Customizing MRI-Compatible Multifunctional Neural Interfaces through Fiber Drawing

Fiber drawing enables scalable fabrication of multifunctional flexible fibers that integrate electrical, optical, and microfluidic modalities to record and modulate neural activity. Constraints on thermomechanical properties of materials, however, have prevented integrated drawing of metal electrodes with low-loss polymer waveguides for concurrent electrical recording and optical neuromodulation. Here, two fabrication approaches are introduced: 1) an iterative thermal drawing with a soft, low melting temperature (T_m) metal indium, and 2) a metal convergence drawing with traditionally non-drawable high T_m metal tungsten. Both approaches deliver multifunctional flexible neural interfaces with low-impedance metallic electrodes and low-loss waveguides, capable of recording optically-evoked and spontaneous neural activity in mice over several weeks. These fibers are coupled with a light-weight mechanical microdrive (1 g) that enables depth-specific interrogation of neural circuits in mice following chronic implantation. Finally, the compatibility of these fibers with magnetic resonance imaging is demonstrated and they are applied to visualize the delivery of chemical payloads through the integrated channels in real time. Together, these advances expand the domains of application of the fiber-based neural probes in neuroscience and neuroengineering.     

Determining protein loop conformation using scaling-relaxation techniques

We recently developed a rapid loop closure algorithm in which bond lengths are scaled to constrain the ends of a segment to match a known distance and then gradually relaxed to their standard values, with boundary constraints maintained. Although the algorithm predicted the Zif286 zinc-finger loop to within approximately 2 A, it had a serious limitation that made its more general use tentative: it omitted the atomic environment of the loop. Here we report an extension of the algorithm to take into account the protein environment surrounding a given loop from the outset of the conformational search and show that it predicts structure with an efficiency and accuracy that could not be achieved without continuous environmental inclusion. The algorithm should be widely applicable to structure determination when complete experimental information is unavailable.     

Prophylactic effects of recombinant human superoxide dismutase in neonatal lung injury

To determine if recombinant human Cu-Zn superoxide dismutase (rhSOD) would prevent acute lung injury caused by hyperoxia and barotrauma, 26 newborn piglets were studied. Ten piglets were hyperventilated (arterial PCO2 15-20 Torr) with 100% O2 for 48 h. A second group received identical treatment for 4 h (n = 2) or 48 h (n = 8) but was given 5 mg/kg of rhSOD intratracheally at time 0. Six piglets were normally ventilated (arterial PCO2 40-45 Torr) for 48 h with 21% O2. Pulmonary function and tracheal aspirates were examined at time 0 and at 24 and 48 h, and bronchoalveolar lavage was performed at 48 h. In piglets treated with hyperoxia and hyperventilation, lung compliance decreased 42%, and tracheal aspirates showed an increase in neutrophil chemotactic activity (32%), total cell counts (135%), elastase activity (93%), and albumin concentration (339%) over 48 h (P < 0.05). All variables were significantly lower in rhSOD-treated piglets and comparable to normoxic control values. Surfactant remained active in all groups. Immunohistochemistry demonstrated that at 48 h significant rhSOD was distributed homogeneously in terminal airways. Adding rhSOD to tracheal aspirates of hyperoxic hyperventilated piglets did not alter neutrophil chemotaxis, suggesting that rhSOD protected the lung by reducing the production of chemotactic mediators. Results indicate that acute lung injury caused by 48 h of hyperoxia and hyperventilation is significantly ameliorated by prophylactic intratracheal administration of rhSOD.     

The perimeter of a fuzzy set

In pattern recognition one often wants to measure the perimeters of regions in images. This is straightforward if the region is crisply defined, but if it is fuzzy, it is not obvious how its perimeter can be measured. This paper proposes a definition of perimeter for fuzzy subsets of the plane and shows that it reduces to the standard definition if the fuzzy subset is an ordinary subset. The isoperimetric inequality does not generalize to fuzzy subsets, but certain properties of the perimeters of convex sets do generalize to fuzzy perimeters of convex fuzzy subsets.     

3-D shape recovery using distributed aspect matching

An approach to the recovery of 3-D volumetric primitives from a single 2-D image is presented. The approach first takes a set of 3-D volumetric modeling primitives and generates a hierarchical aspect representation based on the projected surfaces of the primitives; conditional probabilities capture the ambiguity of mappings between levels of the hierarchy. From a region segmentation of the input image, the authors present a formulation of the recovery problem based on the grouping of the regions into aspects. No domain-independent heuristics are used; only the probabilities inherent in the aspect hierarchy are exploited. Once the aspects are recovered, the aspect hierarchy is used to infer a set of volumetric primitives and their connectivity. As a front end to an object recognition system, the approach provides the indexing power of complex 3-D object-centered primitives while exploiting the convenience of 2-D viewer-centered aspect matching; aspects are used to represent a finite vocabulary of 3-D parts from which objects can be constructed     

Determining plane orientation from specular reflectance

This paper describes methods of estimating the orientation of a planar surface from the shapes of the contours of constant brightness on the surface, using perspective projection. It is assumed that the illumination is from a distant point source in a known direction. Two reflectance models, proposed respectively by Horn and Pentland, are used.     

Recovery of temporal information from static images of handwriting

The problem of off-line handwritten character recognition has eluded a satisfactory solution for several decades. Researchers working in the area of on-line recognition have had greater success, but the possibility of extracting on-line information from static images has not been fully explored. The experience of forensic document examiners assures us that in many cases, such information can be successfully recovered.We outline the design of a system for the recovery of temporal information from static handwritten images. We provide a taxonomy of local, regional and global temporal clues which are often found in hand-written samples, and describe methods for recovering these clues from the image.We show how this system can benefit from obtaining a comprehensive understanding of the handwriting signal and a detailed analysis of stroke and sub-stroke properties. We suggest that the recovery task requires that we break away from traditional thresholding and thinning techniques, and we provide a framework for such analysis. We demonstrate how isolated temporal clues can reliably be extracted from this framework and propose a control structure for integrating the partial information.We show how many seemingly ambiguous situations can be resolved by the derived clues and our knowledge of the writing process, and provide several examples to illustrate our approach.The support of this research by the Ricoh Corporation is gratefully acknowledged.     

High-dose growth hormone treatment of short children born small for gestational age

The effect of GH administration was evaluated over 2 yr in 50 short, prepubertal, non-GH deficient children born small for gestational age, who had been randomly allocated to a group receiving no treatment or daily sc GH treatment at a dose of 0.2 or 0.3 IU/kg. At the start of the study, mean age was 5.2 yr, bone age was 4.0 yr, height SDS was -3.5, height velocity SDS was -0.8, weight SDS was -2.7, and body mass index SDS was -1.9. Catch-up growth was observed in none of the untreated and all of the treated children. The response to GH treatment included a near doubling of growth velocity and of weight gain and a mean height increment of more than 2 SDS. GH treatment was associated with a distinct acceleration of bone maturation. The differences between the growth responses evoked by the two GH doses were minor. The prepubertal GH-induced catch-up growth was associated with elevated serum concentrations of insulin, insulin-like growth factor-I, insulin-like growth factor binding protein-3, and osteocalcin, whereas insulin-like growth factor-II levels remained unaltered. GH treatment was well tolerated. In conclusion, high-dose GH administration over 2 yr is emerging as a potential therapy to increase the short stature that results from insufficient catch-up growth in young children born small for gestational age. The long-term impact of this approach remains to be delineated.