Blood pool contrast-enhanced MRA: improved arterial visualization in the steady state

Blood pool agents (BPAs) for contrast-enhanced magnetic resonance angiography (CE-MRA) allow prolonged imaging during the steady state when the agent is distributed through the complete vascular system. This increases both the spatial resolution and the contrast resolution. However, simultaneous venous and arterial enhancement hampers interpretation. For the pelvic region of the vasculature, it is shown that arterial visualization in this equilibrium phase can be improved if the central arterial axis (CAA) is known. However, manually obtaining this axis is not feasible in clinical practice. Therefore, a method is presented that utilizes images acquired during the first pass of the contrast agent to find the CAA in the steady-state data with minimum user initialization. The accuracy of the resulting CAA is compared with tracings of three observers in six patient datasets. It was found that the mean difference between the semiautomatic method and the manual delineation is 1.32 mm in the steady-state data, and that the resulting CAA was always within the arterial lumen, which is an important prerequisite for both improved visualization and segmentation.     

Growth of Carnobacterium divergens V41 and production of biogenic amines and divercin V41 in sterile cold-smoked salmon extract at varying temperatures, NaCl levels, and glucose concentrations

A complete factorial design 2(3) was used to study some aspects of Carnobacterium divergens V41 metabolism (growth, biogenic amine production, and divercin V41 production) in sterile cold-smoked salmon extract (SSE) at varying temperatures (3 to 9 degrees C), NaCl levels (2.5 to 6.5%), and glucose concentrations (2 to 6 g liter(-1)). The results showed that temperature and NaCl content were the most influential factors on growth parameters in SSE. Predictive models are suggested for the assessment of C. divergens lag time (t(lag)) and maximum specific growth rate (micro(max)) Among the biogenic amines studied, only tyramine was found to be produced by C. divergens in SSE. Furthermore, we showed that temperature, NaCl, and glucose variations did not greatly affect tyramine and divercin V41 production by the bacteria under the experimental conditions used. Indeed, divercin V41, a bacteriocin from C. divergens V41 that is highly active against some Listeria strains, was produced in SSE even under harsh culture conditions. Similarly, tyramine production in SSE was delayed at 3 degrees C but reached 35 microg ml(-1) in all experiments after 27 days of storage. However, this final tyramine concentration in SSE is low compared with the threshold values of 100 to 800 microg g(-1) reported as the potentially toxic dose in foods. Thus, we have found that C. divergens V41 is a promising strain for the biopreservation of refrigerated cold-smoked salmon.     

Factors associated with body temperature of healthy Holstein dairy cows during the first 10 days in milk

In this prospective observational study rectal and vaginal temperature of 82 (26 primiparous, 56 multiparous) early post-partum healthy dairy cows that calved without intervention within 3 months and did not show clinical signs of infectious and metabolic diseases were continuously measured and evaluated for associations with plausible factors during the first 10 days in milk (DIM). During May, June and July mean (±SD) temperature humidity index (THI) was 60·1±5; 66·8±5·6 and 74·2±4·3, respectively. Environmental conditions had a negligible effect on body temperature (BT) during May (P<0·05). During June and July, however, the ambient temperature and THI influenced BT (P<0·05). Furthermore, plausible factors like parity, DIM, months and time of day had an effect on BT (P<0·05). Overall, primiparous cows demonstrated 0·2°C greater BT during the first 10 DIM than multiparous cows. The effect of parity, however, on BT varied between DIM according to month (P<0·001). During this 3-month study period all cows demonstrated BT rhythms; however, the amplitude of BT increased from May to July (0·3 to 0·7°C). A greater proportion of the vaginal temperature measurements exceeded a threshold tested (≥39·5°C) during July (46·8%) than in June (33·9%) and May (19·3%). Overall the percentage of BT values above a threshold of ≥39·5°C was lower during the period 6.00-10.00 compared with the remaining 20 h (P<0·05). Therefore this study concluded that the BT of healthy post-partum dairy cows during the period 1-10 DIM post partum is greater compared with the reference range of 38·6 to 39·5°C reported by others and is influenced by parity, DIM, time of day and THI. When the association between BT and THI increased the reliability of threshold levels of BT (≥39·5°C) decreased.     

