilateral leg ataxia remain exceptions.Summary of Case-We report an even more unusual variant, namely "crossed ataxia" of the contralesional arm and the ipsilesional leg subsequent to an anteromedial pontine ischemic stroke.Conclusions-MRI diffusion tensor imaging tractography shows that caudal contralesional crossing pontocerebellar fibers (those for the leg) travel trough the lesion, whereas more rostral fibers (those for the arm) are spared. (Stroke. 2011; 42:e571-e573.)

Automatic quality assessment in structural brain magnetic resonance imaging

MRI has evolved into an important diagnostic technique in medical imaging. However, reliability of the derived diagnosis can be degraded by artifacts, which challenge both radiologists and automatic computer-aided diagnosis. This work proposes a fully-automatic method for measuring image quality of three-dimensional (3D) structural MRI. Quality measures are derived by analyzing the air background of magnitude images and are capable of detecting image degradation from several sources, including bulk motion, residual magnetization from incomplete spoiling, blurring, and ghosting. The method has been validated on 749 3D T(1)-weighted 1.5T and 3T head scans acquired at 36 Alzheimer's Disease Neuroimaging Initiative (ADNI) study sites operating with various software and hardware combinations. Results are compared against qualitative grades assigned by the ADNI quality control center (taken as the reference standard). The derived quality indices are independent of the MRI system used and agree with the reference standard quality ratings with high sensitivity and specificity (>85%). The proposed procedures for quality assessment could be of great value for both research and routine clinical imaging. It could greatly improve workflow through its ability to rule out the need for a repeat scan while the patient is still in the magnet bore.

Navigator-gated and real-time motion corrected free-breathing MR Imaging of myocardial late enhancement.

PURPOSE: A new magnetic resonance imaging approach for detection of myocardial late enhancement during free-breathing was developed. METHODS AND RESULTS: For suppression of respiratory motion artifacts, a prospective navigator technology including real-time motion correction and a local navigator restore was implemented. Subject specific inversion times were defined from images with incrementally increased inversion times acquired during a single dynamic scout navigator-gated and real-time motion corrected free-breathing scan. Subsequently, MR-imaging of myocardial late enhancement was performed with navigator-gated and real-time motion corrected adjacent short axis and long axis (two, three and four chamber) views. This alternative approach was investigated in 7 patients with history of myocardial infarction 12 min after i. v. administration of 0.2 mmol/kg body weight gadolinium-DTPA. CONCLUSION: With the presented navigator-gated and real-time motion corrected sequence for MR-imaging of myocardial late enhancement data can be completely acquired during free-breathing. Time constraints of a breath-hold technique are abolished and optimized patient specific inversion time is ensured.