478 research outputs found
DecidArch: Playing Cards as Software Architects
Teaching software architecture is a challenge because of the difficulty to expose students to actual meaningful design situations. Games can provide a useful illustration of the design decision making process, and teach students the power of team interaction for making sound decisions. We introduce a game –DecidArch– developed to achieve three learning objectives: 1) create awareness about the rationale involved in design decision making, 2) enable appreciation of the reasoning behind candidate design decisions proposed by others, and 3) create awareness about interdependencies between design decisions. The game has been played by 22 groups with a total of 83 players, all of them students of the VU software architecture course. We present some of the lessons learned, both from our observation and through participant survey. We conclude that the game well supports our three learning objectives, and we identify several improvement points for future game editions
Generally Covariant Actions for Multiple D-branes
We develop a formalism that allows us to write actions for multiple D-branes
with manifest general covariance. While the matrix coordinates of the D-branes
have a complicated transformation law under coordinate transformations, we find
that these may be promoted to (redundant) matrix fields on the transverse space
with a simple covariant transformation law. Using these fields, we define a
covariant distribution function (a matrix generalization of the delta function
which describes the location of a single brane). The final actions take the
form of an integral over the curved space of a scalar single-trace action built
from the covariant matrix fields, tensors involving the metric, and the
covariant distribution function. For diagonal matrices, the integral localizes
to the positions of the individual branes, giving N copies of the single-brane
action.Comment: 34 pages, LaTeX. v2: comments and refs adde
D0-branes in Black Hole Attractors
Configurations of N probe D0-branes in a Calabi-Yau black hole are studied. A
large degeneracy of near-horizon bound states are found which can be described
as lowest Landau levels tiling the horizon of the black hole. These states
preserve some of the enhanced supersymmetry of the near-horizon AdS_2xS^2xCY
attractor geometry, but not of the full asymptotically flat solution.
Supersymmetric non-abelian configurations are constructed which, via the Myers
effect, develop charges associated with higher-dimensional branes wrapping CY
cycles. An SU(1,1|2) superconformal quantum mechanics describing D0-branes in
the attractor geometry is explicitly constructed.Comment: 27 page
Amoxicillin pharmacokinetics in preterm infants with gestational ages of less than 32 weeks
The multiple-dose pharmacokinetics of amoxicillin (AM [administered twice
daily in a 25-mg/kg of body weight intravenous dose]) in 17 preterm
infants (11 males; gestational age, 29 +/- 1.9 weeks; birth weight, 1,175
+/- 278 g) were evaluated on day 3 of life. Blood samples were collected
from an arterial catheter at 0, 0.5, 1, 2, 4, 8, and 12 h after the
intravenous dose. A high-performance liquid chromatography method was used
to determine AM concentrations in serum. AM pharmacokinetics followed a
one-compartment open model. The glomerular filtration rates of all
patients were simultaneously studied by means of the 24-h continuous
inulin infusion technique. The elimination half-life, apparent volume of
distribution, and total body clearance of AM (mean +/- standard deviation)
were 6.7 +/- 1.7 h, 584 +/- 173 ml, and 62.4 +/- 23.3 ml/h, respectively.
The mean (+/- standard deviation) AM peak and trough levels were 53.6 +/-
9.1 and 16.0 +/- 4.9 mg/liter, respectively. All infants had a serum
trough level above 5 mg/liter. The total body clearance and apparent
volume of distribution of AM and the clearance of inulin increased
significantly with increasing gestational age. The total bod
On the covariance of the Dirac-Born-Infeld-Myers action
A covariant version of the non-abelian Dirac-Born-Infeld-Myers action is
presented. The non-abelian degrees of freedom are incorporated by adjoining to
the (bosonic) worldvolume of the brane a number of anticommuting fermionic
directions corresponding to boundary fermions in the string picture. The
proposed action treats these variables as classical but can be given a matrix
interpretation if a suitable quantisation prescription is adopted. After
gauge-fixing and quantisation of the fermions, the action is shown to be in
agreement with the Myers action derived from T-duality. It is also shown that
the requirement of covariance in the above sense leads to a modified WZ term
which also agrees with the one proposed by Myers.Comment: 18 pages. Minor alterations to the text; references adde
Twisted K-Theory from Monodromies
RR fluxes representing different cohomology classes may correspond to the
same twisted K-theory class. We argue that such fluxes are related by
monodromies, generalizing and sometimes T-dual to the familiar monodromies of a
D7-brane. A generalized theta angle is also transformed, but changes by a
multiple of 2pi. As an application, NS5-brane monodromies modify the twisted
K-theory classification of fluxes. Furthermore, in the noncompact case K-theory
does not distinguish flux configurations in which dG is nontrivial in compactly
supported cohomology. Such fluxes are realized as the decay products of
unstable D-branes that wrapped nontrivial cycles. This is interpreted using the
E8 bundle formalism.Comment: 24 Pages, 6 eps figure
Do Arctic breeding geese track or overtake a green wave during spring migration?
