276 research outputs found
Enhancing student learning and teaching experience through a cross-level collaboration: a reflection
Graph Annotations in Modeling Complex Network Topologies
The coarsest approximation of the structure of a complex network, such as the
Internet, is a simple undirected unweighted graph. This approximation, however,
loses too much detail. In reality, objects represented by vertices and edges in
such a graph possess some non-trivial internal structure that varies across and
differentiates among distinct types of links or nodes. In this work, we
abstract such additional information as network annotations. We introduce a
network topology modeling framework that treats annotations as an extended
correlation profile of a network. Assuming we have this profile measured for a
given network, we present an algorithm to rescale it in order to construct
networks of varying size that still reproduce the original measured annotation
profile.
Using this methodology, we accurately capture the network properties
essential for realistic simulations of network applications and protocols, or
any other simulations involving complex network topologies, including modeling
and simulation of network evolution. We apply our approach to the Autonomous
System (AS) topology of the Internet annotated with business relationships
between ASs. This topology captures the large-scale structure of the Internet.
In depth understanding of this structure and tools to model it are cornerstones
of research on future Internet architectures and designs. We find that our
techniques are able to accurately capture the structure of annotation
correlations within this topology, thus reproducing a number of its important
properties in synthetically-generated random graphs
Finding the right fit: Enhancing the academic-industry link in the sector for Nutrition undergraduates – a pilot study
Academic learning experience prepares students for professional life, enriches their scientific-evidence knowledge, whereas laboratory practicals upskill their experiences applying theory into “real world” scenarios. As most undergraduate programmes are not offering placement year, students rely heavily on their initiatives and networking to maximise their continuous professional development (CPD). This study evaluated the supporting mechanisms between academia and industry/ sector and examined staff and students’ perceptions of existing academia-industry collaborations. An online survey was designed to record perceptions of undergraduate’s nutrition students. This was followed by focus groups to establish students’ perceptions of the relevant professional organisations and their related experiences outside academia. Captured students’ feedback together with the nutrition teaching academics responses in individual semi-structured interviews have portrayed the current academic-industry links, the perceived challenges/barriers and probed sensible roadmap. Six themes uncovered the need for extra nutrition-related work experiences, while the students’ perceptions reflected their learning through course progression, awareness of external opportunities and underpinned that graduate readiness improved progressively with years spent in study. The Academics’ interviews recognized the limited academic-industry collaborations and underpinned many barriers faced; more “top-down” support was identified as a strategy to enhance external links. The study provides a clear lens into the present academic-industry links within the nutrition programmes and ascertained the perceived challenges experienced by students and academics. Collaborations and centralised university communications shall promote a better university experience. Equally, staff-student partnerships will facilitate a new approach to understand both staff and students’ perspectives and enhance learning experiences within the sector
On the contribution of density perturbations and gravitational waves to the lower order multipoles of the Cosmic Microwave Background Radiation
The important studies of Peebles, and Bond and Efstathiou have led to the
formula C_l = const/[l(l +1)] aimed at describing the lower order multipoles of
the CMBR temperature variations caused by density perturbations with the flat
spectrum. Clearly, this formula requires amendments, as it predicts an
infinitely large monopole C_0, and a dipole moment C_1 only 6/2 times larger
than the quadrupole C_2, both predictions in conflict with observations. We
restore the terms omitted in the course of the derivation of this formula, and
arrive at a new expression. According to the corrected formula, the monopole
moment is finite and small, while the dipole moment is sensitive to
short-wavelength perturbations, and numerically much larger than the
quadrupole, as one would expect on physical grounds. At the same time, the
function l(l +1)C_l deviates from a horizontal line and grows with l, for l
\geq 2. We show that the inclusion of the modulating (transfer) function
terminates the growth and forms the first peak, recently observed. We fit the
theoretical curves to the position and height of the first peak, as well as to
the observed dipole, varying three parameters: red-shift at decoupling,
red-shift at matter-radiation equality, and slope of the primordial spectrum.
