full-FORCE: A Target-Based Method for Training Recurrent Networks

Trained recurrent networks are powerful tools for modeling dynamic neural computations. We present a target-based method for modifying the full connectivity matrix of a recurrent network to train it to perform tasks involving temporally complex input/output transformations. The method introduces a second network during training to provide suitable "target" dynamics useful for performing the task. Because it exploits the full recurrent connectivity, the method produces networks that perform tasks with fewer neurons and greater noise robustness than traditional least-squares (FORCE) approaches. In addition, we show how introducing additional input signals into the target-generating network, which act as task hints, greatly extends the range of tasks that can be learned and provides control over the complexity and nature of the dynamics of the trained, task-performing network.Comment: 20 pages, 8 figure

Production Hierarchies in Sweden

I study the internal organization of firms using occupation data on workers in Swedish manufacturing firms. Firms with more layers are larger in size, in value added, and they pay higher wages. Firms are hierarchal in that lower layers have more workers and lower mean wage than higher layers. Adding layers is associated with increases in mean firm size/value added and decreases in mean firm wages (at pre-existing layers). The reverse holds for removing layers. This result also holds for layer by layer mean size and wages for a majority of pre-existing layers

Effect of natural convection on oscillating flow in a pipe with cryogenic temperature difference across the ends

The effect of natural convection on the oscillatory flow in an open-ended pipe driven by a timewise sinusoidally varying pressure at one end and subjected to an ambient-to-cryogenic temperature difference across the ends, is numerically studied. Conjugate effects arising out of the interaction of oscillatory flow with heat conduction in the pipe wall are taken into account by considering a finite thickness wall with an insulated exterior surface. Two cases, namely, one with natural convection acting downwards and the other, with natural convection acting upwards, are considered. The full set of compressible flow equations with axissymmetry are solved using a pressure correction algorithm. Parametric studies are conducted with frequencies in the range 5–15 Hz for an end-to-end temperature difference of 200 and 50 K. Results are obtained for the variation of velocity, temperature, Nusselt number and the phase relationship between mass flow rate and temperature. It is found that the Rayleigh number has a minimal effect on the time averaged Nusselt number and phase angle. However, it does influence the local variation of velocity and Nusselt number over one cycle. The natural convection and pressure amplitude have influence on the energy flow through the gas and solid

CFD analysis of high frequency miniature pulse tube refrigerators for space applications with thermal non-equilibrium model

High frequency, miniature, pulse tube cryocoolers are extensively used in space applications because of their simplicity. Parametric studies of inertance type pulse tube cooler are performed with different length-to-diameter ratios of the pulse tube with the help of the FLUENT® package. The local thermal non-equilibrium of the gas and the matrix is taken into account for the modeling of porous zones, in addition to the wall thickness of the components. Dynamic characteristics and the actual mechanism of energy transfer in pulse are examined with the help of the pulse tube wall time constant. The heat interaction between pulse tube wall and the oscillating gas, leading to surface heat pumping, is quantified. The axial heat conduction is found to reduce the performance of the pulse tube refrigerator. The thermal non-equilibrium predicts a higher cold heat exchanger temperature compared to thermal equilibrium. The pressure drop through the porous medium has a strong non-linear effect due to the dominating influence of Forchheimer term over that of the linear Darcy term at high operating frequencies. The phase angle relationships among the pressure, temperature and the mass flow rate in the porous zones are also important in determining the performance of pulse tube refrigerator

Shafranov's virial theorem and magnetic plasma confinement

Shafranov's virial theorem implies that nontrivial magnetohydrodynamical equilibrium configurations must be supported by externally supplied currents. Here we extend the virial theorem to field theory, where it relates to Derrick's scaling argument on soliton stability. We then employ virial arguments to investigate a realistic field theory model of a two-component plasma, and conclude that stable localized solitons can exist in the bulk of a finite density plasma. These solitons entail a nontrivial electric field which implies that purely magnetohydrodynamical arguments are insufficient for describing stable, nontrivial structures within the bulk of a plasma.Comment: 9 pages no figure

RELEASE: A High-level Paradigm for Reliable Large-scale Server Software

Erlang is a functional language with a much-emulated model for building reliable distributed systems. This paper outlines the RELEASE project, and describes the progress in the first six months. The project aim is to scale the Erlang’s radical concurrency-oriented programming paradigm to build reliable general-purpose software, such as server-based systems, on massively parallel machines. Currently Erlang has inherently scalable computation and reliability models, but in practice scalability is constrained by aspects of the language and virtual machine. We are working at three levels to address these challenges: evolving the Erlang virtual machine so that it can work effectively on large scale multicore systems; evolving the language to Scalable Distributed (SD) Erlang; developing a scalable Erlang infrastructure to integrate multiple, heterogeneous clusters. We are also developing state of the art tools that allow programmers to understand the behaviour of massively parallel SD Erlang programs. We will demonstrate the effectiveness of the RELEASE approach using demonstrators and two large case studies on a Blue Gene

