Prejudicial search and backprop

Journal ArticleThis paper introduces the combination of backward error propagation and prejudicial search. Prejudicial search is a method, which like simulated annealing, guarantees convergence to a global minimum as time approaches infinity. Unlike simulated annealing, its application is more flexible because it can be combined with other search methods. This method is applied to the exclusive-or problem. When prejudicial search is combined with backward error propagation, the resulting sum of mean squared error at each time step is between 10 and 70 percent (depending on t h e cooling schedule) of the normal backward error propagation error

Generality Vs. speed of convergence in the cart-pole balancer

technical reportThis paper compares the speed of convergence to an optimal solution of four controllers for the problem of balancing a pole on a cart. We demonstrate that controllers whose design is tailored specifically to the cart-pole problem (i.e. less general) converge more rapidly to an optimal solution. However, the architectures and learning algorithms for those networks may not perform well for more general tasks. The four controllers, ordered from the least general to the most general, are the Perceptron, the Associative Search Element [1], Jordan's approach [3], and Prejudicial Search applied to the ASE architecture. Two of the above neural networks, the Perceptron and Prejudicial Search [2] are new methods for solving this problem. The perceptron is a simple two input neuron (summing unit) with 2 weights and a step function output. The Prejudicial Search is a method for biasing the search of possible solutions. It guarantees convergence, but allows the search to be biased by heuristics or information about the problem. In this paper, it is combined with the ASE architecture. However, the Prejudicial Search technique can be combined with any architecture and learning algorithm, extending their ability to handle a more general class of problems

Home country effects of offshoring. A critical survey on empirical literature.

The International fragmentation of production processes is of rising importance. One part of this fragmentation involves the relocation of a production process from a home- to a new host country. This literature survey deals with the effects of such relocations on the home country. First of all, we try to conceptualize the terms and definitions most frequently used in this context which are "outsourcing", "offshore outsourcing" and "offshoring". Despite the fact that there is little textual documentation dealing directly with the phenomena of offshoring and offshore outsourcing we try to give an overview of possible empirical literature to which one can regard to. Including FDI literature we try to cover empirical literature which can provide helpful insight on the effects of a relocation to foreign countries on the home country in connection with wages, skill upgrading, prices, profits, taxes and unions. (author's abstract)Series: Discussion Papers SFB International Tax Coordinatio

Avaliação de Cleruchoides noackae em Laboratório e Campo em Minas Gerais, Brasil.

Resumo

Impact of hydrogen on the high cycle fatigue behaviour of Inconel 718 in asymmetric push–pull mode at room temperature

AbstractThe influence of hydrogen on the high cycle fatigue (HCF) behaviour of Inconel 718 has been studied at room temperature in asymmetric push–pull mode using an ultrasonic HCF test rig. Fatigue tests have been carried out in gaseous hydrogen (GH2) and in Ar at a pressure of 30MPa. Oscillating stresses with amplitudes (σa) up to 450MPa and mean stresses (σm) up to 600MPa have been applied. For a given σa and σm, the lifetime in Ar is generally longer than in GH2, which is explained by a hydrogen-induced embrittlement of the material. For a constant σa of 218MPa, the lifetime in Ar and in GH2 is very similar for high σm, but the difference in lifetime increases as the mean stress decreases. An approach is presented to describe the number of cycles to failure Nf as a function of σa and σm.Microstructural analysis has been performed on the specimens tested at σa=218MPa and two values of σm (300MPa and 600MPa). SEM analyses of the fracture surfaces of these samples indicate embrittlement of the material when tested in hydrogen atmosphere

Efeito do armazenamento a baixa temperatura na viabilidade do ovo de Thaumastocoris peregrinus (Hemiptera, Thaumastocoridae).

Resumo

Influência da densidade de fêmeas no parasitismo de Cleruchoides noackae (Hymenoptera, Mymaridae) sobre ovos de Thaumastocoris peregrinus (Hemiptera, Thaumastocoridae).

