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Airborne wind energy is a lightweight technology that allows power extraction from the wind using airborne devices such as kites and gliders, where the airfoil orientation can be dynamically controlled in order to maximize performance. The dynamical complexity of turbulent aerodynamics makes this optimization problem unapproachable by conventional methods such as classical control theory, which rely on accurate and tractable analytical models of the dynamical system at hand. Here we propose to attack this problem through reinforcement learning, a technique that—by repeated trial-and-error interactions with the environment—learns to associate observations with profitable actions without requiring prior knowledge of the system. We show that in a simulated environment reinforcement learning finds an efficient way to control a kite so that it can tow a vehicle for long distances. The algorithm we use is based on a small set of intuitive observations and its physically transparent interpretation allows to describe the approximately optimal strategy as a simple list of manoeuvring instructions. [ABSTRACT FROM AUTHOR]

The N13 component of somatosensory evoked potential (N13 SEP) represents the segmental response of dorsal horn neurons. In this neurophysiological study, we aimed to verify whether N13 SEP might reflect excitability changes of dorsal horn neurons during central sensitization. In 22 healthy participants, we investigated how central sensitization induced by application of topical capsaicin to the ulnar nerve territory of the hand dorsum modulated N13 SEP elicited by ulnar nerve stimulation. Using a double-blind placebo-controlled crossover design, we also tested whether pregabalin, an analgesic drug with proven efficacy on the dorsal horn, influenced capsaicin-induced N13 SEP modulation. Topical application of capsaicin produced an area of secondary mechanical hyperalgesia, a sign of central sensitization, and increased the N13 SEP amplitude but not the peripheral N9 nor the cortical N20-P25 amplitude. This increase in N13 SEP amplitude paralleled the mechanical hyperalgesia and persisted for 120 min. Pregabalin prevented the N13 SEP modulation associated with capsaicin-induced central sensitization, whereas capsaicin application still increased N13 SEP amplitude in the placebo treatment session. Our neurophysiological study showed that capsaicin application specifically modulates N13 SEP and that this modulation is prevented by pregabalin, thus suggesting that N13 SEP may reflect changes in dorsal horn excitability and represent a useful biomarker of central sensitization in human studies. [ABSTRACT FROM AUTHOR]

In this work, laser cutting of 6061-T6 aluminium alloy sheets is investigated using a multimode 150 W Nd:YAG pulsed laser, adopting N at 15 bar, with the aim to investigate the effect of process parameters on the kerf geometry and roughness. The study was divided in two steps: first, in order to determine the domain where a throughout cut is possible, cutting tests were performed at a fixed average power (150 W), changing the pulse duration and the cutting speed. Then, in order to assess the influence of the process parameters on kerf geometry and roughness, a second set of tests was carried out, at the same average power and pressure, changing the pulse duration, the scan speed and the beam travel direction. The tests were performed adopting a full factorial design 3 × 2 according to the DoE methodology. Analysis of variance (ANOVA) was used in order to determine which of the process parameters affects the kerf characteristic and how. Response surface method (RSM) and multiresponse optimisation (MRO) were adopted to optimise the process conditions. The various effects of the process parameters on the kerf geometry and quality have been analysed and discussed. Finally, it was found that the MRO is able to select a parameter set able to minimise the effects of the multimode energy distribution beam. [ABSTRACT FROM AUTHOR]

In the present study, fibre laser microdrilling of NIMONIC®263 sheet is investigated through an experimental testing campaign. Design of experiments (DOE) and analysis of variance (ANOVA) are applied with the aim to study the influence of the process parameters on the hole geometry and metallurgical properties. The results show that the laser allows drilling ~0.4-mm-thick NIMONIC®263 sheets with a trepanning speed up to 600 mm/min, obtaining good tolerance, low recast layer and absence of microcracks. [ABSTRACT FROM AUTHOR]

Laser bending is an innovative technology that uses a laser beam to bend metal sheets and/or components. It offers advantages such as lack of equipment, high flexibility, adaptability to different materials (including metal foams), and possibility of automation. Actually, the angle can be measured only after the laser-bending process. The acoustic emission (AE) technique offers a great potential for the 'on-time' evaluation of the bending angle: this technique is based on the detection of high-frequency acoustic signals emitted during the phenomena evolution deriving from the deformation and/or fracture of a component/structure. This paper presents an initial approach to understand the relationship between bending angle and the characteristics of the AE signals generated during the laser-material interaction. In this work, a diode laser is used to bend an AISI 304 stainless steel sheet: the laser parameters used and the bending angle obtained were correlated with each other. A useful dependence between laser bending and AE parameters was found. [ABSTRACT FROM AUTHOR]

