Relative abundance of amphibians in forest canopy gaps of natural origin vs. timber harvest origin

Small-scale canopy gaps created by logging may retain adequate habitat structure to maintain amphibian abundance. We used pitfalls with drift fences to measure relative abundance of amphibians in 44 harvested gaps, 19 natural treefall gaps, and 36 closed-canopy forest plots. Metamorphs had relatively lower capture rates in large harvest gaps for Ambystoma maculatum, Lithobates catesbeianus, L. clamitans, and L. sylvaticus but we did not detect statistically significant (p < 0.1) differences among gap types for Lithobates palustris metamorphs. L. clamitans juveniles and L. sylvaticus juveniles and adults had relatively lower capture rates in large harvest gaps. For juvenile-adult A. maculatum, we caught relatively fewer individuals in all gap types than in closed-canopy areas. Some groups with overall lower capture rates (immature Plethodon cinereus, juvenile L. palustris) had mixed differences among gap types, and Notophthalmus viridescens (efts) and adult P. cinereus showed no differences among gap types. One species, L. clamitans, was captured more often at gap edges than gap centers. These results suggest that harvest gaps, especially small gaps, provided habitat similar to natural gaps for some, but not all, amphibian species or life-stages

Alignment Cube with One Diffractive Face

An enhanced alignment cube has been invented for use in a confined setting (e.g., a cryogenic chamber) in which optical access may be limited to a single line of sight. Whereas traditional alignment-cube practice entails the use of two theodolites aimed along two lines of sight, the enhanced alignment cube yields complete alignment information through use of a single theodolite aimed along a single line of sight. Typically, an alignment cube is placed in contact with a datum surface or other reference feature on a scientific instrument during assembly or testing of the instrument. The alignment cube is then used in measuring a small angular deviation of the feature from a precise required orientation. Commonly, the deviation is expressed in terms of rotations (Rx,Ry,Rz) of the cube about the corresponding Cartesian axes (x,y,z). In traditional practice, in order to measure all three rotations, it is necessary to use two theodolites aimed at two orthogonal faces of the alignment cube, as shown in the upper part of the figure. To be able to perform such a measurement, one needs optical access to these two faces. In the case of an alignment cube inside a cryogenic chamber or other enclosed space, the optical-access requirement translates to a requirement for two windows located along the corresponding two orthogonal lines of sight into the chamber. In a typical application, it is difficult or impossible to provide two windows. The present enhanced version of the alignment cube makes it possible to measure all three rotations by use of a single line of sight, thereby obviating a second window

CIRS-lite, a Fourier Transform Spectrometer for Low-Cost Planetary Missions

Passive spectroscopic remote sensing of planetary atmospheres and surfaces in the thermal infrared is a powerful tool for obtaining information about surface and atmospheric temperatures, composition, and dynamics (via the thermal wind equation). Due to its broad spectral coverage, the Fourier transform spectrometer (FTS) is particularly suited to the exploration and discovery of molecular species. NASA's Goddard Space Flight Center (GSFC) developed the CIRS (Composite Infrared Spectrometer) FTS for the NASA/ESA Cassini mission to the Saturnian system. CIRS observes Saturn, Titan, icy moons such as Enceladus, and the rings in thermal self-emission over the spectral range of 7 to 1000 ell11. CIRS has given us important new insights into stratospheric composition and jets on Jupiter and Saturn, the cryo-geyser and thermal stripes on Enceladus, and the winter polar vortex on Titan. CIRS has a mass of 43 kg, contrasted with the earlier GSFC FTS, pre-Voyager IRIS (14 kg). Future low-cost planetary missions will have very tight constraints on science payload mass, thus we must endeavor to return to IRIS-level mass while maintaining CIRS-level science capabilities ("do more with less"). CIRS-lite achieves this by pursuing: a) more sensitive infrared detectors (high Tc superconductor) to enable smaller optics. b) changed long wavelength limit from 1000 to 300 microns to reduce diffraction by smaller optics. c) CVD (chemical vapor deposition) diamond beam-splitter for broad spectral coverage. d) single FTS architecture instead of a dual FTS architecture. e) novel materials, such as single crystal silicon for the input telescope primary

Computation of Symmetric Discrete Cosine Transform Using Bakhvalov's Algorithm

A number of algorithms for recursive computation of the discrete cosine transform (DCT) have been developed recently. This paper presents a new method for computing the discrete cosine transform and its inverse using Bakhvalov's algorithm, a method developed for evaluation of a polynomial at a point. In this paper, we will focus on both the application of the algorithm to the computation of the DCT-I and its complexity. In addition, Bakhvalov s algorithm is compared with Clenshaw s algorithm for the computation of the DCT

Long-Distance Axon Regeneration Promotes Recovery of Diaphragmatic Respiratory Function after Spinal Cord Injury.

Compromise in inspiratory breathing following cervical spinal cord injury (SCI) is caused by damage to descending bulbospinal axons originating in the rostral ventral respiratory group (rVRG) and consequent denervation and silencing of phrenic motor neurons (PhMNs) that directly control diaphragm activation. In a rat model of high-cervical hemisection SCI, we performed systemic administration of an antagonist peptide directed against phosphatase and tensin homolog (PTEN), a central inhibitor of neuron-intrinsic axon growth potential. PTEN antagonist peptide (PAP4) robustly restored diaphragm function, as determined with electromyography (EMG) recordings in living SCI animals. PAP4 promoted substantial, long-distance regeneration of injured rVRG axons through the lesion and back toward PhMNs located throughout the C3-C5 spinal cord. These regrowing rVRG axons also formed putative excitatory synaptic connections with PhMNs, demonstrating reconnection of rVRG-PhMN-diaphragm circuitry. Lastly, re-lesion through the hemisection site completely ablated functional recovery induced by PAP4. Collectively, our findings demonstrate that axon regeneration in response to systemic PAP4 administration promoted recovery of diaphragmatic respiratory function after cervical SCI

Mind the gap: Treefalls as drivers of parental trade-offs

Tree-fall gaps are small-scale disturbances whose formation, colonization, and role in forest dynamics are well documented, but whose effects on animal ecology are still greatly overlooked, except for studies comparing species richness of gaps 6+ months old to that in the closed canopy. Other factors associated with the invasion of fresh tree-fall gaps such as animal breeding adaptations have been largely neglected. I studied the immediate (within hours and days) arrival of the poison frog Dendrobates tinctorius in new tree-fall gaps to examine the dynamics of their invasion in relation to tadpole rearing. I found that rearing sites are occupied sooner and tadpoles deposited at higher rates in fresh gaps than in the closed forest, but that the rate of cannibalism is also much greater in the former. This suggests that invading new tree-fall gaps can be the best parental decision when parents arrive early because they get access to fresh, high-quality resources, but it could be to the detriment of the offspring if parents arrive late, because of overcrowding and cannibalism. These results highlight the importance of studying the earliest stages of invasions in order to have a better understanding of the composition of communities in disturbed ecosystems at later successional stages.peerReviewe