It appears that there is always a deficit, as compared with the COBE
observations, at small multipoles, l \sim 10. We demonstrate that a reasonable
and theoretically expected amount of gravitational waves bridges this gap at
small multipoles, leaving the other fits as good as before. We show that the
observationally acceptable models permit somewhat `blue' primordial spectra.
This allows one to avoid the infra-red divergence of cosmological
perturbations, which is otherwise present.Comment: prints to 25 pages including 14 figures, several additional sentences
on interpretation, new references, to appear in Int. Journ. Mod. Physics
Optimal map of the modular structure of complex networks
Modular structure is pervasive in many complex networks of interactions
observed in natural, social and technological sciences. Its study sheds light
on the relation between the structure and function of complex systems.
Generally speaking, modules are islands of highly connected nodes separated by
a relatively small number of links. Every module can have contributions of
links from any node in the network. The challenge is to disentangle these
contributions to understand how the modular structure is built. The main
problem is that the analysis of a certain partition into modules involves, in
principle, as many data as number of modules times number of nodes. To confront
this challenge, here we first define the contribution matrix, the mathematical
object containing all the information about the partition of interest, and
after, we use a Truncated Singular Value Decomposition to extract the best
representation of this matrix in a plane. The analysis of this projection allow
us to scrutinize the skeleton of the modular structure, revealing the structure
of individual modules and their interrelations.Comment: 21 pages, 10 figure
More Than Simply “Letting Go”: Stakeholder Perspectives on Parental Roles in Health Care Transition
The transfer from pediatric to adult health care for youth with special health care needs (YSHCN) is a vulnerable period. Parents play a pivotal role in the transition process, however, little is known about the specific ways they may support YSHCN in negotiating the transition to adult services. A qualitative supplementary secondary data analysis was conducted to explore stakeholders’ perceptions about parents’ roles in health care transition. Thematic analysis was used to analyze individual and focus group interviews. Four themes were identified: 1) Parents are crucial; 2) Changing roles; 3) Interdependence rather than independence; 4) One of many transitions. These themes may serve as the basis for planning future intervention studies directed at parents of YSHCN
On the observational determination of squeezing in relic gravitational waves and primordial density perturbations
We develop a theory in which relic gravitational waves and primordial density
perturbations are generated by strong variable gravitational field of the early
Universe. The generating mechanism is the superadiabatic (parametric)
amplification of the zero-point quantum oscillations. The generated fields have
specific statistical properties of squeezed vacuum quantum states.
Macroscopically, squeezing manifests itself in a non-stationary character of
variances and correlation functions of the fields, the periodic structures of
the metric power spectra, and, as a consequence, in oscillatory behavior of the
higher order multipoles C_l of the cosmic microwave background anisotropy. We
start with the gravitational wave background and then apply the theory to
primordial density perturbations. We derive an analytical formula for the
positions of peaks and dips in the angular power spectrum l(l+1)C_l as a
function of l. This formula shows that the values of l at the peak positions
are ordered in the proportion 1:3:5:..., whereas at the dips they are ordered
as 1:2:3:.... We compare the derived positions with the actually observed
features, and find them to be in reasonably good agreement. It appears that the
observed structure is better described by our analytical formula based on the
(squeezed) metric perturbations associated with the primordial density
perturbations, rather than by the acoustic peaks reflecting the existence of
plasma sound waves at the last scattering surface. We formulate a forecast for
other features in the angular power spectrum, that may be detected by the
advanced observational missions, such as MAP and PLANCK. We tentatively
conclude that the observed structure is a macroscopic manifestation of
squeezing in the primordial metric perturbations.Comment: 34 pages, 3 figures; to appear in Phys. Rev. D66, 0435XX (2002);
includes Note Added in Proofs: "The latest CBI observations (T.J.Pearson et
al., astro-ph/0205388) have detected four peaks, at l ~ 550, 800, 1150, 1500,
and four dips, at l ~ 400, 700, 1050, 1400. These positions are in a very
good agreement with the theoretical formula (6.35) of the present paper. We
interpret this data as confirmation of our conclusion that it is gravity, and
not acoustics, that is responsible for the observed structure.
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