In the present study, fine laser cutting of aluminium alloy 6061-T6 sheets, characterised by light reflection and heat conductivity, by means of a 150-W multimode lamp pumped Nd:YAG laser is investigated through an experimental testing campaign. Design of experiments (DoE) and analysis of variance (ANOVA) are adopted to study the influence of the process parameters on the kerf geometry and surface roughness. The results show that the laser allows cutting 1-mm-thick AA6061-T6 sheets with a cutting speed up to 700 mm/min, obtaining narrow kerfs (smaller than 200 μm), a fine taper angle (lower than 4°), a low dross height (about 40 μm) and a roughness average, Ra, around 4 μm. [ABSTRACT FROM AUTHOR]

We prove a lower semicontinuity result for polyconvex functionals of the Calculus of Variations along sequences of maps $$u:\Omega \subset \mathbb{R }^n\rightarrow \mathbb{R }^m$$ in $$W^{1,m}$$ , $$2\le m\le n$$ , bounded in $$W^{1,m-1}$$ and convergent in $$L^1$$ under mild technical conditions but without any extra coercivity assumption on the integrand. [ABSTRACT FROM AUTHOR]

Hepatitis C virus (HCV)-related cryoglobulinemia commonly causes disabling complications including peripheral neuropathy and neuropathic pain. In this prospective clinical, neurophysiological, and skin biopsy study we aimed at assessing clinical characteristics and risk factors of peripheral neuropathy and neuropathic pain in patients with HCV-related cryoglobulinemia. We enrolled 69 consecutive patients with HCV-related cryoglobulinemia. We diagnosed neuropathic pain with the DN4 (Neuropathic Pain Diagnostic) questionnaire, and rated the various neuropathic pains with the Neuropathic Pain Symptom Inventory (NPSI). All patients underwent a standard nerve conduction study to assess Aβ-fiber function, laser-evoked potentials to assess Aδ-fiber function, and skin biopsy to assess C-fiber terminals. Of the 69 patients studied, 47 had a peripheral neuropathy, and 29 had neuropathic pain. Patients with peripheral neuropathy were older than those without ( P < 0.0001). While peripheral neuropathy was significantly associated with the duration of HCV infection ( P < 0.01), it was unrelated to the duration of cryoglobulinemia and cryocrit ( P > 0.5). The severity of peripheral neuropathy significantly correlated with the duration of HCV infection ( P < 0.05). Laser-evoked potential amplitudes were significantly lower in patients with than in those without neuropathic pain ( P < 0.05). Conversely, no difference was found in nerve conduction study and skin biopsy findings ( P > 0.05). Our findings show that peripheral neuropathy is related to age and HCV infection, rather than to cryoglobulinemia, and neuropathic pain is associated with damage to nociceptive pathways as assessed with laser-evoked potentials; this might be useful for designing more effective clinical interventions for these common HCV related-cryoglobulinemia complications. [ABSTRACT FROM AUTHOR]

Patients with painful neuropathy frequently complain of pain in response to normally non-painful brushing, namely dynamic mechanical allodynia. Despite many animal studies suggesting that allodynia arises when the spontaneous firing in damaged nociceptive afferents sensitise second-order nociceptive neurons to Aβ-fibre input, no studies have sought to confirm this mechanism by investigating Aβ-fibre sparing in human patients with allodynia. In this study we compared data from Aβ-fibre-mediated nerve conduction studies and nociceptive-fibre-mediated laser-evoked potentials (LEPs) in 200 patients with distal symmetric polyneuropathy (114 with neuropathic pain, 86 without). Of the 114 patients with painful neuropathy studied, 44 suffered from allodynia. Whereas no statistical difference was found in nerve conduction study data between patients with and without allodynia, LEP amplitudes were larger in patients with allodynia than in those without ( P < 0.01 by Mann-Whitney U test). The lack of difference in NCS data between patients with and without allodynia suggest that this type of pain, rather than arising through second-order nociceptive neuron sensitization to Aβ-fibre input, might reflect a reduced mechanical threshold in sensitised intraepidermal nociceptive nerve terminals. [ABSTRACT FROM AUTHOR]

