4,148 research outputs found
Micropulsations in the electric field near the plasmapause, observed by ISEE-1
The occurrence of micropulsations near and inside the plasmapause was surveyed. The observed pulsations, classified as Pc3 and Pi2, are discussed. In addition one single event of Pc1 was observed. The frequencies in the Pc3 and Pi2 bands, the amplitude ranges, and the direction of rotation for the electric field vector are reported
Impact of inter-correlated initial binary parameters on double black hole and neutron star mergers
The distributions of the initial main-sequence binary parameters are one of
the key ingredients in obtaining evolutionary predictions for compact binary
(BH-BH / BH-NS / NS-NS) merger rates. Until now, such calculations were done
under the assumption that initial binary parameter distributions were
independent. Here, we implement empirically derived inter-correlated
distributions of initial binary parameters primary mass (M1), mass ratio (q),
orbital period (P), and eccentricity (e). Unexpectedly, the introduction of
inter-correlated initial binary parameters leads to only a small decrease in
the predicted merger rates by a factor of 2 3 relative to the previously
used non-correlated initial distributions. The formation of compact object
mergers in the isolated classical binary evolution favors initial binaries with
stars of comparable masses (q = 0.5 1) at intermediate orbital periods (log
P (days) = 2 4). New distributions slightly shift the mass ratios towards
smaller values with respect to the previously used flat q distribution, which
is the dominant effect decreasing the rates. New orbital periods only
negligibly increase the number of progenitors. Additionally, we discuss the
uncertainty of merger rate predictions associated with possible variations of
the massive-star initial mass function (IMF). We argue that evolutionary
calculations should be normalized to a star formation rate (SFR) that is
obtained from the observed amount of UV light at wavelength 1500{\AA} (SFR
indicator). In this case, contrary to recent reports, the uncertainty of the
IMF does not affect the rates by more than a factor of 2. Any change to the IMF
slope for massive stars requires a change of SFR in a way that counteracts the
impact of IMF variations on the merger rates. In contrast, we suggest that the
uncertainty in cosmic SFR at low metallicity can be a significant factor at
play.Comment: accepted for publication in A&
Could Raphael’s School of Athens Contain Hidden Geometry?
In this article we argue that Raphael has hidden a geometric shape called a vesica piscis in his fresco The School of Athens (1510-1511). The vesica piscis, and several findings which can be interpreted as suggesting the presence of a vesica piscis in the fresco, are presented. Several of these suggestions relate to the vesica piscis drawn in the construction of an equilateral triangle in the first proposition of Euclid’s Elements. Based on findings in the fresco, we suggest that the vesica piscis should be interpreted in light of a philosophical and theological controversy which took place in Italy in the decades around 1500, between the Catholic Church and philosophers at the University of Padua
Neutrino masses from discrete gauge symmetries
We investigate a model with an extra gauge symmetry in the Standard
Model. We assume that only the scalars and the leptons carry non-zero charge.
The symmetry gives a structure to the mass matrix for the neutrinos. With two
extra Higgs singlets and two extra singlet right-handed neutrinos we can build
a model that fits the requirements of the MSW-solution of the Solar neutrino
problem. With a third singlet right-handed neutrino it is also possible to have
a 10 eV neutrino, a dark matter candidate.Comment: SNUTP 92-105, Late
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Digital Divide of Perceptions, Usage, and Purchase Items in Japanese E-Payment Adoption
The idea of a “digital divide” is a common issue in less developed countries but is also found in developed countries. We surveyed 151 Japanese to examine the effect of digital divide characteristics such as regional variations, age, and gender on the perception and behavior surrounding e-payments.
We find that regional difference affects Japanese perceptions, especially ease of use and trust, but not use. Also, older people are more like to use e-payment in terms of weekly frequency and amount of money spent than younger consumers. Japanese males, in general, have higher average scores in ease of use, importance of incentives, and usage than females. Moreover, males are more likely to purchase electronics, books, groceries, and services using e-payments
Technology requirements for post-1985 communications satellites
The technical and functional requirements for commercial communication satellites are discussed. The need for providing quality service at an acceptable cost is emphasized. Specialized services are postulated in a needs model which forecasts future demands. This needs model is based upon 322 separately identified needs for long distance communication. It is shown that the 1985 demand for satellite communication service for a domestic region such as the United States, and surrounding sea and air lanes, may require on the order of 100,000 MHz of bandwith. This level of demand can be met by means of the presently allocated bandwidths and developing some key technologies. Suggested improvements include: (1) improving antennas so that high speed switching will be possible; (2) development of solid state transponders for 12 GHz and possibly higher frequencies; (3) development of switched or steered beam antennas with 10 db or higher gain for aircraft; and (4) continued development of improved video channel compression techniques and hardware
An Empirical Investigation of Pull Requests in Partially Distributed BizDevOps Teams
In globally distributed projects, virtual teams are often partially
dispersed. One common setup occurs when several members from one company work
with a large outsourcing vendor based in another country. Further, the
introduction of the popular BizDevOps concept has increased the necessity to
cooperate across departments and reduce the age-old disconnection between the
business strategy and technical development. Establishing a good collaboration
in partially distributed BizDevOps teams requires extensive collaboration and
communication techniques. Nowadays, a common approach is to rely on
collaboration through pull requests and frequent communication on Slack. To
investigate barriers for pull requests in distributed teams, we examined an
organization located in Scandinavia where cross-functional BizDevOps teams
collaborated with off-site team members in India. Data were collected by
conducting 14 interviews, observing 23 entire days with the team, and observing
37 meetings. We found that the pull-request approach worked very well locally
but not across sites. We found barriers such as domain complexity, different
agile processes (timeboxed vs. flow-based development), and employee turnover.
Using an intellectual capital lens on our findings, we discuss barriers and
positive and negative effects on the success of the pull-request approach
Technology requirements for communication satellites in the 1980's
The key technology requirements are defined for meeting the forecasted demands for communication satellite services in the 1985 to 1995 time frame. Evaluation is made of needs for services and technical and functional requirements for providing services. The future growth capabilities of the terrestrial telephone network, cable television, and satellite networks are forecasted. The impact of spacecraft technology and booster performance and costs upon communication satellite costs are analyzed. Systems analysis techniques are used to determine functional requirements and the sensitivities of technology improvements for reducing the costs of meeting requirements. Recommended development plans and funding levels are presented, as well as the possible cost saving for communications satellites in the post 1985 era
The Engagement Model of Person-Environment Interaction
This article focuses on growth-promoting aspects in the environment, and the authors propose a strength-based, dynamic model of person-environment interaction. The authors begin by briefly discussing the typical recognition of contextual variables in models that rely on the concept of person-environment fit. This is followed by a review of recent approaches to incorporating positive environmental factors in conceptualizations of human functioning. These approaches lead to an alternative model of person-environment interaction in which the engagement construct (i.e., the quality of a person-environment relationship determined by the extent to which negotiation, participation, and evaluation processes occur during the interaction) replaces the static notion of fit. Finally, the authors outline recommendations for overcoming environmental neglect in research, practice, and training
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