1,636 research outputs found
Comparative biochemical studies on the lipids of marine invertebrates, with special reference to the sterols
For a number of years the author and his collaborators have been engaged in a systematic comparative study of the fatty constituents of marine invertebrates. So far special attention has been devoted mainly to the unsaponifiable fractions of such fats, in particular to the sterols which they contain. Work on the phosphatide fractions of invertebrate fats and their saponifiable components is now in progress and will be discussed in a future publication
Computus und Computer: CHRONOS – ein Programm zur mathematischen und technischen Chronologie
The medieval determination of the Easter cycle has even today a topical evidence in chronology and calendariography, as the easier formula published by C. F. Gauss in 1800 was not accepted in chronology. To verify dates in past and future, both historians and calendariographs until now could only use tabular-compilation based on different systems. The CHRONOS program offers a chronologic/ calendariographic fundamentum by means of which you can answer all essential questions of l'art vérfier les dates and calendariography. CHRONOS includes a calendarÃan ranging from 4713 b.C. to 3268 a.C. as well as a computation of the changeable holidays of the years 293-2499 for the Julian and Gregorian calendar. Moreover it can determine the Jewish Passah holiday and the Jewish New Year's day. Especially interesting for the historians is the possibility to find out the computistic key-dates of a year, to convert the eras used in historiography, and to implement the medieval calendar of saints. In this connection the Mohammedian calendar is also offered in concordance with the Christian one. The Chronos program substitutes and surpasses the traditional chronological facilities of the historian
The muonic longitudinal shower profiles at production
In this paper the longitudinal profile of muon production along the shower
axis is studied. The characteristics of this distribution is investigated for
different primary masses, zenith angles, primary energies, and different high
energy hadronic models. It is found that the shape of this distribution
displays universal features similarly to what is known for the electromagnetic
profile. The relation between the muon production distribution and the
longitudinal electromagnetic evolution is also discussed
Antimicrobial Peptide Human Neutrophil Peptide 1 as a Potential Link Between Chronic Inflammation and Ductal Adenocarcinoma of the Pancreas
Objectives Defensins are antimicrobial peptides playing a role in innate immunity, in epithelial cell regeneration, and in carcinogenesis of inflammation-triggered malignancies. We analyzed this role in pancreatic ductal adenocarcinoma (PDAC) in the context of its association with chronic pancreatitis (CP). Methods Human tissue of healthy pancreas, CP, and PDAC was screened for defensins by immunohistochemistry. Defensin 1 (human neutrophil peptide 1 [HNP-1]) expression was validated using mass spectrometry and microarray analysis. Human neutrophil peptide 1 expression and influences of proinflammatory cytokines (tumor necrosis factor , interleukin 1, and interferon ) were studied in human pancreatic cancer cells (Colo 357, T3M4, PANC-1) and normal human pancreatic duct epithelial cells (HPDE). Results Accumulation of HNP-1 in malignant pancreatic ductal epithelia was seen. Spectrometry showed increased expression of HNP-1 in CP and even more in PDAC. At RNA level, no significant regulation was found. In cancer cells, HNP-1 expression was significantly higher than in HPDE. Proinflammatory cytokines significantly led to increased HNP-1 levels in culture supernatants and decreased levels in lysates of cancer cells. In HPDE cytokines significantly decreased HNP-1 levels. Conclusions Inflammatory regulation of HNP-1 in PDAC tissue and cells indicates that HNP-1 may be a link between chronic inflammation and malignant transformation in the pancreas
On the measurement of the proton-air cross section using longitudinal shower profiles
In this paper, we will discuss the prospects of deducing the proton-air cross
section from fluorescence telescope measurements of extensive air showers. As
it is not possible to observe the point of first interaction
directly, other observables closely linked to must be inferred from
the longitudinal profiles. This introduces a dependence on the models used to
describe the shower development. The most straightforward candidate for a good
correlation to is the depth of shower maximum . We
will discuss the sensitivity of an -based analysis on and quantify the systematic uncertainties arising from the model
dependence, parameters of the reconstruction method itself and a possible
non-proton contamination of the selected shower sample.Comment: 4 pages, Proceedings for ISVHECRI Weihei 200
REAS3: Monte Carlo simulations of radio emission from cosmic ray air showers using an "end-point" formalism
In recent years, the freely available Monte Carlo code REAS for modelling
radio emission from cosmic ray air showers has evolved to include the full
