White-light interferometric method for secure key distribution

A protocol for secure key distribution using classical light is proposed. The method relies on white-light interferometric measurements by one of the communicating parties and the random choice of delays by the other party. In this way, securely shared random keys are created, thereby enabling secure data transmission. In contrast to quantum key distribution, only classical waves are used. Single photons (and the practical problems associated with them) are avoided. The security of the method cannot be proven at the moment but different attacks are described and briefly analyzed.     

On the relationship between recall and recognition memory.

The relationship between recall and recognition has been a central topic for the study of memory. A test of alternative views about recall and recognition was arranged by studying amnesic patients. In amnesia, damage has occurred to a brain system important for declarative (conscious) memory, but skill learning, priming, and other forms of nonconscious memory are intact. Recall and recognition were found to be proportionately impaired in amnesic patients, and confidence ratings for the recognition judgments were commensurate with the level of impaired performance. The results are contrary to views that either recognition memory or associated confidence judgments are ordinarily supported significantly by nonconscious memory. The results favor the view that recall and recognition are related functions of declarative memory and equivalently dependent on the brain system damaged in amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fast digital hologram generation and adaptive force measurement in liquid-crystal-display-based holographic tweezers

Computer-generated holograms in conjunction with spatial light modulators (SLMs) offer a way to dynamically generate holograms that are adapted to specific tasks. To use the full dynamic capability of the SLM, the hologram computation should be very fast. We present a method that uses the highly parallel architecture of a consumer graphics board to compute analytical holograms in video real time. A precice characterization of the SLM (Holoeye LC-R-2500) and the adaption of its settings to our near-infrared application is necessary to guarantee an efficient hologram reconstruction. The benefits of a fast computation of adapted holograms and the application of an efficient SLM are demonstrated by measuring the trapping forces of holographic tweezers.     

Positioning of Noncooperative Objects by use of Joint Transform Correlation Combined with Fringe Projection

Automated assembly and quality control require reliable systems for the detection of the position and the orientation of complicated objects. Correlation methods are well suited, but they are affected by structured backgrounds, varying illumination conditions, and textured or dirty object surfaces. Using fringe projection to exploit the three-dimensional topography of objects, we improve the performance of a nonlinear joint transform correlator. Positioning of noncooperative objects with subpixel accuracy is demonstrated. Additionally, the tilt angle of an arbitrarily shaped object is measured by projection of object-adapted fringes that produce a homogeneous fringe pattern in the image plane. An accuracy of better than 1 degrees is achieved.     

Molecular analysis of bovine spongiform encephalopathy and scrapie strain variation

Five mouse scrapie strains, a mouse-passaged scrapie isolate derived from a field case in sheep in Germany, and 2 mouse-passaged bovine spongiform encephalopathy (BSE) isolates were analyzed by immunoblot in regards to banding patterns of proteinase K-digested pathologic prion proteins (PrPres). To obtain reliable results, the photo-imager technique was used for measurement of staining band intensities. Distinct and reproducible profiles were observed for the different strains or isolates. A British and a German BSE isolate were similar, suggesting the same source of infection. The German scrapie isolate resembled scrapie strain ME7, which has frequently been isolated from sheep scrapie in the past. In selected strains or isolates, no influence of the mouse lines used was observed on PrPres profiles, nor were brain region-specific differences apparent. This investigation suggests that PrPres glycotyping can be an invaluable tool for the in vitro differentiation of BSE and scrapie isolates.     

School barricaded captive-takings: An exploratory investigation of school resource officer responses.

School resource officers (SROs) are often the first responders to a school-based emergency. To date there is little research that investigates what, specifically, SROs do during a crisis. One type of school crisis is a barricaded captive-taking. This study reports on the reactions of three SROs who responded to a captive-taking event in their schools. The purpose was to begin developing categories in anticipation of validating a working model for psychologists and SRO responses. A content analysis in the grounded theory tradition was used to analyze their responses. A total of 15 categories were identified that help us understand what SROs did to respond to a school captive-taking. Implications for SROs and advancing psychological practice, strengths and limitations are addressed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Combination of scene-based and stochastic measurement for wide-field aberration correction in microscopic imaging

We report on a novel aberration correction technique that uses the sequential combination of two different aberration measurement methods to correct for setup-induced and specimen-induced aberrations. The advantages of both methods are combined and, thus, the measurement time is strongly reduced without loss of accuracy. The technique is implemented using a spatial-light-modulator-based wide-field microscope without the need for additional components (e.g., a Shack-Hartmann sensor). The aberrations are measured without a reference object by directly using the specimen to be imaged. We demonstrate experimental results for technical as well as biological specimens.