Aim of the work is to investigate the influence of the process parameters on the material removal rate (MRR) and on the surface roughness in engraving operation by using C45 carbon steel and a Q-Switched 20 W Yb:YAG fibre laser with the fundamental wavelength λ = 1070 nm. The examined parameters were: the pulse frequency, the beam speed, the distance between the linear patterns of two consecutive laser scans, the number of replications of the geometric pattern, and the scanning strategy (only horizontal lines or both horizontal and vertical lines). Experimental results have shown that the Yb:YAG fibre laser can be successfully used to machine C45 steel, obtaining three-dimensional engraved geometries with MRR and roughness strictly depending on the process parameters. [ABSTRACT FROM AUTHOR]

We aimed at assessing the prevalence of peripheral neuropathy in newly diagnosed, treatment-naïve patients with multiple myeloma. We enrolled 153 patients with multiple myeloma at initial diagnosis. All patients underwent neurological examination and nerve conduction study. Patients with suspected pure small fiber neuropathy underwent skin biopsy. Of the 153 patients included in this study, 7.2 % had a multiple myeloma-related neuropathy. All patients suffered from a distal symmetric sensory peripheral neuropathy, associated with age (P = 0.04). Our study on prevalence rate of multiple myeloma-related peripheral neuropathy might provide a basis for improving the clinical management of this condition. [ABSTRACT FROM AUTHOR]

An increase in the survival of neonates with antenatal diagnosis of malformations was achieved by the recent technical advances in neonatal intensive care units. The aim of this article is to describe the experience with neonatal arterial hypertension, in newborns with nephro-urological malformations, in a tertiary care referral Nursery, in a period of 4 years. Newborn medical records from the Nursery Annex to the Maternity of Hospital das Clinicas, School of Medicine, University of Sao Paulo, with the diagnosis of nephro-urological malformations and systemic arterial hypertension (SAH) at hospital discharge, in a period from January 1999 to January 2003, were retrospectively analysed. Among 10.278 live newborns in the studied period, 15 (0.15%) newborns were compatible with our inclusion criteria. Of these 15 newborns, 12 (80%) were male and three were premature (20%). In relation to aetiology, 13 (87%) showed urological malformations, 1 (6%) chronic renal insufficiency secondary to kidney dysplasia and one (6%) autosomal recessive polycystic kidney disease. SAH control was achieved with monotherapy in eight patients (53%), five patients (33%) needed an association of two drugs (calcium-channel blocker and angiotensin converting enzyme (ACE) inhibitor), one child used three types of antihypertensive drugs (calcium-channel blocker, ACE inhibitor and hydrochlorothiazide) for pressoric control and one child's blood pressure (BP) was controlled exclusively by peritoneal dialysis. The incidence of nephro-urological malformations in our service during the studied period was 0.89%. SAH incidence among these newborns was 19%. Our data reinforce previous studies pointing to the necessity to consider children with nephro-urological malformations as a risk group for SAH, who should have the BP evaluated since the neonatal period.Journal of Human Hypertension (2006) 20, 679–683. doi:10.1038/sj.jhh.1002051; published online 18 May 2006 [ABSTRACT FROM AUTHOR]

Strong-field laser-assisted radiation recombination is investigated: (a) to explore the control possibilities with two laser fields having commensurable frequencies and (b) to get some insight into the influence of the medium (a plasma) in which recombination occurs. It is found that by varying the relative phase of the two fields it is possible to control enhancement, broadening and symmetry properties of the recombination differential emitted power. In the case of an anisotropic two-temperature plasma, an interesting interplay is found between the shape of the laser-modified electron velocity distribution function and the shape of the emitted X-ray photon power spectrum. The novel features of strong laser-assisted radiative recombination are mostly restricted to the region of the process parameters corresponding to the physical situation when the characteristic electron velocities (translation, quiver and thermal) are comparable. A classical picture allows a fairly good understanding of the process. [ABSTRACT FROM AUTHOR]