Resumo

NIRS-Derived Tissue Oxygen Saturation and Hydrogen Ion Concentration Following Bed Rest

Long-term bed rest (BR), a model of spaceflight, results in a decrease in aerobic capacity and altered submaximal exercise responses. The strongest BR-induced effects on exercise appear to be centrally-mediated, but longer BR durations may result in peripheral adaptations (e.g., decreased mitochondrial and capillary density) which are likely to influence exercise responses. PURPOSE: To measure tissue oxygen saturation (SO2) and hydrogen ion concentration ([H+]) in the vastus lateralis (VL) using near infrared spectroscopy (NIRS) during cycle ergometry before and after . 30 d of BR. METHODS: Eight subjects performed a graded exercise test on a cycle ergometer to volitional fatigue 7 d before (pre-BR) and at the end or 1 day after BR (post-BR). NIRS spectra were collected from a sensor adhered to the skin overlying the VL. Oxygen consumption (VO2) was measured by open circuit spirometry. Blood volume (BV) was measured before and after BR using the carbon monoxide rebreathing technique. Changes in pre- and post-BR SO2 and [H+] data were compared using mixed model analyses. BV and peak exercise data were compared using paired t-tests. RESULTS: BV (pre-BR: 4.3+/-0.3, post-BR: 3.7+/-0.2 L, mean+/-SE, p=.01) and peak VO2 (pre-BR: 1.98+/-0.24, post-BR: 1.48 +/-0.21 L/min, p<.01) were reduced after BR. As expected, SO2 decreased with exercise before and after BR. However, SO2 was lower post compared with pre-BR throughout exercise, including at peak exercise (pre-BR: 50+/-3, post-BR: 43+/-4%, p=.01). After BR, [H+] was higher at the start of exercise and did not increase at the same rate as pre-BR. Peak [H+] was not different from pre to post-BR (pre-BR: 36+/-2; post-BR: 38+/-2 nmol/L). CONCLUSIONS: Lower SO2 during exercise suggests that oxygen extraction in the VL is higher after BR, perhaps due to lower circulating blood volume. The higher [H+] after BR suggests a greater reliance upon glycolysis during submaximal exercise, although [H+] at peak exercise was unchanged. Taken together, these data suggest that longer duration BR induces a number of changes that result in peripheral adaptations which contribute to cardiovascular and muscular deconditioning as measured by NIRS-derived SO2 and [H+] in the VL and may contribute to lower post-BR exercise tolerance. Supported by the National Space Biomedical Research Institute through NASA NCC 9-5

Time-to-Fatigue and Intramuscular pH Measured via NIRS During Handgrip Exercise in Trained and Sedentary Individuals

In exercising muscles force production and muscular endurance are impaired by a decrease in intramuscular pH. The effects of aerobic training (AT) on preventing acidosis and prolonging exercise time in muscles not specifically targeted by the training are unknown. Purpose: To compare interstitial pH, measured non-invasively with near infrared spectroscopy (NIRS), in the flexor digitorum profundus (FDP) during rhythmic handgrip exercise in sedentary subjects and those who participate in AT activities that target the lower body. Methods: Maximal isometric force (MIF) was measured on three separate days in AT (n=5) and sedentary (n=8) subjects using a handgrip dynamometer (HGD). Isometric muscular endurance (IME) was measured during five trials, each separated by at least 48 hrs. For each IME trial subjects rhythmically squeezed (4 sec at 40% of MVC) and relaxed (2 sec) to fatigue or failure to reach the target force in three consecutive contractions or four non-consecutive contractions. Interstitial pH was derived from spectra collected using a NIRS sensor adhered to the skin over the FDP. The first four IME trials served to familiarize subjects with the protocol; the fifth trial was used for analysis. NIRS-derived pH was averaged in 30 sec increments. Between group differences in MIF and exercise time were tested using paired t-tests. A repeated measures ANOVA was used to analyze effects of AT and exercise time on pH. Results: MIF was not different between groups (mean SD; aerobic=415.6 95.4 N vs. sedentary =505.1 107.4 N). Time to fatigue was greater in the AT than in the sedentary group (mean SD: 611 173 sec vs. 377 162 sec, p<0.05). pH was not different between groups at any time point. Average pH decreased (p<0.05) in both groups from rest (pH=7.4) through 90 sec of exercise (pH=6.9), but did not decrease further throughout the remainder of exercise. Conclusion: Although between group differences in pH were not detected, differences during the onset of exercise may exist with a more frequent sampling. AT individuals appear to better tolerate decreased interstitial pH and are able to continue submaximal muscular work, possibly due to psychological familiarization to muscular fatigue and/or systemic physiological benefits