58 research outputs found
Non-localities in nucleon-nucleus potentials
Two causes of non-locality inherent in nucleon-nucleus scattering are
considered. They are the results of two-nucleon antisymmetry of the projectile
with each nucleon in the nucleus and the dynamic polarization potential
representation of channel coupling. For energies MeV, a
g-folding model of the optical potential is used to show the influence of the
knock-out process that is a result of the two-nucleon antisymmetry. To explore
the dynamic polarization potential caused by channel coupling, a multichannel
algebraic scattering model has been used for low-energy scattering.Comment: 12 pages, 11 figures, submitted to EPJ
Warum rauchen Schizophreniepatienten?
Zusammenfassung: Patienten mit schizophrenen Störungen zeigen eine erhöhte Prävalenz der Nikotinabhängigkeit. Diese Arbeit beleuchtet die Zusammenhänge zwischen Schizophrenie und Nikotinkonsum. Es gibt deutliche Hinweise dafür, dass wesentliche Bereiche kognitiver Funktionen bei Patienten mit schizophrenen Erkrankungen durch Nikotin verbessert werden, insbesondere Daueraufmerksamkeit, gerichtete Aufmerksamkeit, Arbeitsgedächtnis, Kurzzeitgedächtnis und Wiedergabe aus dem Gedächtnis. Auch konnten in einigen Studien mittels ereigniskorrelierten Potenzialen (P50-Paradigma) und der Präpulsinhibition des akustisch ausgelösten Schreckreflexes gezeigt werden, dass präattentive Maße der Informationsverarbeitung, die eine zentrale Rolle in der Schizophrenie spielen, durch Gabe von Nikotin verbessert werden können. Weiterhin kann Rauchen die durch antipsychotische Medikamente hervorgerufenen extrapyramidalen Nebenwirkungen verbessern, und es induziert das Zytochrom P4501A2, das auch an der Metabolisierung einiger Neuroleptika beteiligt ist. Zusammenfassend kann festgestellt werden, dass die Nikotinzufuhr bei Patienten mit schizophrenen Störungen eine Form der "Selbstmedikation" darstellen könnte, um Defizite im Bereich Aufmerksamkeit, Kognition und Informationsverarbeitung zu verbessern und um Nebenwirkungen von Antipsychotika zu reduzieren. Mögliche pharmakotherapeutische Ansätze zur Behandlung der gestörten Neurotransmission am nikotinergen Azetylcholinrezeptor werden diskutier
The pion-three-nucleon problem with two-cluster connected-kernel equations
It is found that the coupled piNNN-NNN system breaks into fragments in a
nontrivial way. Assuming the particles as distinguishable, there are indeed
four modes of fragmentation into two clusters, while in the standard three-body
problem there are three possible two-cluster partitions and conversely the
four-body problem has seven different possibilities. It is shown how to
formulate the pion-three-nucleon collision problem through the
integral-equation approach by taking into account the proper fragmentation of
the system. The final result does not depend on the assumption of separability
of the two-body t-matrices. Then, the quasiparticle method a' la
Grassberger-Sandhas is applied and effective two-cluster connected-kernel
equations are obtained. The corresponding bound-state problem is also
formulated, and the resulting homogeneous equation provides a new approach
which generalizes the commonly used techniques to describe the three-nucleon
bound-state problem, where the meson degrees of freedom are usually suppressed.Comment: 20 pages, REVTeX, with 3 COLOR figures (PostScript
Detailing the effects of polypharmacy in psychiatry: longitudinal study of 320 patients hospitalized for depression or schizophrenia
Current treatment standards in psychiatry are oriented towards polypharmacy, that is, patients receive combinations of several antidepressants, antipsychotics, mood stabilizers, anxiolytics, hypnotics, antihistamines, and anticholinergics, along with other somatic treatments. In tandem with the beneficial effects of psychopharmacological drug treatment, patients experience significant adverse reactions which appear to have become more frequent and more severe with the rise of ubiquitous polypharmacy. In this study, we aimed to assess today's acute inpatient treatment of depressive and schizophrenic disorders with focus on therapeutic strategies, medications, adverse side effects, time course of recovery, and efficacy of treatments. Of particular interest was the weighing of the benefits and drawbacks of polypharmacy regimens. We recruited a total of 320 patients hospitalized at three residential mental health treatment centers with a diagnosis of either schizophrenic (ICD-10: "F2x.x"; n = 94; "F2 patients") or depressive disorders (ICD-10: "F3x.x"; n = 226; "F3 patients"). The study protocol included (1) assessment of previous history by means of the SADS Syndrome Check List SSCL-16 (lifetime version); (2) repeated measurements