Transistor biased amplifier minimizes diode discriminator threshold attenuation

Transistor biased amplifier has a biased diode discriminator driven by a high impedance /several megohms/ current source, rather than a voltage source with several hundred ohms output impedance. This high impedance input arrangement makes the incremental impedance of the threshold diode negligible relative to the input impedance

Current-switching technique for analog pulse circuits

Circuit technique uses a signal diode as a series current-pass element. Technique is applied to the design of a biased amplifier circuit and a nanosecond-pulse stretcher circuit

Pulse stretcher has improved dynamic range and linearity

Current-switching pulse stretcher overcomes the diode nonlinearity and capacitive feedthrough of voltage switching diode-capacitor stretchers and lengthens nanosecond pulses so that their amplitude may be determined and extends the dynamic range of the pulse stretcher. The rise time of the output pulse in response to a step function is approximately 5 nanoseconds

Tunnel diode circuit used as nanosecond-range time marker

Simple tunnel diode time marker circuit determines the time at which an event occurs in a scintillation crystal. It is capable of triggering at voltages as low as the noise level of a 10-stage PM tube

Pulse-height defect due to electron interaction in dead layers of Ge/Li/ gamma-ray detectors

Study shows the pulse-height degradation of gamma ray spectra in germanium/lithium detectors to be due to electron interaction in the dead layers that exist in all semiconductor detectors. A pulse shape discrimination technique identifies and eliminates these defective pulses

An LC inventory based on representative and coherent farm types

There is a need for valid and representative data regarding the production, resource use and emissions from typical farming systems in Denmark for analysis of the environmental impact of different systems and as input to product oriented analyses such as Life Cycle Assess-ments of basic food items. An inventory of 31 farm types was constructed on the basis of 2138 farm accounts from 1999 selected and weighted to be representative for the Danish farming sector. The farm accounts were grouped according to the major soil types, the num-ber of standard working hours, the most important enterprise (dairy, pig, different cash crops) and the stocking rate (livestock units per hectare). For each group the account data on the average inputs and outputs, land use and herd structure was used to establish a farm type model with coherency between livestock production, total feed use, land use, yields, im-ported feed, home-grown feed, manure production, fertiliser use and crop production. The set of farm types were scaled up to national level thus representing the whole Danish agricul-tural sector for the included products. The sum of area and yield by crop, number and pro-duction by livestock type and the use of fertiliser, energy and concentrated feed was checked against national level statistics and corrected accordingly across all farm types. Resource use and emissions in each farm type was established using standard nutrient concentrations and models for nutrient cycling, energy use and emissions of e.g. ammonia, nitrous oxides and methane. For LCA the product oriented inventory was established using system expan-sion rather than allocations to account for the secondary enterprises in the livestock farm types. Data are made available on a web-based database and may be used for analyses of the primary production systems or as input for LCA across the whole production chain

Manganese-56 coincidence-counting facility precisely measures neutron-source strength

Precise measurement of neutron-source strength is provided by a manganese 56 coincidence-counting facility using the manganese-bath technique. This facility combines nuclear instrumentation with coincidence-counting techniques to handle a wide variety of radioisotope-counting requirements

Comment on "Formation of primordial black holes by cosmic strings"

We show that in a pioneering paper by Polnarev and Zembowicz, some conclusions concerning the characteristics of the Turok-strings are generally not correct. In addition we show that the probability of string collapse given there, is off by a large prefactor (~1000).Comment: 5 pages, LaTeX and 1 figure, postscript. To appear in PR

Cosmological Solution in M-theory on S^1/Z_2

We provide the first example of a cosmological solution of the Horava-Witten supergravity. This solution is obtained by exchanging the role of time with the radial coordinate of the transverse space to the five-brane soliton. On the boundary this corresponds to rotating an instanton solution into a tunneling process in a space with Lorentzian signature, leading to an expanding universe. Due to the freedom to choose different non-trivial Yang-Mills backgrounds on the boundaries, the two walls of the universe ( visible and hidden worlds) expand differently. However at late times the anisotropy is washed away by gravitational interactions.Comment: 10 pages, latex, no figur