Results of a High Altitude Cosmic-Ray Survey Near the Magnetic Equator

Electroscope and Geiger counter observations have been taken with free balloons at geomagnetic latitudes of 3°, 17°, and 25°N. The most important results are as follows: (1) The Geiger counter technique with a single counter will give results very close to those obtained with the electroscope and of comparable accuracy. (2) Vertical coincidence measurements give rise to markedly different values for the relative amounts of incident energy at various latitudes, as compared with the electroscope or single counter data. (3) Within the experimental error, no difference was obtained between the vertical coincidence curves at 3° and 17°, and thus no new energy lies in the primary energy spectrum between the limits of 17 and 15 Bev. (4) This is direct evidence for a banded structure in the primary cosmic-ray spectrum. (5) Flights made with triple and quadruple coincidences, and also with counters arranged to record showers, showed that showers do not significantly affect the vertical coincidence measurements

A high speed Geiger-counter circuit

An improved Geiger-counter circuit is described which has the following characteristics: (1) It will respond to at least 2×10(5) particles per minute. (2) Easily obtainable resistances of not more than a few million ohms are used. (3) Consistency of operation is obtained since surface leakages and surface charges are unimportant. (4) The circuit will operate equally well with very small or very large counting tubes, and at either low or high counting rates. (5) The counts are independent of the voltage on the counter over a wide range. (6) A large pulse is obtained which makes possible the use of low values of resistance and capacity to the mixing tube in case several counters are used to count coincidents. (7) The circuit is simple, inexpensive to make and has given satisfactory performance on several different research problems at this Institute

Reduced tillage, but not organic matter input, increased nematode diversity and food web stability in European long‐term field experiments

Soil nematode communities and food web indices can inform about the complexity, nutrient flows and decomposition pathways of soil food webs, reflecting soil quality. Relative abundance of nematode feeding and life‐history groups are used for calculating food web indices, i.e., maturity index (MI), enrichment index (EI), structure index (SI) and channel index (CI). Molecular methods to study nematode communities potentially offer advantages compared to traditional methods in terms of resolution, throughput, cost and time. In spite of such advantages, molecular data have not often been adopted so far to assess the effects of soil management on nematode communities and to calculate these food web indices. Here, we used high‐throughput amplicon sequencing to investigate the effects of tillage (conventional vs. reduced) and organic matter addition (low vs. high) on nematode communities and food web indices in 10 European long‐term field experiments and we assessed the relationship between nematode communities and soil parameters. We found that nematode communities were more strongly affected by tillage than by organic matter addition. Compared to conventional tillage, reduced tillage increased nematode diversity (23% higher Shannon diversity index), nematode community stability (12% higher MI), structure (24% higher SI), and the fungal decomposition channel (59% higher CI), and also the number of herbivorous nematodes (70% higher). Total and labile organic carbon, available K and microbial parameters explained nematode community structure. Our findings show that nematode communities are sensitive indicators of soil quality and that molecular profiling of nematode communities has the potential to reveal the effects of soil management on soil quality

Optimal flexibility for conformational transitions in macromolecules

Conformational transitions in macromolecular complexes often involve the reorientation of lever-like structures. Using a simple theoretical model, we show that the rate of such transitions is drastically enhanced if the lever is bendable, e.g. at a localized "hinge''. Surprisingly, the transition is fastest with an intermediate flexibility of the hinge. In this intermediate regime, the transition rate is also least sensitive to the amount of "cargo'' attached to the lever arm, which could be exploited by molecular motors. To explain this effect, we generalize the Kramers-Langer theory for multi-dimensional barrier crossing to configuration dependent mobility matrices.Comment: 4 pages, 4 figure

Recent Studies of the Cosmic-Ray Latitude Effect at High Altitudes

With an improved Geiger counter telescope, having an angular aperture of about ±15° from its axis, a series of balloon flights was made in August and September, 1947, at seven stations extending from San Antonio, Texas, to Saskatoon, Canada. The axis of the telescope in all cases was oriented in a vertical direction. All sets of equipment were compared with a standard to reduce all results to a common basis. The standard sets, in turn, were compared with an accurately constructed telescope which had been used to make an absolute determination of cosmic-ray intensity at the vertical in Pasadena. Two flights were made from each of the seven stations. The agreement between flights made within a few hours of each other at a given station is very good. Results from two flights made at a given station several days apart are not in general as consistent. Likewise, no monotonic increase of the radiation with increase of latitude was observed. Evidence is presented for rather large fluctuations at high altitudes of the lower energy components of cosmic rays. Some of the reasons for these fluctuations are discussed

Cosmic-ray effects from solar flares and magnetic storms

Cosmic-ray data taken during the period of a solar flare and the magnetic storm that followed 26.5 hours later during July, 1946, are reported. The results following the flare agree with those of other investigators and, in addition, serve to establish the fact that the start of the cosmic-ray effect and the visual part of the solar flare were simultaneous. It is pointed out that increases of cosmic rays during solar flares suggest a mode of origin of the rays. The lack of effect of most solar flares on cosmic-ray intensity is noted and differences in intensity of the flares given as a possible reason. A high altitude balloon flight with an electroscope during the magnetic storm gave results in agreement with the current-sheet hypothesis of such storms but a serious objection to this hypothesis is given

The latitude effect for cosmic-ray showers

Cosmic-ray observations have been taken with Geiger counters on a voyage from San Francisco to Colombo via Japan and return via Australia. The apparatus used possesses some interesting features and is described at length. The latitude effect for vertical coincidences is found to be 14.5 percent in the region of the Dutch East Indies and 10 percent in the Pacific Ocean. The showers show a much smaller variation with latitude, only about 6 percent being found in the region of the East Indies. This result is interpreted as meaning that the latitude sensitive part of the radiation is not as efficient at producing showers as the nonlatitude sensitive radiation. Qualitatively at least, such behavior is consistent with the hypothesis that the latitude sensitive radiation is due to incoming electrons

Modified high speed Geiger counter circuit

Although the speed of the circuit designed by Neher(1) is quite satisfactory, it suffers from the disadvantages of requiring insulation for the cylinder and shielding if two or more Geiger counters are used to count coincidences. Also, the capacity of the cylinder for large counters introduces a longer reaction time. With the circuit to be described the cylinder of the counter is grounded

Effect of anisotropy and destructuration on behavior of Haarajoki test embankment

This paper investigates the influence of anisotropy and destructuration on the behavior of Haarajoki test embankment, which was built by the Finnish National Road Administration as a noise barrier in 1997 on a soft clay deposit. Half of the embankment is constructed on an area improved with prefabricated vertical drains, while the other half is constructed on the natural deposit without any ground improvement. The construction and consolidation of the embankment is analyzed with the finite-element method using three different constitutive models to represent the soft clay. Two recently proposed constitutive models, namely S-CLAY1 which accounts for initial and plastic strain induced anisotropy, and its extension, called S-CLAY1S which accounts, additionally, for interparticle bonding and degradation of bonds, were used in the analysis. For comparison, the problem is also analyzed with the isotropic modified cam clay model. The results of the numerical analyses are compared with the field measurements. The simulations reveal the influence that anisotropy and destructuration have on the behavior of an embankment on soft clay