over 5 weeks assessing the time course of improvement by the Hamilton Depression Scale HAM-D and the Positive and Negative Syndrome Scale PANSS, along with medications and adverse side effects through the Medication and Side Effects Inventory MEDIS; and (3) the collection of blood samples from which DNA and serum were extracted. Polypharmacy was by far the most common treatment regimen (85%) in this study. On average, patients received 4.50 ± 2.68 medications, consisting of 3.30 ± 1.84 psychotropic drugs, plus 0.79 ± 1.13 medications that alleviate adverse side effects, plus 0.41 ± 0.89 other somatic medications. The treating psychiatrists appeared to be the main determining factor in this context, while «previous history» and «severity at baseline» played a minor role, if at all. Adverse drug reactions were found to be an inherent component of polypharmacy and tended to have a 2-3 times higher incidence compared to monotherapy. Severe adverse reactions could not be attributed to a particular drug or drug combination. Rather, the empirical data suggested that severe side effects can be triggered by virtually all combinations of drugs, provided patients have a respective vulnerability. In terms of efficacy, there were no advantages of polypharmacy over monotherapy. The results of this study underlined the fact that polypharmacy regimens are not equally suited for every patient. Specifically, such regimens appeared to have a negative impact on treatment outcome and to obfuscate the "natural" time course of recovery through a multitude of interfering factors. Evidence clearly speaks against starting just every therapeutic intervention in psychiatry with a combination of psychopharmaceuticals. We think that it is time for psychiatry to reconsider its treatment strategies, which are far too one-sidedly fixated on psychopharmacology and pay far too little attention to alternative approaches, especially in mild cases where psychotherapy without concurrent medication should still be an option. Also, regular exercises and sports can definitely be an effective therapeutic means in a considerable number of cases. General practitioners (GPs) are particularly in demand here
Practical approximation scheme for the pion dynamics in the three-nucleon system
We discuss a working approximation scheme to a recently developed formulation
of the coupled piNNN-NNN problem. The approximation scheme is based on the
physical assumption that, at low energies, the 2N-subsystem dynamics in the
elastic channel is conveniently described by the usual 2N-potential approach,
while the explicit pion dynamics describes small, correction-type effects.
Using the standard separable-expansion method, we obtain a dynamical equation
of the Alt-Grassberger-Sandhas (AGS) type. This is an important result, because
the computational techniques used for solving the normal AGS equation can also
be used to describe the pion dynamics in the 3N system once the matrix
dimension is increased by one component. We have also shown that this
approximation scheme treats the conventional 3N problem once the pion degrees
of freedom are projected out. Then the 3N system is described with an extended
AGS-type equation where the spin-off of the pion dynamics (beyond the 2N
potential) is taken into account in additional contributions to the driving
term. These new terms are shown to reproduce the diagrams leading to modern
3N-force models. We also recover two sets of irreducible diagrams that are
commonly neglected in 3N-force discussions, and conclude that these sets should
be further investigated, because a claimed cancellation is questionable.Comment: 18 pages, including 5 figures, RevTeX, Eps
The pd <--> pi+ t reaction around the Delta resonance
The pd pi+ t process has been calculated in the energy region around the
Delta-resonance with elementary production/absorption mechanisms involving one
and two nucleons. The isobar degrees of freedom have been explicitly included
in the two-nucleon mechanism via pi-- and rho-exchange diagrams. No free
parameters have been employed in the analysis since all the parameters have
been fixed in previous studies on the simpler pp pi+ d process. The
treatment of the few-nucleon dynamics entailed a Faddeev-based calculation of
the reaction, with continuum calculations for the initial p-d state and
accurate solutions of the three-nucleon bound-state equation. The integral
cross-section was found to be quite sensitive to the NN interaction employed
while the angular dependence showed less sensitivity. Approximately a 4% effect
was found for the one-body mechanism, for the three-nucleon dynamics in the p-d
channel, and for the inclusion of a large, possibly converged, number of
three-body partial states, indicating that these different aspects are of
