3,095 research outputs found
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
2D Spectroscopy of Candidate Polar-Ring Galaxies: I. The Pair of Galaxies UGC 5600/09
Observations of the pair of galaxies VV 330 with the SCORPIO multimode
instrument on the 6-m Special Astrophysical Observatory telescope are
presented. Large-scale velocity fields of the ionized gas in H-alfa and
brightness distributions in continuum and H-alfa have been constructed for both
galaxies with the help of a scanning Fabry Perot interferometer. Long-slit
spectroscopy is used to study the stellar kinematics. Analysis of the data
obtained has revealed a complex structure in each of the pair components. Three
kinematic subsystems have been identified in UGC 5600: a stellar disk, an inner
gas ring turned with respect to the disk through ~80degrees, and an outer gas
disk. The stellar and outer gas disks are noncoplanar. Possible scenarios for
the formation of the observed multicomponent kinematic galactic structure are
considered, including the case where the large-scale velocity field of the gas
is represented by the kinematic model of a disk with a warp. The velocity field
in the second galaxy of the pair, UGC 5609, is more regular. A joint analysis
of the data on the photometric structure and the velocity field has shown that
this is probably a late-type spiral galaxy whose shape is distorted by the
gravitational interaction, possibly, with UGC 5600.Comment: 18 pages, 6 figure
Electron-Positron Pair Production in Space- or Time-Dependent Electric Fields
Treating the production of electron and positron pairs by a strong electric
field from the vacuum as a quantum tunneling process we derive, in
semiclassical approximation, a general expression for the pair production rate
in a -dependent electric field pointing in the -direction. We also
allow for a smoothly varying magnetic field parallel to . The result is
applied to a confined field for , a
semi-confined field for , and a linearly increasing
field . The boundary effects of the confined fields on
pair-production rates are exhibited. A simple variable change in all formulas
leads to results for electric fields depending on time rather than space.
In addition, we discuss tunneling processes in which empty atomic bound
states are spontaneously filled by negative-energy electrons from the vacuum
under positron emission. In particular, we calculate the rate at which the
atomic levels of a bare nucleus of finite size and large
are filled by spontaneous pair creation.Comment: 33 pages and 9 figures. to appear in Phys. Rev.
Casimir Energy of a Spherical Shell
The Casimir energy for a conducting spherical shell of radius is computed
using a direct mode summation approach. An essential ingredient is the
implementation of a recently proposed method based on Cauchy's theorem for an
evaluation of the eigenfrequencies of the system. It is shown, however, that
this earlier calculation uses an improper set of modes to describe the waves
exterior to the sphere. Upon making the necessary corrections and taking care
to ensure that no mathematically ill-defined expressions occur, the technique
is shown to leave numerical results unaltered while avoiding a longstanding
criticism raised against earlier calculations of the Casimir energy.Comment: LaTeX, 14 pages, 1 figur
Vacuum polarization for neutral particles in 2+1 dimensions
In 2+1 dimensions there exists a duality between a charged Dirac particle
coupled minimally to a background vector potential and a neutral one coupled
nonminimally to a background electromagnetic field strength. A constant uniform
background electric current induces in the vacuum of the neutral particle a
fermion current which is proportional to the background one. A background
electromagnetic plane wave induces no current in the vacuum. For constant but
nonuniform background electric charge, known results for charged particles can
be translated to give the induced fermion number. Some new examples with
infinite background electric charge are presented. The induced spin and total
angular momentum are also discussed.Comment: REVTeX, 7 pages, no figur
On the existence of Killing vector fields
In covariant metric theories of coupled gravity-matter systems the necessary
and sufficient conditions ensuring the existence of a Killing vector field are
investigated. It is shown that the symmetries of initial data sets are
preserved by the evolution of hyperbolic systems.Comment: 9 pages, no figure, to appear in Class. Quant. Gra
Electron-positron pair production in the Aharonov-Bohm potential
In the framework of QED we evaluate the cross section for electron-positron
pair production by a single photon in the presence of the external
Aharonov-Bohm potential in first order of perturbation theory. We analyse
energy, angular and polarization distributions at different energy regimes:
near the threshold and at high photon energies.Comment: LaTeX file, 13 page
Molecular characterisation of congenital myasthenic syndromes in Southern Brazil
Objective To perform genetic testing of patients with congenital myasthenic syndromes (CMS) from the Southern Brazilian state of Parana. Patients and methods Twenty-five CMS patients from 18 independent families were included in the study. Known CMS genes were sequenced and restriction digest for the mutation RAPSN p.N88K was performed in all patients. Results We identified recessive mutations of CHRNE in ten families, mutations in DOK7 in three families and mutations in COLQ, CHRNA1 and CHRNB1 in one family each. The mutation CHRNE c. 70insG was found in six families. We have repeatedly identified this mutation in patients from Spain and Portugal and haplotype studies indicate that CHRNE c. 70insG derives from a common ancestor. Conclusions Recessive mutations in CHRNE are the major cause of CMS in Southern Brazil with a common mutation introduced by Hispanic settlers. The second most common cause is mutations in DOK7. The minimum prevalence of CMS in Parana is 0.18/100 000
Molecular characterisation of congenital myasthenic syndromes in Southern Brazil
Objective To perform genetic testing of patients with congenital myasthenic syndromes (CMS) from the Southern Brazilian state of Parana. Patients and methods Twenty-five CMS patients from 18 independent families were included in the study. Known CMS genes were sequenced and restriction digest for the mutation RAPSN p.N88K was performed in all patients. Results We identified recessive mutations of CHRNE in ten families, mutations in DOK7 in three families and mutations in COLQ, CHRNA1 and CHRNB1 in one family each. The mutation CHRNE c. 70insG was found in six families. We have repeatedly identified this mutation in patients from Spain and Portugal and haplotype studies indicate that CHRNE c. 70insG derives from a common ancestor. Conclusions Recessive mutations in CHRNE are the major cause of CMS in Southern Brazil with a common mutation introduced by Hispanic settlers. The second most common cause is mutations in DOK7. The minimum prevalence of CMS in Parana is 0.18/100 000
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