We give a definition for Obstacle Problems with measure data and general obstacles. For such problems we prove existence and uniqueness of solutions and consistency with the classical theory of Variational Inequalities. Continuous dependence with respect to data is discussed. [ABSTRACT FROM AUTHOR]

Copyright of Il Nuovo Cimento: B is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento: B is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento: B is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A S-matrix formulation of charged-particle scattering in the presence of a laser radiation field is given. An clastic-scattering Born series is obtained, that is a rather straightforward generalization of the corresponding series without field. A diagrammatic representation is given to the terms of the series. The presence of the Bessel functions in different combinations in the developed formalism makes to treat exactly the terms higher than the first-order one rather difficult. To make the formalism manageable, various approximate expressions are derived for the limiting cases of small and large arguments of the Bessel functions, that correspond, respectively, to weak field and/or high frequencies and to strong fields and/or low frequencies. In these limits, the calculation of corrections to the first-order results is approximately as difficult as when there is no field. In the weak-field case, the scattering matrix elements (of any order in the scattering potential) are proportional to (A/ω), l being the net number of exchanged photons, A and ω, respectively, the amplitude and the frequency of the radiation field. Besides this, A/ω ≪ 1. Hence in this limit multiphoton exchanges result to bo quite unlikely. In the strong-field case, when A ≪ 1, each matrix element is proportional to (ω/A), N being the order in the scattering potential. Now the field amplitude appears at the denominators, thus contributions from high N are expected to be small. Contrary to the weak-field case, for a given N the analytic expressions of the matrix elements depend Si presenta una formulazione dello scattering da Potenziale in presenza di radiazione laser basata sulla matrice S. Si ottiene una serie di Born che è una diretta generalizzazione della corrispondente serie senza il campo. Ai termini della serie è associata una rappresentazione diagrammatica. La presenza di funzioni di Bessel in differenti combinazioni nel formalismo qui sviluppato rende piuttosto difficile trattare esattamente in termini di ordine superiore al primo. Per rendere il formalismo più maneggevole si derivano differenti espressioni approssimate per i casi limite di piccoli e grandi argomenti delle funzioni di Bessel, che corrispondono rispettivamente a deboli campi e/o alte frequenze, e a forti campi e/o basse frequenze. In questi limiti, il calcolo delle correzioni ai risultati del primo ordino presenta pressappoco lo stesso grado di difficoltà del caso di assenza di campo. Nel caso di debole campo gli elemonti di matrice di scattering (di qualsiasi ordine nel Potenziale di scattering) sono proporzionali a (A/ω), l essendo il numero netto di fotoni scambiati, A l'ampiezza e ω la frequenza del campo della radiazione. Inoltre, A/gw ≪ 1. Quindi in questo limite scambi di molti fotoni risultano altamente improbabili. Nel caso di forte campo, quando A/ω ≫ 1, ogni elemento di matrice è proporzionale a (ω/A), N essendo l'ordine nel Potenziale di scattering. Adesso l'ampiezza del campo appare al denominatore, così da rendere piccoli i contributi da termini con N alto. Contrariamente al caso di debole campo, per N assegnato le espressioni analitiche degli elementi di matrice dipendono poco dal numero dei fotoni scambiati. Quindi lo scambio di molti fotoni è ritenuto avere probabilità dello stesso ordine di grandezza di quello di pochi fotoni. Nel limite delie basse frequenze sotto particolari assunzioni si riottiene il risultato derivato precedentemente da Kroll e Watson con un approccio differente. Le ipotesi qui fatte consentono di associare al risultato un interessante quadro fisico. [ABSTRACT FROM AUTHOR]

The FAA has decided to install, operate, and maintain its own national microwave network called the Radio Communications Link (RCL) network. With this network and its capability to provide concentration points at any one of its microwave repeater locations, the FAA can substantially reduce Its leased line budget. This paper addresses the problem of determining the most cost-effective mix of point-to-point leased lines and ‘tail circuits’ to RCL concentrators for connecting communicating pairs of FAA facilities. The problem, formulated as an integer programming (IP) problem, is shown to be similar to the facility location problem. Also, like the facility problem, integral optimal solutions are frequently obtained. (The reason integral optimal solutions are frequently obtained for the facility location problem is not known.) Thus it is an example, more complex than the facility location problem, where such a phenomenon occurs. Also, the dimensionality of the problem precludes its being solved all in one piece. In this paper we formulate the problem, relate it to the facility location problem, and provide the partitioning and reduction techniques used to solve it in a reasonable amount of time. The partitioning and reduction techniques are independent of any particular formulation for this type of problem, and the solution methodology that would be applied to any subproblem. [ABSTRACT FROM AUTHOR]