comparable importance in the calculation of the spin-averaged observables.Comment: 40 Pages, RevTex, plus 5 PostScript figure
Exploring the similarities and differences between medical assessments of competence and criminal responsibility
The medical assessments of criminal responsibility and competence to consent to treatment are performed, developed and debated in distinct domains. In this paper I try to connect these domains by exploring the similarities and differences between both assessments. In my view, in both assessments a decision-making process is evaluated in relation to the possible influence of a mental disorder on this process. I will argue that, in spite of the relevance of the differences, both practices could benefit from the recognition of this similarity. For cooperative research could be developed directed at elucidating exactly how various mental disturbances can affect decision-making processes
Inflammatory processes linked to major depression and schizophrenic disorders and the effects of polypharmacy in psychiatry: evidence from a longitudinal study of 279 patients under therapy
Over the past 2 decades, polypharmacy has become the de-facto standard of acute treatment in psychiatry where patients with psychiatric disorders receive a multiple medication regimen. There is growing evidence for a potential link between major psychiatric disorders and inflammatory processes. Combining these two aspects aims at avoiding polypharmacy attempts among patients with inflammatory activation through alternative treatment strategies. In this study, we addressed the following questions: (1) to what extent can polypharmacy be explained through the factors “diagnosis”, “previous history”, “severity at baseline”, “age”, “gender”, and “psychiatrist in charge”; (2) what are the differences between polypharmacy and monotherapy regarding efficacy and side effect profiles; and (3) what amount of between-patient variance is explainable by the natural antibody immunoglobulin M (IgM) within each diagnostic group. This naturalistic longitudinal study was comprised of 279 patients under therapy with a clinical diagnosis of depressive (ICD-10: “F3x.x”; n = 195) or schizophrenic disorders (ICD-10: “F2x.x”; n = 84). The study protocol included (1) assessment of previous history by the SADS Syndrome Check List SSCL-16 (lifetime version); (2) repeated measurements over 5 weeks assessing the time course of improvement by the Hamilton Depression Scale HAM-D and the Positive and Negative Syndrome Scale PANSS, along with medication and unwanted side effects through the Medication and Side Effects Inventory MEDIS; and (3) the collection of blood samples from which DNA and serum were extracted. The association between inflammatory response system and psychiatric disorders was detailed by fitting multi-layer Neural Net (NN) models to the observed data (“supervised learning”). The same approach was used to set up prediction models of side effects. Our data showed that polypharmacy was omnipresent. Yet the various polypharmacy regimens had no advantage over monotherapy: we even found slightly larger baseline score reductions under monotherapy, independent of primary diagnoses and for comparable baseline severities. Most patients experienced unwanted side effects. The close link between side effects and treatment regimen was revealed by a linear model in which the mere number of drugs explained a significant (p < 0.001) proportion of the observed variance. As to the inflammatory response system: For the F2 patients, our NN model identified a 22.5% subgroup exhibiting a significant correlation of r = 0.746 (p = 0.0004) between global schizophrenia scores and IgM levels, along with a correct prediction of response of 94.4%, thus explaining 55.7% of the observed between-patient variance. For the F3 patients, our NN model identified a 19.6% subgroup exhibiting a significant correlation of r = 0.644 (p = 0.00003) between global depression scores and IgM levels, along a correct prediction of response of 89.6%, thus explaining 41.4% of the observed between-patient variance. Polypharmacy is omnipresent in today’s acute treatment of psychiatric disorders. Given the large proportion of patients with unwanted side effects and the strong correlation between side effects and the number of drugs, polypharmacy approaches are not equally suited for every patient. In terms of efficacy, there are no advantages of polypharmacy over monotherapy. Most notably, our study appears to have cleared the way for the reliable identification of a subgroup of patients for whom the inflammatory response system is a promising target of therapeutic intervention
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