Dynamical strategies for obstacle avoidance during Dictyostelium discoideum aggregation: a Multi-agent system model

Chemotaxis, the movement of an organism in response to chemical stimuli, is a typical feature of many microbiological systems. In particular, the social amoeba \textit{Disctyostelium discoideum} is widely used as a model organism, but it is not still clear how it behaves in heterogeneous environments. A few models focusing on mechanical features have already addressed the question; however, we suggest that phenomenological models focusing on the population dynamics may provide new meaningful data. Consequently, by means of a specific Multi-agent system model, we study the dynamical features emerging from complex social interactions among individuals belonging to amoeba colonies.\\ After defining an appropriate metric to quantitatively estimate the gathering process, we find that: a) obstacles play the role of local topological perturbation, as they alter the flux of chemical signals; b) physical obstacles (blocking the cellular motion and the chemical flux) and purely chemical obstacles (only interfering with chemical flux) elicit similar dynamical behaviors; c) a minimal program for robustly gathering simulated cells does not involve mechanisms for obstacle sensing and avoidance; d) fluctuations of the dynamics concur in preventing multiple stable clusters. Comparing those findings with previous results, we speculate about the fact that chemotactic cells can avoid obstacles by simply following the altered chemical gradient. Social interactions are sufficient to guarantee the aggregation of the whole colony past numerous obstacles

Double Resonance in Dalitz Plot of M(pLambda)-M(KLambda) in DISTO Data on p+p rightarrow p+Lambda+K+ at 2.85 GeV

The X(2265) resonance was previously observed in DISTO data of p+p rightarrow p+Lambda+K+ at 2.85 GeV on an attempt of searching for the kaonic nuclear state K-pp rightarrow p + Lambda. In the present paper we report an additional finding, namely, a double resonance type phenomena, not only with a peak at M(pLambda) = 2265 MeV/c2 but also a broad bump at M(K+ Lambda) ~ 1700 MeV/c2. This "double-resonance" zone is expressed as XY(2265, 1700). The latter bump may result from nearby nucleon resonances, typically N*(1710), as well as by attractive K - Lambda final-state interaction. We point out that this double resonance XY(2265, 1700) as seen in DISTO at 2.85 GeV cannot be populated kinematically in a HADES experiment at 3.5 GeV.Comment: 4 pages, 3 figures, HYP2015 conferenc

Monte Carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions: the fully polarized case

In this paper, we extend the study of Drell-Yan processes with antiproton beams already presented in a previous work. We consider the fully polarized $\bar{p}^\uparrow p^\uparrow \to \mu^+ \mu^- X$ process, because this is the simplest scenario for extracting the transverse spin distribution of quarks, or transversity, which is the missing piece to complete the knowledge of the nucleon spin structure at leading twist. We perform Monte Carlo simulations for transversely polarized antiproton and proton beams colliding at a center-of-mass energy of interest for the future HESR at GSI. The goal is to possibly establish feasibility conditions for an unambiguous extraction of the transversity from data on double spin asymmetries.Comment: Produced in RevTeX 4, 10 figures in .eps forma

The Complex Trauma Questionnaire (ComplexTQ). Development and preliminary psychometric properties of an instrument for measuring early relational trauma

Research on the etiology of adult psychopathology and its relationship with childhood trauma has focused primarily on specific forms of maltreatment. This study developed an instrument for the assessment of childhood and adolescence trauma that would aid in identifying the role of co-occurring childhood stressors and chronic adverse conditions. The Complex Trauma Questionnaire (ComplexTQ), in both clinician and self-report versions, is a measure for the assessment of multi-type maltreatment: physical, psychological, and sexual abuse; physical and emotional neglect as well as other traumatic experiences, such rejection, role reversal, witnessing domestic violence, separations, and losses. The four-point Likert scale allows to specifically indicate with which caregiver the traumatic experience has occurred. A total of 229 participants, a sample of 79 nonclinical and that of 150 high-risk and clinical participants, were assessed with the ComplexTQ clinician version applied to Adult Attachment Interview (AAI) transcripts.Initial analyses indicate acceptable inter-rater reliability. A good fit to a 6-factor model regarding the experience with the mother and to a 5-factor model with the experience with the father was obtained; the internal consistency of factors derived was good. Convergent validity was provided with the AAI scales. ComplexTQ factors discriminated normative from high-risk and clinical samples. The findings suggest a promising, reliable, and valid measurement of early relational trauma that is reported; furthermore, it is easy to complete and is useful for both research and clinical practice

Emerging criteria for the low-coherence cannot classify category

As suggested by Main et al., to respond to the need for an adaptation of the existing Adult Attachment Interview (AAI) coding system, especially regarding the application to nonnormative samples, this study presents additional criteria that characterize the low-coherence cannot classify (CC) category. Three AAIs were selected from a sample of parents of maltreated children. All transcripts indicated a very low coherence, with no evidence of contradictory insecure discourse strategies. Moreover, global category descriptors were identified, together with specific indices of discourse characteristics and features that highlight the breakdown in reasoning and discourse experienced by the speakers. The aim of the study is to illustrate new criteria to identify and rate a low-coherence CC profile toward the operationalization of this pervasively unintegrated state of mind. Through the definition of additional criteria for low-coherence CC category, our study helps the AAI and its coding system be more flexible and effective when dealing with clinical samples

The role of thalamo-frontocortical mechanisms in measures of spatial learning and memory

Human amnesia has been attributed to diencephalic lesions produced by Wernicke-Korsakoff syndrome, tumor, trauma and infarct. Rodent models of diencephalic amnesia suggest the involvement of three anatomic systems, namely the nuclei of the brainstem and diencephalon, the mammillary bodies, and the mediodorsal nucleus of the thalamus. In recent years our laboratory has investigated these systems. Only radiofrequency (RF) lesions of the thalamus involving lateral portions of the internal medullary lamina (L-IML) and including the mediodorsal nucleus (MDn) of the thalamus have disrupted measures of learning and memory in a manner that is qualitatively similar to that seen in human Korsakoff amnesics. The purpose of the experiments reported here was to further examine the neurologic basis of these deficits. The effects of RF lesions of the L-IML were compared to lesions restricted to two areas of prefrontal cortex (PFC) found to be denervated by the L-IML lesion, i.e. the shoulder of the medial wall (MW) and the cortex dorsal to the rhinal sulcus (RS). Memory was assessed with three tasks: the radial arm maze (RAM), spatial serial reversal (SSR), and spatial delayed nonmatching to sample (DNMTS) tasks. Also, Wheat Germ Agglutinate - Horseradish Peroxidase (WGA-HRP) analyses were done to verify the extent to which MDn projections to PFC were affected by these lesions. Rodents with lesions of the L-IML were impaired on all three tasks, performing significantly worse than the cortical groups on RAM and DNMTS. Although they committed more errors during initial learning of SSR, like MWs and RSs they exhibited a preserved capacity to perform this task, and demonstrated positive transfer. The PFC groups were impaired only on DNMTS, suggesting that neither of these areas alone can account for the full complement of deficits observed in animals with L-IML lesions. WGA-HRP analyses verified that neither prefrontal lesion interrupted pathways from the thalamus to the other prefrontal area, indicating that these lesions successfully destroyed most of the intended targets