15 research outputs found
Psychometric Curve and Behavioral Strategies for Whisker-Based Texture Discrimination in Rats
The rodent whisker system is a major model for understanding neural mechanisms for tactile sensation of surface texture (roughness). Rats discriminate surface texture using the whiskers, and several theories exist for how texture information is physically sensed by the long, moveable macrovibrissae and encoded in spiking of neurons in somatosensory cortex. However, evaluating these theories requires a psychometric curve for texture discrimination, which is lacking. Here we trained rats to discriminate rough vs. fine sandpapers and grooved vs. smooth surfaces. Rats intermixed trials at macrovibrissa contact distance (nose >2 mm from surface) with trials at shorter distance (nose <2 mm from surface). Macrovibrissae were required for distant contact trials, while microvibrissae and non-whisker tactile cues were used for short distance trials. A psychometric curve was measured for macrovibrissa-based sandpaper texture discrimination. Rats discriminated rough P150 from smoother P180, P280, and P400 sandpaper (100, 82, 52, and 35 µm mean grit size, respectively). Use of olfactory, visual, and auditory cues was ruled out. This is the highest reported resolution for rodent texture discrimination, and constrains models of neural coding of texture information
The effect of spent bleaching earth ageing process on its physicochemical and microbial composition and its potential use as a source of fatty acids and triterpenes
NEUTRON TIME-OF-FLIGHT FACILITY AT THE UNIVERSITY-OF-SAO-PAULO 8UD PELLETRON TANDEM ACCELERATOR
164229330
Co-58: Structure of an odd-odd nucleus in the pf shell
High-spin states in the odd-odd
58
Co nucleus have been studied with the fusion-evaporation reaction
51
V(
10
B
,p
2
n
) using the
γ
-spectrometer Saci-Perere. Thirty-six new excited states up to spin 11
+
and an
excitation energy of 8.0 MeV have been observed, which are connected by 46
γ
-ray transitions. Transition
probabilities for 14 excited states were measured through the Doppler-shift attenuation method. The results are
compared with shell-model calculations using the GXPF1 effective interaction, developed for use in the pf shell.
These results were interpreted by considering particle-hole excitations with respect to the doubly magic
N
=
Z
=
28 core.status: publishe
Nuclear structure of the odd-odd nucleus Co-58
The odd–odd
58
Co nucleus has been studied with the
51
V(
10
B, p2
n
) reaction
at 33 MeV and 36 MeV incident energy using the
γ
-spectrometer Saci-Perer
ˆ
e.
Excited states up to 8.0 MeV and spin up to 11
+
have been observed. DSAM
lifetimes for 13 excited states were measured. The results are compared to
shell model calculations using the GXPF1 effective interaction, developed for
use in the fp shell.status: publishe
High-K band in Gd-140
High-spin states in the neutron-deficient140Gd nucleus have been studied with the 92Mo(54Fe,alpha2p) reaction at a beam energy of 240 MeV. The level scheme of 140Gd was considerably extended from what was previously known. In this work we concentrate on one of the 9 bands observed, which presents relatively strong M1 transitions and negligible signature splitting, and has an isomeric band-head, indicating a strongly coupled or high-K configuration. We compare this band to the Kpi = 8- bands observed in N=74 isotones and propose a similar configuration assignment, but with a somewhat larger deformation