Further observations on the relationship of EMG and muscle force

Human skeletal muscle may be regarded as an electro-mechanical transducer. Its physiological input is a neural signal originating at the alpha motoneurons in the spinal cord and its output is force and muscle contraction, these both being dependent on the external load. Some experimental data taken during voluntary efforts around the ankle joint and by direct electrical stimulation of the nerve are described. Some of these experiments are simulated by an analog model, the input of which is recorded physiological soleus muscle EMG. The output is simulated foot torque. Limitations of a linear model and effect of some nonlinearities are discussed

New calibrations and time stability of the response of the INTERCAST CR-39

We present new calibrations of different production batches (from 1989 to 1999) of the INTERCAST CR-39, using the BNL-AGS 1 A GeV iron beam. The comparison with previous results, obtained with the 158 A GeV lead beam from the CERN-SPS shows that, while each production batch has a different calibration curve (mainly due to minor differences in the production conditions), the aging effect is negligible. We also tested the dependence of the CR-39 response from the time elapsed between exposure and analysis (fading effect). The fading effect, if present, is less than 10%. It may be compatible with the experimental uncertainties on the bulk etching rate vB.Comment: 9 pages, 4 EPS figures, .pdf file. Talk presented by M. Giorgini at the 20 Int. Conf. on Nuclear Tracks in Solids, Portoroz (Slovenia), Aug 28-Sep 1, 200

Meaurement of Cosmic Ray elemental composition from the CAKE balloon experiment

CAKE (Cosmic Abundances below Knee Energies) was a prototype balloon experiment for the determination of the charge spectra and of abundances of the primary cosmic-rays (CR) with Z$>$10. It was a passive instrument made of layers of CR39 and Lexan nuclear track detectors; it had a geometric acceptance of $\sim$0.7 m$^2$sr for Fe nuclei. Here, the scanning and analysis strategies, the algorithms used for the off-line filtering and for the tracking in automated mode of the primary cosmic rays are presented, together with the resulting CR charge distribution and their abundances.Comment: 5 pages, 8 figure

Fragmentation cross sections of 158 A GeV Pb ions in various targets measured with CR39 nuclear track detectors

We report the measurement of the fragmentation cross sections in high-energy nucleus-nucleus collisions using the 158 A GeV Pb beam from the CERN-SPS. The fragments have charges changed from that of the incident projectile nucleus by $\Delta Z=Z_{Pb}-Z_{frag}$, with 8 <\Delta Z <75. The targets range from polyethylene to lead. Charge identification is made with CR39 nuclear track detectors, measured with an automatic image analyzer system. The measured fragmentation cross sections are parameterized with an empirical relation in terms of the atomic mass of the target, and of the charge of the final fragment.Comment: 16 pages, 5 figure

Nuclear Track Detectors for Environmental Studies and Radiation Monitoring

Several improvements were made for Nuclear Track Detectors (NTDs) used for environmental studies and for particle searches. A new method was used to determine the bulk etch rate of CR39 and Makrofol NTDs. It is based on the simultaneous measurement of the diameter and of the height of etch-pit cones caused by relativistic heavy ions (158 A GeV Pb(82+) and In(49+) ions) and their fragments. The use of alcohol in the etching solution improves the surface quality of NTDs and it raises their thresholds. The detectors were used for the determination of nuclear fragmentation cross sections of Iron and Silicon ions of 1.0 and 0.41 GeV/nucleon. These measurements are important for the determination of doses in hadron therapy and for doses received by astronauts. The detectors were also used in the search of massive particles in the cosmic radiation, for the determination of the mass spectrum of cosmic rays and for the evaluation of Po(210) alpha decay and of natural radon concentrations.Comment: 7 pages, 5 EPS figures. Presented at the 10th Topical Seminar on Innovative Particle and Radiation Detectors, 1-5 October 2006, Siena, Ital

Bulk Etch Rate Measurements and Calibrations of Plastic Nuclear Track Detectors

New calibrations of CR39 and Makrofol nuclear track detectors have been obtained using 158 A GeV Pb (82+) and In (49+) ions; a new method for the bulk etch rate determination, using both cone height and base diameter measurements was developed. The CR39 charge resolution based on the etch-pit base area measurement is adequate to identify nuclear fragments in the interval 7 <= Z/beta <= 49. For CR39 the detection threshold is at REL~50 MeV cm^2/g, corresponding to a nuclear fragment with Z/beta~7. Base cone area distributions for Makrofol foils exposed to Pb (82+) ions have shown for the first time all peaks due to nuclear fragments with Z > 50; the distribution of the etched cone heights shows well separated individual peaks for Z/beta = 78 - 83 (charge pickup). The Makrofol detection threshold is at REL 2700 MeV cm^2/g, corresponding to a nuclear fragment with Z/beta~50.Comment: 11 pages, 5 EPS figures. Submitted to Nucl. Instr. Meth.

Emulsion pcr (Epcr) as a tool to improve the power of dgge analysis for microbial population studies

To the authors\u2019 knowledge, this is the first report of the use of emulsion-Polymerase chain reaction (e-PCR) coupled with denaturing gradient gel electrophoresis (DGGE) analysis. In the present work the effectiveness of ePCR in improving the power of the DGGE technique for microbial population studies was tested. Our results indicated that ePCR results in uniform amplification of several DNA molecules, overcoming the major limitations of conventional PCR, such as preferential amplification and DNA concentration dependence. Moreover, ePCR-DGGE resulted in higher sensitivity when compared to conventional PCR-DGGE methods used for studying microbial populations in a complex matrix. In fact, compared to conventional PCR, the DGGE profiles of ePCR products permitted the detection of a higher number of the species that were present in the tested sample