Geese breeding in the Arctic have to do so in a short time-window while having sufficient body reserves. Hence, arrival time and body condition upon arrival largely influence breeding success. The green wave hypothesis posits that geese track a successively delayed spring flush of plant development on the way to their breeding sites. The green wave has been interpreted as representing either the onset of spring or the peak in nutrient biomass. However, geese tend to adopt a partial capital breeding strategy and might overtake the green wave to accomplish a timely arrival on the breeding site. To test the green wave hypothesis, we link the satellite-derived onset of spring and peak in nutrient biomass with the stopover schedule of individual Barnacle Geese. We find that geese track neither the onset of spring nor the peak in nutrient biomass. Rather, they arrive at the southernmost stopover site around the peak in nutrient biomass, and gradually overtake the green wave to match their arrival at the breeding site with the local onset of spring, thereby ensuring gosling benefit from the peak in nutrient biomass. Our approach for estimating plant development stages is critical in testing the migration strategies of migratory herbivores
To what extent does the securitisation of asylum seekers contribute to Australia’s failure to meet its relevant international human rights obligations?
BACKGROUND: Although it is well established that late-life depression is associated with both systemic low-graded inflammation and cognitive impairment, the relation between inflammation and cognition in depressed older persons is still equivocal. The objective of this study is to examine the association between plasma Neutrophil Gelatinase-Associated Lipocalin (NGAL) concentrations and cognitive functioning in late-life depression, including the potentially moderating role of sex. METHODS: A total of 369 depressed older persons (>/=60 years) from The Netherlands study of Depression in Older persons (NESDO) were included. Four cognitive domains, i.e. verbal memory, processing speed, interference control and attention were assessed with three cognitive tests (Stroop test, Wais Digit span test, and Rey's verbal learning test). Multiple linear regression analyses were applied with the four cognitive domains as dependent variables adjusted for confounders. RESULTS: The association between NGAL levels and specific cognitive domains were sex-specific. In women, higher NGAL levels were associated with impaired verbal memory and lower processing speed. In men, higher NGAL levels were associated with worse interference control. Higher NGAL levels were not associated with attention. No sex-specific associations of either high sensitivity C-reactive protein (hsCRP) or interleukin-6 (IL-6) with cognitive functioning were found. CONCLUSION: This study shows sex-specific association of NGAL with cognitive functioning in late-life depression
System integration of wind and solar power in Integrated Assessment Models: A cross-model evaluation of new approaches
Mitigation-Process Integrated Assessment Models (MP-IAMs) are used to analyze long-term transformation pathways of the energy system required to achieve stringent climate change mitigation targets. Due to their substantial temporal and spatial aggregation, IAMs cannot explicitly represent all detailed challenges of integrating the variable renewable energies (VRE) wind and solar in power systems, but rather rely on parameterized modeling approaches. In the ADVANCE project, six international modeling teams have developed new approaches to improve the representation of power sector dynamics and VRE integration in IAMs.
In this study, we qualitatively and quantitatively evaluate the last years' modeling progress and study the impact of VRE integration modeling on VRE deployment in IAM scenarios. For a comprehensive and transparent qualitative evaluation, we first develop a framework of 18 features of power sector dynamics and VRE integration. We then apply this framework to the newly-developed modeling approaches to derive a detailed map of strengths and limitations of the different approaches. For the quantitative evaluation, we compare the IAMs to the detailed hourly-resolution power sector model REMIX. We find that the new modeling approaches manage to represent a large number of features of the power sector, and the numerical results are in reasonable agreement with those derived from the detailed power sector model. Updating the power sector representation and the cost and resources of wind and solar substantially increased wind and solar shares across models: Under a carbon price of 30$/tCO2 in 2020 (increasing by 5% per year), the model-average cost-minimizing VRE share over the period 2050–2100 is 62% of electricity generation, 24%-points higher than with the old model version
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