Spiking Neurons Learning Phase Delays

Time differences between the two ears are an important cue for animals to azimuthally locate a sound source. The first binaural brainstem nucleus, in mammals the medial superior olive, is generally believed to perform the necessary computations. Its cells are sensitive to variations of interaural time differences of about 10 μs. The classical explanation of such a neuronal time-difference tuning is based on the physical concept of delay lines. Recent data, however, are inconsistent with a temporal delay and rather favor a phase delay. By means of a biophysical model we show how spike-timing-dependent synaptic learning explains precise interplay of excitation and inhibition and, hence, accounts for a physical realization of a phase delay

Filmed Architecture: The Nature of Vision

By researching the methods, technologies, theories, and criticism of motion film, one can begin to gain an understanding of these phenomena. Tha language of film becomes apparent, and can then be used in architectural discourse. How can these methods and techniques begin to translate into the discipline of architecture? What can the discipline gain from them In what capacity can we begin to augment their affects on our perception of architecture, form, reality, and space

Presence and localization of a 30-kDa basic fibroblast growth factor-like protein in rodent testes

We have used a recently characterized rabbit antiserum against basic fibroblast growth factor (bFGF), which recognizes various forms of bFGF, to examine the presence and localization of bFGF in the testes of adult rats and mice and the 5-day-old rat. In Western blots of testicular homogenates of adult rats and mice and immature rats, immunoreactive single bands at approximately 30 kDa were detected. Immunocytochemistry revealed specific staining restricted to the tubular compartment. In 5-day-old rat testes, prespermatogonia were immunoreactive. The cytoplasm of pachytene spermatocytes was heavily stained in the adult testes of both species. Staining of these cells became evident around stage IV/V, was prominent in stage VII through IX and declined about stage XII/XIII (rat) or X-XI (mouse). Staining was seen in type A spermatogonia and in elongating spermatids in their cytoplasmatic lobes and along their flagellae. Sertoli cells were unstained. We propose that the pluripotential growth factor bFGF could be involved in the regulation of germ cell proliferation and differentiation in the adult and immature testis

Runaway electrification of friable self-replicating granular matter

We establish that the nonlinear dynamics of collisions between particles favors the charging of a insulating, friable, self-replicating granular material that undergoes nucleation, growth, and fission processes; we demonstrate with a minimal dynamical model that secondary nucleation produces a positive feedback in an electrification mechanism that leads to runaway charging. We discuss ice as an example of such a self-replicating granular material: We confirm with laboratory experiments in which we grow ice from the vapor phase in situ within an environmental scanning electron microscope that charging causes fast-growing and easily breakable palm-like structures to form, which when broken off may form secondary nuclei. We propose that thunderstorms, both terrestrial and on other planets, and lightning in the solar nebula are instances of such runaway charging arising from this nonlinear dynamics in self-replicating granular matter

The Seasonality of Oxygen and Hydrogen Isotopes of Rain, Stream and Groundwater in Fredericksburg, VA

Stable isotopes of oxygen and hydrogen, δ18O and δD, are tracers of climatic changes within the hydrologic cycle, and thus are a potential link in the relationship between climate-influenced changes to the hydrologic cycle and modern and paleoenvironments. Studies have shown that the isotopic content of surface water and groundwater parallel meteoric water (e.g. Dutton et al., 2005), a relationship expected to be reflected in marine paleoclimate archives, such as those from the Chesapeake Bay, which are sensitive to freshwater input from rivers (e.g. LeGrande and Schmidt, 2009). In this study, we establish a baseline of isotopic composition of precipitation, stream, and groundwater in Fredericksburg, Virginia, to study the seasonality of δ18O and δD within the water. We have found precipitation in winter months to be more depleted in heavy isotopes than in warmer months, indicating the influence of temperature on isotopic abundance. Periods of high rainfall frequency result in greater variability of the δ18O and δD of stream water; however, periods of prolonged dryness resulted in deviations of this trend due to high rates of evaporation and the inflow groundwater into the stream. This work will provide the foundation of using δ18O and δD of meteoric water to study changing precipitation patterns as climate changes in the local Fredericksburg, VA region, as well as understanding the controls of the δ18O and δD of surface water for more robust interpretations from proxy records in regional paleoclimate studies

Differential associations of APOE-epsilon 2 and APOE-epsilon 4 alleles with PET-measured amyloid-beta and tau deposition in older individuals without dementia

Purpose: To examine associations between the APOE-ε2 and APOE-ε4 alleles and core Alzheimer’s disease (AD) pathological hallmarks as measured by amyloid-β (Aβ) and tau PET in older individuals without dementia. Methods: We analyzed data from 462 ADNI participants without dementia who underwent Aβ ([18F]florbetapir or [18F]florbetaben) and tau ([18F]flortaucipir) PET, structural MRI, and cognitive testing. Employing APOE-ε3 homozygotes as the reference group, associations between APOE-ε2 and APOE-ε4 carriership with global Aβ PET and regional tau PET measures (entorhinal cortex (ERC), inferior temporal cortex, and Braak-V/VI neocortical composite regions) were investigated using linear regression models. In a subset of 156 participants, we also investigated associations between APOE genotype and regional tau accumulation over time using linear mixed models. Finally, we assessed whether Aβ mediated the cross-sectional and longitudinal associations between APOE genotype and tau. Results: Compared to APOE-ε3 homozygotes, APOE-ε2 carriers had lower global Aβ burden (βstd [95% confidence interval (CI)]: − 0.31 [− 0.45, − 0.16], p = 0.034) but did not differ on regional tau burden or tau accumulation over time. APOE-ε4 participants showed higher Aβ (βstd [95%CI]: 0.64 [0.42, 0.82], p < 0.001) and tau burden (βstd range: 0.27-0.51, all p < 0.006). In mediation analyses, APOE-ε4 only retained an Aβ-independent effect on tau in the ERC. APOE-ε4 showed a trend towards increased tau accumulation over time in Braak-V/VI compared to APOE-ε3 homozygotes (βstd [95%CI]: 0.10 [− 0.02, 0.18], p = 0.11), and this association was fully mediated by baseline Aβ. Conclusion: Our data suggest that the established protective effect of the APOE-ε2 allele against developing clinical AD is primarily linked to resistance against Aβ deposition rather than tau pathology

Triggering on Forward Physics

The feasibility is investigated of a dedicated trigger stream in the CMS trigger menu, with an output rate of cal O (1)~kHz on the First Level Trigger and cal O (1)~Hz on the High Level Trigger. By combining jet trigger information from the CMS calorimeter with information from the TOTEM Roman Pot detectors at 220 m distance from the interaction point, the default dijet trigger thresholds foreseen in the CMS trigger tables can be lowered substantially while respecting the CMS trigger bandwidth limits. The efficacy of the dedicated diffractive trigger stream is demonstrated for hard single-diffractive and double-Pomeron exchange events