An investigation of liquid carryover and sample residual for a high-throughput flow cytometer sample delivery system

The phenomenon of intersample contamination in air-segmented continuous-flow assays has been studied for many years, and new uses are being found for these sampling techniques every day. One application that has been developed recently employs a flow cytometer to conduct high-throughput screening assays of biological compounds. We have explored the sources of intersample contamination in the system and shown how methods developed previously can be applied to describe these phenomena. Using a simple model, we were able to accurately measure liquid film thickness in the sample tubing and demonstrate the effects of intersample contamination in a flow cytometer assay. Also, measures have been taken to reduce the level of intersample contamination in cytometric screening assays, helping to make the system a more viable tool for drug screening applications.     

3D Motion recovery via affine Epipolar geometry

Algorithms to perform point-based motion estimation under orthographic and scaled orthographic projection abound in the literature. A key limitation of many existing algorithms is that they operate on the minimum amount of data required, often requiring the selection of a suitable minimal set from the available data to serve as a local coordinate frame. Such approaches are extremely sensitive to errors and noise in the minimal set, and forfeit the advantages of using the full data set. Furthermore, attention is seldom paid to the statistical performance of the algorithms.We present a new framework that allowsall available features to be used in the motion computations, without the need to select a frame explicitly. This theory is derived in the context of theaffine camera, which preserves parallelism and generalises the orthographic, scaled orthographic and para-perspective models. We define the affine epipolar geometry for two such cameras, giving the fundamental matrix in this case. The noise resistant computation of the epipolar geometry is discussed, and a statistical noise model constructed so that confidence in the results can be assessed.The rigid motion parameters are then determineddirectly from the epipolar geometry, using the novel rotation representation of Koenderink and van Doorn (1991). The two-view partial motion solution comprises the scale factor between views, the projection of the 3D axis of rotation and the cyclotorsion angle, while the addition of a third view allows the true 3D rotation axis to be computed (up to a Necker reversal). The computed uncertainties in these parameters permit optimal estimates to be obtained over time by means of a linear Kalman filter. Our theory extends work by Huang and Lee (1989), Harris (1990), and Koenderink and van Doorn (1991), and results are given on both simulated and real data.     

Juice-associated outbreaks of human illness in the United States, 1995 through 2005

Outbreaks of illness associated with consumption of fruit juice have been a growing public health problem since the early 1990s. In response to epidemiologic investigations of outbreaks in which juice was implicated, the U.S. Food and Drug Administration implemented process control measures to regulate the production of fruit juice. The final juice regulation, which became effective in 2002, 2003, and 2004, depending on the size of the business, requires that juice operations comply with a hazard analysis critical control point (HACCP) plan. The Centers for Disease Control and Prevention (CDC) receives reports of food-associated outbreaks of illness. We reviewed fruit juice-associated outbreaks of illness reported to the CDC's Foodborne Outbreak Reporting System. From 1995 through 2005, 21 juice-associated outbreaks were reported to CDC; 10 implicated apple juice or cider, 8 were linked to orange juice, and 3 involved other types of fruit juice. These outbreaks caused 1,366 illnesses, with a median of 21 cases per outbreak (range, 2 to 398 cases). Among the 13 outbreaks of known etiology, 5 were caused by Salmonella, 5 by Escherichia coli O157:H7, 2 by Cryptosporidium, and one by Shiga toxin-producing E. coli O111 and Cryptosporidium. Fewer juice-associated outbreaks have been reported since the juice HACCP regulation was implemented. Some juice operations that are exempt from processing requirements or do not comply with the regulation continue to be implicated in outbreaks of illness.     

Mechanisms of tubulin modification by phosphatidylcholine hydroperoxides

The interaction of lipid peroxides with cellular proteins has been postulated to contribute to cellular aging. A potential target for such effects is tubulin, the building block of microtubules. We examined the concentration-dependent effects of phosphatidylcholine hydroperoxides on the ability of tubulin to polymerize into microtubules. The results demonstrated that even very low concentrations of peroxides were sufficient to interfere with the tubulin and, therefore, the microtubule function. Decreased tubulin activity (as measured by tubulin GTPase activity) showed correlation with the modification of methionine and cysteine in tubulin and a change in the tubulin conformational state as indicated by fluorescence and ultraviolet spectroscopic measurements. As no effect on electric conductivity was observed, indicating that modulation of ionic binding was not involved, the interaction mechanism may be a hydrophobic one.     

Technologist engagement with risk management practices during systems development? Approaches,effectiveness and challenges

The inability to engage with systems risk during the development of integrated socio-technical systems presents a real threat to global and local socio-economic stability. Current theories on system risk engagement are driven by a functionalist orthodoxy. Accordingly, risk management is either non-existent, done in parallel to other development activity, or used by organisations as an instrument of control. Systems risk management needs to be addressed at the source of the problem: the systems engineering process. This paper addresses the predominant failure to appropriately engage with systems risk during development. It provides, with respect to the theoretical dimensions, a diversity of risk perspectives, complexity and socio-technical systems theory. A broad literature review on different risk concepts, risk management perspectives and organisational paradigms (functionalist, interpretive, radical humanist and radical structuralist) is also presented. In order to overcome a lack of a holistic and reflective risk management approach to systems development, this paper sketches an integrated soft systems methodology approach which can be used for engaging with systems risk during systems development.     

Upper extremity hemodynamics and sensation with backpack loads

Heavy backpacks are often used in extreme environments, for example by military during combat, therefore completion of tasks quickly and efficiently is of operational relevance. The purpose of this study was to quantify hemodynamic parameters (brachial artery Doppler and microvascular flow by photoplethysmography; tissue oxygenation by near-infrared spectroscopy; arterial oxygen saturation by pulse oximeter) and sensation in upper extremities and hands (Semmes-Weinstein monofilament test and 2-point discrimination test) while wearing a loaded backpack (12 kg) in healthy adults for 10 min. All values were compared to baseline before wearing a backpack. Moderate weight loaded backpack loads significantly decreased upper extremity sensation as well as all macrovascular and microvascular hemodynamic values. Decreased macrovascular and microvascular hemodynamics may produce neurological dysfunction and consequently, probably affect fine motor control of the hands.     

Treatment of Department of Veterans Affairs primary care patients with posttraumatic stress disorder.

Posttraumatic stress disorder (PTSD) is common among Veterans Affairs (VA) primary care patients and may be managed via multiple treatment pathways. Using the Behavioral Model of Health Service Use (Anderson, 1995), this retrospective study based on medical chart review examined factors associated with three types of mental health treatment: intervention by a 1) primary care provider (PCP), 2) primary care-mental health integration (PC-MHI) provider, and 3) specialty mental health (SMH) provider. A second goal was to describe PTSD treatment services for patients not receiving SMH by detailing the content of mental health treatment provided by PCPs and PC-MHI providers. Electronic medical record data for a five year time period for 133 Veterans were randomly selected for review from a population 6,637 primary care patients with PTSD. Results indicated that the evaluated needs of participants (i.e., number of unique medical and psychiatric disorders) were associated with Veterans receiving more intensive services (i.e., SMH). PCPs commonly addressed patients' mental health concerns, but patients often declined referrals for mental health treatment. PC-MHI consultations most often focused on medication management and supportive psychotherapy. (PsycINFO Database Record (c) 2011 APA, all rights reserved)