complexity of air shower physics. However, it turned out that in REAS2 and all
other time-domain models which calculate the radio emission by superposing the
radiation of the single air shower electrons and positrons, the calculation of
the emission contributions was not fully consistent. In this article, we
present a revised implementation in REAS3, which incorporates the missing radio
emission due to the variation of the number of charged particles during the air
shower evolution using an "end-point formalism". With the inclusion of these
emission contributions, the structure of the simulated radio pulses changes
from unipolar to bipolar, and the azimuthal emission pattern becomes nearly
symmetric. Remaining asymmetries can be explained by radio emission due to the
variation of the net charge excess in air showers, which is automatically taken
into account in the new implementation. REAS3 constitutes the first
self-consistent time-domain implementation based on single particle emission
taking the full complexity of air shower physics into account, and is freely
available for all interested users.Comment: 18 pages, 13 figures accepted by Astroparticle Physics (2010
Sensitivity of the correlation between the depth of shower maximum and the muon shower size to the cosmic ray composition
The composition of ultra-high energy cosmic rays is an important issue in
astroparticle physics research, and additional experimental results are
required for further progress. Here we investigate what can be learned from the
statistical correlation factor r between the depth of shower maximum and the
muon shower size, when these observables are measured simultaneously for a set
of air showers. The correlation factor r contains the lowest-order moment of a
two-dimensional distribution taking both observables into account, and it is
independent of systematic uncertainties of the absolute scales of the two
observables. We find that, assuming realistic measurement uncertainties, the
value of r can provide a measure of the spread of masses in the primary beam.
Particularly, one can differentiate between a well-mixed composition (i.e., a
beam that contains large fractions of both light and heavy primaries) and a
relatively pure composition (i.e., a beam that contains species all of a
similar mass). The number of events required for a statistically significant
differentiation is ~ 200. This differentiation, though diluted, is maintained
to a significant extent in the presence of uncertainties in the phenomenology
of high energy hadronic interactions. Testing whether the beam is pure or
well-mixed is well motivated by recent measurements of the depth of shower
maximum.Comment: Accepted for publication in Astroparticle Physics, LA-UR-12-2008
Electronics and Sensor Subsystem Design for Daedalus 2 on REXUS 29: An Autorotation Probe for Sub-Orbital Re-Entry
The Daedalus 2 mission aboard REXUS 29 is a technology demonstrator for an
alternative descent mechanism for very high altitude drops based on
auto-rotation. It consists of two probes that are ejected from a sounding
rocket at an altitude of about 80 km and decelerate to a soft landing using
only a passive rotor with pitch control. This type of autonomous, scientific
experiment poses great challenges upon the electronics subsystem, which include
mechanical stress, power system reliability, sensor redundancy, subsystem
communication, and development procedures. Based on the data gathered in
Daedalus 1 multiple new approaches were developed to fulfill these
requirements, such as redundant communication links, mechanical decoupling of
PCBs and fault-tolerant power source selection.Comment: 8 pages, 10 figure
Investigation of the effect of residual stresses in the subsurface on process forces for consecutive orthogonal cuts
The quality and surface integrity of machined parts is influenced by residual stresses in the subsurface resulting from cutting operations. These stress characteristics can not only affect functional properties such as fatigue life, but also the process forces during machining. Especially for orthogonal cutting as an appropriate experimental analogy setup for machining operations like milling, different undeformed chip thicknesses cause specific residual stress formations in the subsurface area. In this work, the process-related depth profile of the residual stress in AISI 4140 was investigated and correlated to the resulting cutting forces. Furthermore, an analysis of the microstructure of the cut material was performed, using additional characterization techniques such as electron backscatter diffraction and nanoindentation to account for subsurface alterations. On this basis, the influence of process-related stress profiles on the process forces for consecutive orthogonal cutting strategies is evaluated and compared to the results of a numerical model. The insights obtained provide a basis for future investigations on, e. g., empirical modeling of process forces including the influence of process-specific characteristics such as residual stress
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