Kinetic masks: a new approach and device for dispersing biologically relevant fluids

The controlled dispersion of fluids, particularly biologically relevant solutions in micro-volumes, is of high practical interest in biotechnology and medicine. Pharmaceutical test assays, for example, need a method for the fast and defined deposition of fluid samples. Most current micro-dispensing methods, i.e. contact-based pin printing, have problems such as time delays, limited dosing velocity, minimum volume or high interference that limit biological applications. Spraying techniques suffer from a lack of reproducibility; a defined deposition of samples on targets is not possible. Here, we introduce a new method for the parallel and spatially defined dispersion of many micro-volumes that overcomes disadvantages of common micro-dispensers. The overall approach is that a fluid drop, produced by a droplet generator, falls on a free trajectory with a defined kinetic energy, and is split by a masking unit placed perpendicular to the flight direction into at least two smaller droplets (Zimmermann et al. in Method and device for dosing fluid media, WO/2002/102515, Germany, 2002). On the target, the resulting droplets form reproducible patterns, which are enlarged and scalable images of the grid pattern. Possible applications for this method are non-contact cell patterning, cell encapsulation, cryopreservation and fast mixing processes in micro-volumes. Here, we use this method for the direct and defined parallel positioning of cell suspensions on specific substrates, which can be useful for test assays, tissue engineering and cryopreservation.     

Interactive display of isosurfaces with global illumination

In many applications, volumetric data sets are examined by displaying isosurfaces, surfaces where the data, or some function of the data, takes on a given value. Interactive applications typically use local lighting models to render such surfaces. This work introduces a method to precompute or lazily compute global illumination to improve interactive isosurface renderings. The precompiled illumination resides in a separate volume and includes direct light, shadows, and intersections. Using this volume, interactive globally illuminated renderings of isosurfaces become feasible while still allowing dynamic manipulation of lighting, viewpoint and isovalue.     

Engineering better wheelchairs to enhance community participation.

With about 2.2 million Americans currently using wheeled mobility devices, wheelchairs are frequently provided to people with impaired mobility to provide accessibility to the community. Individuals with spinal cord injuries, arthritis, balance disorders, and other conditions or diseases are typical users of wheelchairs. However, secondary injuries and wheelchair-related accidents are risks introduced by wheelchairs. Research is underway to advance wheelchair design to prevent or accommodate secondary injuries related to propulsion and transfer biomechanics, while improving safe, functional performance and accessibility to the community. This paper summarizes research and development underway aimed at enhancing safety and optimizing wheelchair design.     

Recent Life Events Preceding Suicide Attempts in a Personality Disorder Sample: Findings From the Collaborative Longitudinal Personality Disorders Study.

Few studies have examined the relationship between life events, suicide attempts, and personality disorders (PDs), in spite of the strong associations between PDs and suicidal behavior, and the poor coping strategies often exhibited by these individuals. The authors examined whether participants with PDs who attempted suicide during the first 3 years of a prospective, longitudinal study were more likely to experience specific life events in the month during and preceding the suicide attempt. Of 489 participants with PDs, 61 attempted suicide during the 3-year, follow-up interval. Results indicated that negative life events, particularly those pertaining to love-marriage or crime-legal matters, were significant predictors of suicide attempts, even after controlling for baseline diagnoses of borderline PD, major depressive disorders, substance use disorders, and a history of childhood sexual abuse. Therefore, certain types of negative life events are unique risk factors for imminent suicide attempts among individuals with PDs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A model for volume lighting and modeling

Direct volume rendering is a commonly used technique in visualization applications. Many of these applications require sophisticated shading models to capture subtle lighting effects and characteristics of volumetric data and materials. For many volumes, homogeneous regions pose problems for typical gradient-based surface shading. Many common objects and natural phenomena exhibit visual quality that cannot be captured using simple lighting models or cannot be solved at interactive rates using more sophisticated methods. We present a simple yet effective interactive shading model which captures volumetric light attenuation effects that incorporates volumetric shadows, an approximation to phase functions, an approximation to forward scattering, and chromatic attenuation that provides the subtle appearance of translucency. We also present a technique for volume displacement or perturbation that allows realistic interactive modeling of high frequency detail for both real and synthetic volumetric data.     