Proximity-induced ferromagnetism and chemical reactivity in few-layer VSe2 heterostructures

Among transition-metal dichalcogenides, mono and few-layers thick VSe2 has gained much recent attention following claims of intrinsic room-temperature ferromagnetism in this system, which have nonetheless proved controversial. Here, we address the magnetic and chemical properties of Fe/VSe2 heterostructure by combining element sensitive x-ray absorption spectroscopy and photoemission spectroscopy. Our x-ray magnetic circular dichroism results confirm recent findings that both native mono/few-layer and bulk VSe2 do not show intrinsic ferromagnetic ordering. Nonetheless, we find that ferromagnetism can be induced, even at room temperature, after coupling with a Fe thin film layer, with antiparallel alignment of the moment on the V with respect to Fe. We further consider the chemical reactivity at the Fe/VSe2 interface and its relation with interfacial magnetic coupling

Risk factors of ischemic stroke and subsequent outcome in hemodialysis patients

Background and purpose: End stage renal disease (ESRD) requiring hemodialysis (HD) carries up to a 10-fold greater risk of stroke than normal renal function. Knowledge concerning risk factors and management strategies derived from the general population may not be applicable to those with ESRD. We studied a large ESRD population to identify risk factors and outcomes for stroke. Methods: All adult patients receiving HD for ESRD from 01/01/2007 to 31/12/2012 were extracted from the electronic patient record. Variables associated with stroke were identified by survival analysis; demographic, clinical, imaging and dialysis related variables were assessed and case-fatality determined. Follow-up was until 31/12/2013. Results: 1382 patients were identified (mean age 60.5 years, 58.5% male). The prevalence of AF was 21.2% and 59.4% were incident HD patients. 160 (11.6%) experienced a stroke during 3471 patient-years of follow-up (95% ischemic). Stroke incidence was 41.5/1000 patient-years in prevalent and 50.1/1000 patient-years in incident HD patients. Factors associated with stroke on regression analysis were prior stroke, diabetes and age at starting renal replacement therapy. AF was not significantly associated with stroke and warfarin did not affect stroke risk in warfarin treated patients. Fatality was 18.8% at 7, 26.9% at 28 and 56.3% 365 days after stroke.<p></p> Conclusions: Incidence of stroke is high in patients with ESRD on HD with high case-fatality. Incident HD patients had the highest stroke incidence. Many, but not all, important risk factors commonly associated with stroke in the general population were not associated with stroke in patients receiving HD

Effect of post harvest ripening on bioactive secondary metabolites and antioxidant activity in mango cv. Amrapali

Mango possesses many bioactive phytonutrients at ripe stage which boost our immune systemagainst many diseases. Post harvest ripening plays a major role in changes in those bioactivephytochemicals and their antioxidant activity. Hence, the present study was undertaken toassess the changes in bioactive phytonutrients and total antioxidant activity during ripeningof mango cv. Amrapali. The fruits were analyzed for total antioxidants, total phenols, totalflavonoids and total carotenoids from the day of harvest to its deterioration. Fruit peel andpulp color was measured with SPH850 spectrophotometer on the basis of the CIE LAB colorsystem (L*, a* and b*). The results revealed that total phenols (36.11 to 66.53mg GAE 100g-1),total flavonoids (14.33 to 34.67mg QE 100g-1), total carotenoids (2.23 to 11.47mg 100g-1) andtotal antioxidant (0.37 to 0.76 mmol Trolox 100g-1) activity increased gradually from day one toninth day after harvest and decreased slightly thereafter up to eleventh day of harvest excepttotal carotenoids, which remained constant. Strong correlations between total phenols (0.94),total flavonoids (0.86) and total carotenoids (0.97) with total antioxidant activity were noticed.Positive relationship between total carotenoids and L*, a*, b* values in mango peel and pulpduring ripening was also observed. It can be concluded that ripening affected the compositionof bioactive phytonutrients and their antioxidant activity in mango andmaximum nutraceuticalscontents were noticed from seven to nine days after harvest

Financial experts on the board: does it matter for the profitability and risk of the u.k. banking industry?

This paper explores the relation between board-level financial expertise, the profitability and the risk profile with panel data from the UK banking industry. The empirical findings document that collectively, financial experts have a positive influence on the performance outcomes of banks, they contribute to higher risks, especially in the case of large banks, while they improve the stock performance of the associated banks. Moreover, the results highlight that board-level qualified accountants have no statistical effect on that profitability, while such a positive link is established for the case of financial and banking professors, as well as for financial experts from other industries. Such findings imply that these two groups of professional financial experts may be easier adopted at group-level profits enhancement. Robustness checks confirm the results for all types of banking institutions, except those with a strong real-estate activity portfolio. Finally, certain commercial and/or policy implications of the results are reported.N/