Time minimal control of batch reactors

Abstract In this article we consider a control system modelling a batch reactor in which three species X

Electron transport through multilevel quantum dot

Quantum transport properties through some multilevel quantum dots sandwiched between two metallic contacts are investigated by the use of Green's function technique. Here we do parametric calculations, based on the tight-binding model, to study the transport properties through such bridge systems. The electron transport properties are significantly influenced by (a) number of quantized energy levels in the dots, (b) dot-to-electrode coupling strength, (c) location of the equilibrium Fermi energy $E_F$ and (d) surface disorder. In the limit of weak-coupling, the conductance ($g$) shows sharp resonant peaks associated with the quantized energy levels in the dots, while, they get substantial broadening in the strong-coupling limit. The behavior of the electron transfer through these systems becomes much more clearly visible from our study of current-voltage ($I$-$V$) characteristics. In this context we also describe the noise power of current fluctuations ($S$) and determine the Fano factor ($F$) which provides an important information about the electron correlation among the charge carriers. Finally, we explore a novel transport phenomenon by studying the surface disorder effect in which the current amplitude increases with the increase of the surface disorder strength in the strong disorder regime, while, the amplitude decreases in the limit of weak disorder. Such an anomalous behavior is completely opposite to that of bulk disordered system where the current amplitude always decreases with the disorder strength. It is also observed that the current amplitude strongly depends on the system size which reveals the finite quantum size effect.Comment: 12 pages, 7 figure

Synchrony and exertion during dance independently raise pain threshold and encourage social bonding

Group dancing is a ubiquitous human activity that involves exertive synchronized movement to music. It is hypothesized to play a role in social bonding, potentially via the release of endorphins, which are analgesic and rewardinducing, and have been implicated in primate social bonding. We used a 2 2 experimental design to examine effects of exertion and synchrony on bonding. Both demonstrated significant independent positive effects on pain threshold (a proxy for endorphin activation) and in-group bonding. This suggests that dance which involves both exertive and synchronized movement may be an effective group bonding activity

Association of Depressive Symptoms with Recurrent Falls: A Cross-Sectional Elderly Population Based Study and a Systematic Review

Background: Screening of depressive symptoms is recommended in recurrent fallers. Compared to the 30-item and 15-item Geriatric Depression Scales (GDS), the 4-item GDS is easier to administer and quicker to perform. The association between abnormal 4-item GDS score and recurrent falls has not yet been examined. In addition, while depressive symptoms-related gait instability is well known, the association with recurrent falls has been few studied. Objective: 1) To examine the association between abnormal 4-item GDS score and recurrent falls in community-dwelling older adults using original data from health examination centers (HEC) of French health insurance of Lyon, and 2) to perform a systematic review of studies that examined the association of depressive symptoms with recurrent falls among older adults. Methods: Firstly, based on a cross-sectional design, 2,594 community-dwellers (mean age 72.1 +/- 5.4years; 49.8% women) were recruited in HEC of Lyon, France. The 4-item GDS score (abnormal if score >= 1) and recurrent falls (i.e., 2 or more falls in the past year) were used as main outcomes. Secondly, a systematic English and French Medline literature search was conducted on May 28, 2012 with no limit of date using the following Medical Subject Heading (MeSH) terms "Aged OR aged, 80 and over", "Accidental falls", "Depressive disorder" and "Reccurence". The search also included the reference lists of the retrieved articles. Results: A total of 19.0% (n=494) participants were recurrent fillers in the cross-sectional study. Abnormal 4-item GDS score was more prevalent among recurrent fallers compared to non-recurrent fallers (44.7% versus 25.0%, with P<0.001), and was significantly associated with recurrent falls (Odd ratio (OR)=1.82 with P<0.001 for full model; OR=1.86 with P<0.001 for stepwise backward model). In addition to the current study, the systematic review found only four other studies on this topic, three of them examining the association of depressive symptoms with recurrent falls using 30-item or 15-item GDS. All studies showed a significant association of depressive symptoms with recurrent falls. Conclusions: The current cross-sectional study shows an association between abnormal 4-item GDS score and recurrent falls. This association of depressive symptoms with recurrent falls was confirmed by the systematic review. Based on these results, we suggest that recurrent falls risk assessment should involve a systematic screening of depressive symptoms using the 4-item GDS

Mobile Geriatric Team Advice: Effect on Length of Hospital Stay in Older Adults

International audienc

Translated from Itogi Nauki i Tekhniki, Seriya Sovremennaya Matematika i Ee Prilozheniya

Preliminaries Consider the local SR-geometry (U, D, g), where U is a neighborhood of 0 ∈ R 3 , D is a Martinet-type distribution, which can be taken in the normal form D = Ker ω, ω = dz − y 2 2 dx, and g is a C ω metric on D, which can be written (see Expanding F 1 and F 2 in Taylor series according to the previous weights and identifying at the order p two elements whose Taylor series are the same at the order p, we obtain the following normal forms of order −1 and 0: • Normal form of order −1: (flat case); • Normal form of order 0: 2 dx 2 + (1 + βx + γy) 2 dy 2 , α, β, γ ∈ R. 1.1. Geodesics equations. The energy minimization problem equivalent to the SR-problem is the following optimal control problem: from Pontryagin's maximum principle [9], minimizing solutions are solutions of the following equations: where H ν is the pseudo-Hamiltonian where ν is a constant normalized to 0 or 1/2. A solution of the previous equations is called an extremal; when ν = 1/2 (resp. ν = 0), the solutions are called normal (resp. abnormal), and their projections onto the state space are called the geodesics. They can be easily computed

The gas temperature in flaring disks around pre-main sequence stars

A model is presented which calculates the gas temperature and chemistry in the surface layers of flaring circumstellar disks using a code developed for photon-dominated regions. Special attention is given to the influence of dust settling. It is found that the gas temperature exceeds the dust temperature by up to several hundreds of Kelvins in the part of the disk that is optically thin to ultraviolet radiation, indicating that the common assumption that Tgas=Tdust is not valid throughout the disk. In the optically thick part, gas and dust are strongly coupled and the gas temperature equals the dust temperature. Dust settling has little effect on the chemistry in the disk, but increases the amount of hot gas deeper in the disk. The effects of the higher gas temperature on several emission lines arising in the surface layer are examined. The higher gas temperatures increase the intensities of molecular and fine-structure lines by up to an order of magnitude, and can also have an important effect on the line shapes.Comment: 14 pages, 10 figures, accepted for publication in A&