Waiting-time approximations for cyclic-service systems with switchover times

Mean waiting-time approximations are derived for a single-server multi-queue system with nonexhaustive cyclic service. Nonzero switchover times of the server between consecutive queues are assumed. The main tool used in the derivation is a pseudo-conservation law recently found by Watson (1984). The approximation is simpler and, as extensive simulations show, more accurate than existing approximations. Moreover, it gives very good insight into the qualitative behaviour of cyclic-service queueing systems.     

Types and Timing of Inter–organizational Communication in New Product Development

Managing the communication between the participants involved in inter–organizational product development is complex. The traditional models of new product development are not sufficient to gain insight in effective management practices in this respect. Our study explored the inter–organizational communication in a research and development project. Our results confirm Gersick’s model that looks upon new product development as being punctuated by periods of rapid change. In these periods, including the start–up, explorative prototype stage, and completion of the project, inter–organizational communication is essential about design objectives and project planning, contextual factors and the required resources, skills and knowledge.     

Electronic Structure of Colloidal 2H-MoS2 Mono and Bilayers Determined by Spectroelectrochemistry

The electronic structure of mono and bilayers of colloidal 2H-MoS₂ nanosheets synthesized by wet-chemistry using potential-modulated absorption spectroscopy (EMAS), differential pulse voltammetry, and electrochemical gating measurements is investigated. The energetic positions of the conduction and valence band edges of the direct and indirect bandgap are reported and observe strong bandgap renormalization effects, charge screening of the exciton, as well as intrinsic n-doping of the as-synthesized material. Two distinct transitions in the spectral regime associated with the C exciton are found, which overlap into a broad signal upon filling the conduction band. In contrast to oxidation, the reduction of the nanosheets is largely reversible, enabling potential applications for reductive electrocatalysis. This work demonstrates that EMAS is a highly sensitive tool for determining the electronic structure of thin films with a few nanometer thicknesses and that colloidal chemistry affords high-quality transition metal dichalcogenide nanosheets with an electronic structure comparable to that of exfoliated samples.     

The structure-function relationship of the lipases from Pseudomonas aeruginosa and Bacillus subtilis

Within the BRIDGE T-project on lipases we investigate the structure-functionrelationships of the lipases from Bacillus subtilis and Pseudomonasaeruginosa. Construction of an overproducing Bacillus. strainallowed the purification of > 100 mg lipase from 30 l culturesupernatant. After testing a large variety of crystallizationconditions, the Bacillus lipase gave crystals of reasonablequality in PEG-4000 (38-45%), Na₂SO₄ and octyl-ß-glucosideat 22°C, pH 9.0. A 2.5 Å; dataset has been obtainedwhich is complete from 15 to 2.5 A resolution. P.aeruginosawild-type strain PAC1R was fermented using conditions of maximumlipase production. More than 90% of the lipase was cell boundand could be solubilized by treatment of the cells with TritonX-100. This permitted the purification of 50 mg lipase. So far,no crystals of sufficient quality were obtained. Comparisonof the model we built for the Pseudomonas lipase, on the basisof sequences and structures of various hydrolases which werefound to possess a common folding pattern (/ß hydrolasefold), with the X-ray structure of the P.glumae lipase revealedthat it is possible to correctly build the structure of thecore of a protein even in the absence of obvious sequence homologywith a protein of known 3-D structure.     

Bearing witness to uncorroborated trauma: The clinician's development of reflective belief.

Clinicians should not reflexively accept or reject as fact a client's initial report of uncorroborated abuse. However, by maintaining a neutral stance, clinicians may fall short of therapeutic honesty and transparency, may fail to promote reality testing, and may not perform the necessary step of bearing witness to the client's victimization. Using a case of dissociative identity disorder, this article proposes the careful development and sharing of the clinician's reflective belief in the (in)validity of reported trauma. This process may assist clients in (a) reclaiming a sense of integrated personal narrative memory and identity, (b) correcting cognitive distortions, or (c) both. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimization of fixed time polling schemes

This paper is concerned with the problem of deriving efficient operational rules for polling queues according to a fixed time polling scheme. A fixed time polling scheme specifies not only the visit order of the queues, but also the starting time for each visit. This problem arose from the need to efficiently collect files with call records from telecommunication switches. Using a simple approximation for the mean waiting times in a polling system with a non-cyclic visit order of the queues, we present an approach to the problem of minimizing a weighted sum of the mean waiting times at the various queues. This approach is tested via numerical experiments that are partly based on real network data.Part of O.J.B.'s research was supported by the European Grant BRA-QMIPS of CEC DG XIII.