Research Shows the Cost Benefits of Resident Services on the Performance of Property Operations

In the past, anecdotal evidence has suggested that resident services in affordable family housing help reduce operational costs. This is the third study to support and validate that anecdotal evidence with concrete data. The study found that resident services reduce operational costs related to vacancy loss, bad debt and legal fees

Bounds on series-parallel slowdown

We use activity networks (task graphs) to model parallel programs and consider series-parallel extensions of these networks. Our motivation is two-fold: the benefits of series-parallel activity networks and the modelling of programming constructs, such as those imposed by current parallel computing environments. Series-parallelisation adds precedence constraints to an activity network, usually increasing its makespan (execution time). The slowdown ratio describes how additional constraints affect the makespan. We disprove an existing conjecture positing a bound of two on the slowdown when workload is not considered. Where workload is known, we conjecture that 4/3 slowdown is always achievable, and prove our conjecture for small networks using max-plus algebra. We analyse a polynomial-time algorithm showing that achieving 4/3 slowdown is in exp-APX. Finally, we discuss the implications of our results.Comment: 12 pages, 4 figure

Hybrid performance modelling of opportunistic networks

We demonstrate the modelling of opportunistic networks using the process algebra stochastic HYPE. Network traffic is modelled as continuous flows, contact between nodes in the network is modelled stochastically, and instantaneous decisions are modelled as discrete events. Our model describes a network of stationary video sensors with a mobile ferry which collects data from the sensors and delivers it to the base station. We consider different mobility models and different buffer sizes for the ferries. This case study illustrates the flexibility and expressive power of stochastic HYPE. We also discuss the software that enables us to describe stochastic HYPE models and simulate them.Comment: In Proceedings QAPL 2012, arXiv:1207.055

Transport through a double quantum dot with interdot repulsion

We study transport through a double quantum dot with interdot hopping $t$, intradot repulsion $U$ and interdot repulsion $U^{\prime}$, using the numerical renormalization group (NRG) method. At half-filling, the conductances in two-terminal series and four-terminal parallel configuration are calculated via two phase shifts for quasi-particles of double quantum dot connected to two noninteracting leads with hybridization strength $\Gamma$. For small values of $t/\Gamma$ and $U^{\prime}/U$, conductance in the two-terminal series configuration is suppressed to almost zero. In this region, plateau of conductance in the four-terminal parallel configuration appears and almost reaches a unitary limit value $4e^{2}/h$ of two conducting modes. For large values of $t/\Gamma$ or $U^{\prime}/U$, both conductances are suppressed to almost zero. The conductance in the two-terminal series configuration almost reaches a unitary limit value $2e^{2}/h$ only around cross-over regions of electron-configuration in double quantum dot. Through the behavior of the local charge and some thermodynamic quantities, we discuss the relation between transport and electron-configuration.Comment: To be published in "Journal of Physics: Condensed Matter

In the eye of the storm: preliminary evidence on the use of online learning diaries

The surprising lack of pressure and speed in the centre of the vortex of a storm are in stark contrast to the force and destruction often experienced at its periphery. Many spectators watching a developing storm will be caught between fear and a desire to escape. The metaphor of a storm has been applied here to the emotions experienced by many students enrolling in online learning courses. Not only do the requirements of studying online collide with personal and professional commitments, the experience of learning online (often in groups) results in many students feeling displaced, scared or out of control. Learning diaries, especially in an online environment, present students with an opportunity to reach the centre of the vortex, though this may not be as quiet and safe as we may have presumed. This paper reports on students’ reflections in their learning diaries as a prescriptive part of the Professional Certificate in Management offered by the Open University. The research focused on the unstructured learning diary entries of 12 students from one tutor group over an 18 day period of a short compulsory online course. This phenomenographic study used grounded theory as methodology to analyse and describe students’ use of their learning diaries. The research found ample evidence that online learning diaries provide students with a safe space to reflect on the vortex around them. Without a quiet and reflective centre, students may be overwhelmed by the wider forces impacting on them. Students’ postings provided rich descriptions of the vortex of studying online and the function of having a centre to which to withdraw. There is, however, also evidence that posting reflections in learning diaries can itself be a dislocating and uncomfortable experience for some learners, while others question its usefulness. The work provides practical and useful information for managers of online learning experiences, instructional designers and curriculum developer

HYPE with stochastic events

The process algebra HYPE was recently proposed as a fine-grained modelling approach for capturing the behaviour of hybrid systems. In the original proposal, each flow or influence affecting a variable is modelled separately and the overall behaviour of the system then emerges as the composition of these flows. The discrete behaviour of the system is captured by instantaneous actions which might be urgent, taking effect as soon as some activation condition is satisfied, or non-urgent meaning that they can tolerate some (unknown) delay before happening. In this paper we refine the notion of non-urgent actions, to make such actions governed by a probability distribution. As a consequence of this we now give HYPE a semantics in terms of Transition-Driven Stochastic Hybrid Automata, which are a subset of a general class of stochastic processes termed Piecewise Deterministic Markov Processes.Comment: In Proceedings QAPL 2011, arXiv:1107.074

Dynamics of capacitively coupled double quantum dots

We consider a double dot system of equivalent, capacitively coupled semiconducting quantum dots, each coupled to its own lead, in a regime where there are two electrons on the double dot. Employing the numerical renormalization group, we focus here on single-particle dynamics and the zero-bias conductance, considering in particular the rich range of behaviour arising as the interdot coupling is progressively increased through the strong coupling (SC) phase, from the spin-Kondo regime, across the SU(4) point to the charge-Kondo regime; and then towards and through the quantum phase transition to a charge-ordered (CO) phase. We first consider the two-self-energy description required to describe the broken symmetry CO phase, and implications thereof for the non-Fermi liquid nature of this phase. Numerical results for single-particle dynamics on all frequency scales are then considered, with particular emphasis on universality and scaling of low-energy dynamics throughout the SC phase. The role of symmetry breaking perturbations is also briefly discussed.Comment: 14 pages, 6 figure

Project Fear: how the negativity of the referendum campaign undermines democracy

The referendum debate is not living up to its democratic ideals. Both sides of the divide have focused heavily on negative, fear-based arguments to make their case, which prevent democratic engagement among the electorate. Charlotte Galpin shows how this negativity is inhibiting critical reflection and fostering cynicism. She also notes that the debate is non-inclusive, with an striking absence of minorities and female experts in the campaign

Boris Johnson is damaging Germany’s goodwill towards the UK

Boris Johnson is damaging Germany’s goodwill towards the UK, argues Charlotte Galpin. She writes that despite Germany’s long-standing respect for its British partners, the Federal Republic trades more with the EU27 than it does with the UK and it has a profound ideological commitment to European integration that is seldom appreciated in Britain