Sensory gaze stabilization in echolocating bats.

Sensing from a moving platform is challenging for both man-made machines and animals. Animals' heads jitter during movement, so if the sensors they carry are not stabilized, any spatial estimation might be biased. Flying animals, like bats, seriously suffer from this problem because flapping flight induces rapid changes in acceleration which moves the body up and down. For echolocating bats, the problem is crucial. Because they emit a sound to sense the world, an unstable head means sound energy pointed in the wrong direction. It is unknown how bats mitigate this problem. By tracking the head and body of flying fruit bats, we show that they stabilize their heads, accurately maintaining a fixed acoustic-gaze relative to a target. Bats can solve the stabilization task even in complete darkness using only echo-based information. Moreover, the bats point their echolocation beam below the target and not towards it, a strategy that should result in better estimations of target elevation.

Results and complications after living related kidney transplantation in Hungary: 30 years' experience.

The number of patients suffering from kidney disorders is increasing the need for kidney transplantation. Kidneys originating from living donors (LD) show substantially better results than those originating from cadaveric donors (CD). We performed 3000 kidney transplantations between November 1973 and December 2007, including 154 from LD (5.13%). The early kidney function as measured by the delta creatinine clearance was significantly better among the LD group (P < .001). There was no significant difference in the immunologic data between the LD and the CD groups (P = .047). Four years after transplantation the glomerular filtration rate (GFR) and the serum creatinine level treated to be better among the LD group with tacrolimus versus cyclosporine immunosuppression (P = .089). In the LD group, the acute rejection rate was lower with tacrolimus- versus cyclosporine based immunosuppression (P = .014).

Data-Driven Haptic Rendering-From Viscous Fluids to Visco-Elastic Solids.

In this article we present extensions of our earlier work on data-driven haptic rendering. Haptic feedback is generated directly by interpolating measured data. The selection of appropriate data dimensions is guided by the structure of the generalized Maxwell model. Material elasticity and viscosity are reproduced, including transient material effects like stress relaxation. All these properties can be nonlinear and mutually dependent. Besides visco-elastic bodies, we also apply our method to viscous fluids. We present results for several materials and compare the errors of the interpolated forces with perceptual thresholds reported in the literature. Moreover, we examine how these errors behave if different subjects perform the recordings on which the data-driven haptic feedback is based.

Morphological study of the spinal canal content for subarachnoid endoscopy.

STUDY DESIGN AND OBJECTIVE: This study was designed to examine the morphology of the spinal dural sac and contents, using magnetic resonance imaging in order to define the inner geometrical dimensions that confine the manoeuvre of an endoscope inserted in the lumbar region and along the thoracic and cervical spine. BACKGROUND: The morphology of the spine has been studied since the development of myelography. However, most studies have measured the diameters of the spinal cord only, not the size of the subarachnoid space. In addition, the few studies available on the subarachnoid space have focused on the cervical spine, leaving a near-complete dearth of data on the subarachnoid space dimensions along the thoracic spine. METHODS: Based on MRI images of the spine from 42 patients, the dimensions of the spinal cord, dural sac, and subarachnoid space were measured at mid-vertebral and inter-vertebral disc levels. RESULTS: It was found that at each selected transverse level, the subarachnoid space tends to be symmetrical on the right and left sides of the cord, and measures 2.5 mm on average. However, the posterior and anterior segments, measured on the mid-sagittal plane, are generally asymmetrical and vary widely in size, ranging from 1 to 5 mm. These measurements match those found in previous studies, where these are available. The coefficient of variance for the dimensions of the subarachnoid space is as high as 42.4%, while that for the dimensions of the spinal cord is 10-15%. CONCLUSIONS: The findings presented here expand our knowledge of the spinal canal's morphology, and show that an endoscope designed to travel within the subarachnoid space must be smaller than 2.5 mm in diameter.