Rumination and autobiographical memory impairment in patients with schizophrenia.

Although patients with schizophrenia exhibit autobiographical memory impairment, which is considered to be a limiting factor in their daily life, the mechanisms underlying such impairment have been rarely studied. In the current study, we investigate whether rumination and, in particular, brooding, which is a form of maladaptive repetitive thinking, may be linked to the difficulty that patients with schizophrenia experience when attempting to access specific autobiographical memories. Our results indicate that patients reported less specific autobiographical memories compared to control participants. Patients also displayed a higher level of brooding and had more depressive symptoms. According to the CaR-FA-X model (Williams et al., 2007), depression and brooding were associated with memory specificity in control participants. In contrast, neither depression nor brooding was correlated with memory specificity in patients. These results suggest that depression and rumination may not be directly related to patients' difficulty to recall specific memories and that other factors, such as metacognitive deficits, must first be considered when seeking interventions aimed to improve autobiographical memory in patients with schizophrenia.

Spatially resolved observation of dipole-dipole interaction between Rydberg atoms.

We have observed resonant energy transfer between cold Rydberg atoms in spatially separated cylinders. Resonant dipole-dipole coupling excites the 49s atoms in one cylinder to the 49p state while the 41d atoms in the second cylinder are transferred down to the 42p state. We have measured the production of the 49p state as a function of separation of the cylinders (0-80 microm) and the interaction time (0-25 micros). In addition, we measured the width of the electric field resonances. A full many-body quantum calculation reproduces the main features of the experiments.

Asymmetric response in a line of optically driven metallic nanospheres.

We describe the dipole-dipole interactions between a linear array of optically driven silver metallic nanospheres (MNSs). These model calculations incorporate the full electric field generated by an oscillating dipole and predict several interesting effects due to the retardation of the field. The distribution of the power associated with MNSs along the array shows a strong variation on a scale smaller than the wavelength of the driving light. For a given geometry, there is a small range of frequencies where the relative power in the last MNS compared to the first dramatically changes, suggesting a simple device for wavelength discrimination in this frequency range. Moreover, small changes in the driving frequency can completely change the direction of the scattered light when only a single nanosphere is driven.

Nestmate recognition signals of the leaf-cutting ant Atta laevigata.

Behavioral tests with field colonies of Atta laevigata were performed in order to identify the source of the odors used in nestmate recognition. We tested the postpharyngeal (PPG) and mandibular glands (MG) as putative organs producing chemical signals for nestmate recognition. Chemical analyses of PPG were also undertaken. With a series of bioassays, we confirmed that nestmate recognition is based on cephalic odors and that these odors come mainly from the mandibular gland secretion. We show chemical evidence that odors from MG are dispersed all over the cuticle. Although odors from PPG elicited colony-specific behavioral responses, the types of behaviors they elicited differed from those of nestmate recognition of whole ants or MG extracts. PPG secretion was characterized by long-chain alkanes and methyl branched alkanes of low volatility, whereas MG contained volatile ketones and alcohols.

Subthreshold rectification in neostriatal spiny projection neurons.

Intracellular recordings from slice preparations were used to assess the subthreshold electrophysiological behavior of rat neostriatal projection neurons. Both current steps and ramp currents were used to estimate the current-voltage relationship (I-V plot). Inward rectification in the subthreshold range was a characteristic of most neurons. The amount of rectification varied greatly, and it was complex: membrane voltage trajectories in response to ramps were made up by almost piece-wise changes in the rate of voltage rise, suggesting that multiple conductances contribute to the subthreshold range. Inward current blockers such as tetrodotoxin (TTX) or Cd2+ decreased inward rectification, whereas outward current blockers such as tetraethylammonium (TEA) or 4-aminopyridine (4-AP) increased inward rectification. However, most inward rectification was due to TEA- and Cs(+)-sensitive conductances and not to TTX- or Cd(2+)-sensitive conductances. Cs(+)-sensitive conductances predominated at more negative membrane potentials, whereas 4-AP-sensitive conductances predominated at just +/- 10 mV below the firing threshold. In spite of a very slow activation, there was evidence for transient outward currents modulating the response, i.e., 4-AP-sensitivity, and voltage-sensitivity for firing frequency and threshold. TEA-sensitive conductances also contributed toward fixing the firing threshold. These results imply the contribution of various ion conductances on the shaping of the characteristic physiological firing recorded in vivo. Modulation of these responses by transmitters or peptides may help to understand neural processing in the neostriatum.

Chemical ecology of the palm weevilRhynchophorus palmarum (L.) (Coleoptera: Curculionidae): Attraction to host plants and to a male-produced aggregation pheromone.

Attraction to host plants by adultRhynchophorus palmarum (L.) palm weevils was studied in the field and in the laboratory. Chemical analysis revealed the presence of ethanol and ethyl-acetate in stems of coco palms and in pineapple fruits and of pentane, hexanal, and isopentanol in coco stems. In the olfactometer, the first two compounds and isoamyl-acetate were attractive to the insects and the last three compounds, although not attractive by themselves, increased attractiveness when mixed with the first two compounds. Mixtures of these compounds, in proportions similar to the one occurring in attractive plant tissue, were as attractive as natural coconut tissue. In the field, the chemical compounds, either presented alone or as a mixture, did not attract the weevil. Males produce an aggregation pheromone when smelling ethyl-acetate. Rhynchophorol, 2(E)-6-methyl-2-hepten-4-ol, the known active component of the aggregation pheromone, attracts weevils in the olfactometer and in the field only if plant tissue, ethyl-acetate, or the above-mentioned odor mix are present. We propose that a complex mix of ethanol, ethyl-acetate, pentane, hexanal, isolamyl-acetate, and/or isopentanol serve as a short-range orientation cue to fresh wounds on the plant and that additional host odors, attracting weevils from a distance, have still to be discovered. Rhynchophorol can be considered to be a Synergist, having an anemotactic action at a distance. We recommend the use of retention traps baited with rhynchophorol, ethyl-acetate, and sugar cane as an alternative control method for the pest.

Blisters over burn scars in a child.

We present the case of an 11-month-old baby with a burn that healed normally over a month, but subsequently developed successive crops of blisters over the scar. There were no changes in his general condition. Clinical, immunological, histological and ultrastructural studies provided a diagnosis of mechanical dermatitis produced by microtrauma. Electron microscopy studies revealed the sub-epidermal nature of the blisters and the presence of underlying fibrin deposits.

[Scabies vs. histiocytosis X: a possible diagnostic error]. / Escabiosis versus histiocitosis X: posible error diagnóstico.

Scabies is a relatively common disease among Spanish children. The classic papulovesicular type is not usually a diagnostic problem. Therefore, the nodular type, much less frequent, is unknown for a lot of specialists (except dermatologist), and even it is mistaken for Histiocytosis or Lymphoma. Authors present a female infant, 6 months old, with nodular skin lesions whose first diagnosis was X-Histiocytosis. Regarding the big difference between the two processes (in respect of prognosis and treatment), this chance should be excluded, among others, when X-Histiocytosis is suspected in a child with sole skin affectation.