We report on calculations of differential and total ionization cross-sections of hydrogen atoms irradiated by two radiation fields with different properties. One of the fields is of low intensity and relatively high frequency, the other is of low frequency and high intensity. In particular, we show that the inclusion of the multimode structure of the low-frequency laser field modifies considerably the shape of the angular distribution of the photoelectrons and the rates of ionization into the different channels characterized by the number of low-frequency photons exchanged. Further, we find that the average energy exchanged between the photoelectrons and the low-frequency radiation field is independent of the statistical properties of the low-frequency laser field. [ABSTRACT FROM AUTHOR]

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to assess the contribution of serotonergic (5-HT) mechanisms in the suppressant effect of amphetamine on punished responding, dose-effect curves of amphetamine on key-pecking behaviour of pigeons maintained by food presentation and punished by electric-shock were determined before and after pretreatment with methergoline, a potent and specific 5-HT receptor blocker in the central nervous system. A multiple fixed-interval 5 min, fixe-interval 5 min schedule of reinforcement in which every response, except the reinforced one, was punished in one of the two components (mult FI5 FI5-shock) was used. Effective doses of amphetamine decreased unpunished as well as punished FI response rates. However, the decreases in punished behaviour were more evident and dose-dependent. Methergoline markedly increased FI responding in the punished FI component but only slightly increased or decreased unpunished FI response rates. The most effective dose of methergoline for increasing punished responding was 0.56 mg/kg. Pretreatment with this dose of methergoline unmasked the facilitatory effects of amphetamine on unpunished responding, but did not antagonize its suppressant effect on punished responding. Therefore, although 5-HT seems to mediate punishment-induced response suppression and to inhibit the facilitatory effects of amphetamine on unpunished responding, it is not apparently involved in the suppressant effect of amphetamine on punished behaviour. [ABSTRACT FROM AUTHOR]

Dose-effect curves for amphetamine on keypecking behavior of pigeons maintained by two-component multiple schedules of shock postponement were determined. During the first experimental phase, the response-shock interval (RS) was held constant and the shock-shock interval (SS) varied. Under these conditions, shock rate was greater during the component with the shorter SS. However, response rates were comparable in both components. Also, the magnitude of the response rate increments caused by appropriate doses of amphetamine during both schedule components were similar. During the second experimental phase, the SS was held constant and the RS varied. As a consequence, baseline response rate was considerably lower in the component with the longer RS than in the short RS component. Shock presentations were also less frequent during the former than during the latter component, but the differences in shock rate between the components were comparable or smaller than those observed during the first experimental phase. Under these conditions, the effects of amphetamine in the two schedule components were markedly different, lower response rates being considerably more increased than higher rates. [ABSTRACT FROM AUTHOR]

We prove that local weak solutions of the orthotropic p-harmonic equation are locally Lipschitz, for every p≥2 and in every dimension. More generally, the result holds true for more degenerate equations with orthotropic structure, with right-hand sides in suitable Sobolev spaces. [ABSTRACT FROM AUTHOR]

Multiple sclerosis (MS) is a progressive disease of the CNS, characterized by the production of widespread lesions in the brain and spinal cord. Inflammatory demyelination has traditionally been seen as the main disease process in MS; however, axonal damage or loss is increasingly being documented to occur early in the disease. Cognitive deficits can occur independently of physical disability, which complicates their identification and recognition. More recently, cortical demyelination has been identified among possible causes of cognitive impairment in MS. Neuropsychological studies have consistently demonstrated that 40-65% of patients with MS experience cognitive dysfunction, particularly in recent memory, information processing speed, and sustained attention. Early detection of cognitive impairment is essential to enable therapeutic intervention to alleviate symptoms or prevent further cognitive decline, although how best to manage MS-related cognitive impairment is currently unclear. Treatment strategies for cognitive impairment in MS are still in their infancy. This article will summarize several pharmacological attempts to enhance cognitive performances in people with MS. [ABSTRACT FROM AUTHOR]