Associations in the Course of Personality Disorders and Axis I Disorders Over Time.

In this study, the authors examined time-varying associations between schizotypal (STPD), borderline (BPD), avoidant (AVPD), or obsessive-compulsive (OCPD) personality disorders and co-occurring Axis I disorders in 544 adult participants from the Collaborative Longitudinal Personality Disorders Study. The authors tested predictions of specific longitudinal associations derived from a model of crosscutting psychobiological dimensions (L. J. Siever & K. L. Davis, 1991) with participants with the relevant Axis I disorders. The authors assessed participants at baseline and at 6-, 12-, and 24-month follow-up evaluations. BPD showed significant longitudinal associations with major depressive disorder and posttraumatic stress disorder. AVPD was significantly associated with anxiety disorders (specifically social phobia and obsessive-compulsive disorder). Two of the four personality disorders under examination (STPD and OCPD) showed little or no association with Axis I disorders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two-Year Stability and Change of Schizotypal, Borderline, Avoidant, and Obsessive-Compulsive Personality Disorders.

The authors examined the stability of schizotypal (STPD), borderline (BPD), avoidant (AVPD) and obsessive-compulsive (OCPD) personality disorders (PDs) over 2 years of prospective multiwave follow-up. Six hundred thirty-three participants recruited at 4 collaborating sites who met criteria for 1 or more of the 4 PDs or for major depressive disorder (MOD) without PD were assessed with semistructured interviews at baseline, 6, 12, and 24 months. Lifetable survival analyses revealed that the PD groups had slower time to remission than the MDD group. Categorically, PD remission rates range from 50% (AVPD) to 61% (STPD) for dropping below diagnostic threshold on a blind 24-month reassessment but range from 23% (STPD) to 38% (OCPD) for a more stringent definition of improvement. Dimensionally, these findings suggest that PDs may be characterized by maladaptive trait constellations that are stable in their structure (individual differences) but can change in severity or expression over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fluxing Agents on Ceramification of Composites of MgO-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript>/Boron Phenolic Resin

Fluxing agents of zinc borate, antimony oxide, galss frit A and glass frit B, with different melting or softening point temperatures, were added into MgO-Al₂O₃-SiO₂/boron phenol formaldehyde resin (MAS/BPF) composites to lower the formation temperature of eutectic liquid phase and promote the ceramification of ceramifiable composites. The effects of fluxing agents on the thermogravimetric properties, phase evolution, and microstructure evolution of MAS / BPF composites were characterized by TG-DSC, XRD and SEM analyses. The results reveal that the addition of a fluxing agent highly reduces the decomposition rate of MAS / BPF composites. Fluxing agents lower the formation temperatures of liquid phases of ceramifiable MAS / BPF composites obviously, and then promote the ceramification and densification process. The final residues of composites are ceramic surrounded by large amount of glass phases.     

A Systematic Structure–Activity Study of a New Type of Small Peptidic Transfection Vector Reveals the Importance of a Special Oxo-Anion-Binding Motif for Gene Delivery

We discovered a new class of artificial peptidic transfection vectors based on an artificial anion-binding motif, the guanidiniocarbonylpyrrole (GCP) cation. This new type of vector is surprisingly smaller than traditional systems, and our previous work suggested that the GCP group was important for promoting critical endosomal escape. We now present here a systematic comparison of similar DNA ligands featuring our GCP oxo-anion-binding motif with DNA ligands only consisting of naturally occurring amino acids. Structure–activity studies showed that the artificial binding motif clearly outperformed natural amino acids such as histidine, lysine, and arginine. It improved the ability to shuttle foreign genetic material into cells, yet successfully mediated endosomal escape. Also, plasmids that were complexed by our artificial ligands were stabilized against cytosolic degradation to some extent. This resulted in the successful expression of plasmid information (comparable to gold standards such as polyethyleneimine). Hence, our study clearly demonstrates the importance of the tailor-made GCP anion-binding site for efficient gene transfection.