Testing one-body density functionals on a solvable model

There are several physically motivated density matrix functionals in the literature, built from the knowledge of the natural orbitals and the occupation numbers of the one-body reduced density matrix. With the help of the equivalent phase-space formalism, we thoroughly test some of the most popular of those functionals on a completely solvable model.Comment: Latex, 16 pages, 4 figure

Enfermedad de Fournier. Nuestra casuística

Introducción: La enfermedad de Fournier es unagangrena de los tejidos blandos, localizada en lasregiones perineal o genital, causada por acción sinergísticade microorganismos aerobios y anaerobios,cuya evolución es potencialmente letal y deaparición relativamente frecuente en los servicios deCirugía General, en nuestro medio.Objetivos: En el presente trabajo se revisa datossobre el cuadro clínico, enfermedades concomitantes,sitio de origen, tratamiento y resultados.Pacientes y métodos: Estudio observacional,descriptivo y retrospectivo de 46 enfermos tratadosen la II Cátedra de Clínica Quirúrgica, Hospital deClínicas, FCM - UNA y el Departamento de Cirugíadel Hospital Nacional de Itauguá, en un periodo de10 años ( marzo 1995 a febrero 2005).Resultados: fueron varones 37 (80,4%) y 9 mujeres(19,6%). La edad promedio fue de 62 años (extremosentre 33 a 85 años). La etiología fue: abscesoanal 35 pacientes (76,2%), afecciones urológicas 10(21,7%) y pío dermitis 1(2,1%). Los síntomas máscomunes fueron fiebre y dolor (36 y 32 pacientes respectivamente).La enfermedad de base más frecuente fue la DiabetesMellitus (28 pacientes); otros fueron artritisreumatoide, Etilismo y TBC.El tratamiento quirúrgico consistió en desbridamientosamplios, en más de una oportunidad. Lacitostomía se realizó en 2 pacientes y colostomía enasa en 22 pacientes. La antibióticoterapia implementadafue cefotaxima o ciprofloxacina, acompañada demetronidazol.Ingresaron a UCI 18 pacientes, de los cuales fallecieron7 por shock séptico.El tiempo de hospitalización tuvo un promediode 45 días (rango de 4 a 201 días).Conclusión: El cuadro clínico permite el diagnósticofácil. El tratamiento debe ser agresivo, precoz,con resecciones amplias y reiteradas.Más de la mitad se originan en infecciones analesy la diabetes mellitus es la enfermedad condicionantemás frecuente

Temporal configuration and modality of components determine the performance of bumble bees during the learning of a multimodal signal

Across communicative systems, the ability of compound signals to enhance receiver's perception and decoding is a potent explanation for the evolution of complexity. In nature, complex signaling involves spatiotemporal variation in perception of signal components; yet, how the synchrony between components affects performance of the receiver is much less understood. In the coevolution of plants and pollinators, bees are a model for understanding how visual and chemical components of floral displays may interact to influence performance. Understanding whether the temporal dimension of signal components impacts performance is central for evaluating hypotheses about the facilitation of information processing and for predicting how particular trait combinations function in nature. Here, I evaluated the role of the temporal dimension by testing the performance of bumble bees under restrained conditions while learning a bimodal (olfactory and visual) stimulus. I trained bumble bees under six different stimuli varying in their internal synchrony and structure. I also evaluated the acquisition of the individual components. I show that the temporal configuration and the identity of the components impact their combined and separate acquisition. Performance was favored by partial asynchrony and the initial presentation of the visual component, leading to higher acquisition of the olfactory component. This indicates that compound stimuli resembling the partially synchronous presentation of a floral display favor performance in a pollinator, thus highlighting the time dimension as crucial for the enhancement. Moreover, this supports the hypothesis that the evolution of multimodal floral signals may have been favored by the asynchrony perceived by the receiver during free flight. © 2023. Published by The Company of Biologists Ltd.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

The flavonoid rutin protects the bumble bee Bombus impatiens against cognitive impairment by imidacloprid and fipronil

The ongoing decline of bee populations and its impact on food security demands integrating multiple strategies. Sublethal impairments associated with exposure to insecticides, affecting the individual and the colony levels, have led to insecticide moratoria and bans. However, legislation alone is not sufficient and remains a temporary solution to an evolving market of insecticides. Here, we asked whether bees can be prophylactically protected against sublethal cognitive effects of two major neurotoxic insecticides, imidacloprid and fipronil, with different mechanisms of action. We evaluated the protective effect of the prophylactic administration of the flavonoid rutin, a secondary plant metabolite, present in nectar and pollen, and known for its neuroprotective properties. Following controlled or ad libitum administration of rutin, foragers of the North American bumble bee Bombus impatiens received oral administration of the insecticides at sublethal realistic dosages. Learning acquisition, memory retention and decision speed were evaluated using olfactory absolute conditioning of the proboscis extension response. We show that the insecticides primarily impair acquisition but not retention or speed of the conditioned proboscis extension response. We further show that the administration of the flavonoid rutin successfully protects the bees against impairments produced by acute and chronic administration of insecticides. Our results suggest a new avenue for the protection of bees against sublethal cognitive effects of insecticides. © 2022. Published by The Company of Biologists Ltd.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Honey bees respond to multimodal stimuli following the principle of inverse effectiveness

Multisensory integration is assumed to entail benefits for receivers across multiple ecological contexts. However, signal integration effectiveness is constrained by features of the spatiotemporal and intensity domains. How sensory modalities are integrated during tasks facilitated by learning and memory, such as pollination, remains unsolved. Honey bees use olfactory and visual cues during foraging, making them a good model to study the use of multimodal signals. Here, we examined the effect of stimulus intensity on both learning and memory performance of bees trained using unimodal or bimodal stimuli. We measured the performance and the latency response across planned discrete levels of stimulus intensity. We employed the conditioning of the proboscis extension response protocol in honey bees using an electromechanical setup allowing us to control simultaneously and precisely olfactory and visual stimuli at different intensities. Our results show that the bimodal enhancement during learning and memory was higher as the intensity decreased when the separate individual components were least effective. Still, this effect was not detectable for the latency of response. Remarkably, these results support the principle of inverse effectiveness, traditionally studied in vertebrates, predicting that multisensory stimuli are more effectively integrated when the best unisensory response is relatively weak. Thus, we argue that the performance of the bees while using a bimodal stimulus depends on the interaction and intensity of its individual components. We further hold that the inclusion of findings across all levels of analysis enriches the traditional understanding of the mechanics and reliance of complex signals in honey bees. © 2022. Published by The Company of Biologists Ltd.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

The flavonoid kaempferol protects the fruit fly Drosophila melanogaster against the motor impairment produced by exposure to the insecticide fipronil

Exposure to pesticides across species has been associated with cognitive and motor impairments. As the problem impacts ecosystem stability, food production and public health, it is urgent to develop multifactorial solutions, from regulatory legislation to pharmacological alternatives that ameliorate the impairments. Fipronil, a commonly used insecticide, acts as a GABAA receptor (GABAAR) antagonist and induces motor impairments in vertebrates and invertebrates. Here, we hypothesized that kaempferol, a secondary metabolite derived from plants, acting as an allosteric modulator of GABAARs, would protect against the negative effects induced by the administration of fipronil in adults of the fruit fly Drosophila melanogaster. We further evaluated our hypothesis via co-administration of flumazenil, a competitive antagonist on the GABAAR, and through in silico analyses. We administered kaempferol prophylactically at three concentrations (10, 30 and 50 µmol l-1) and evaluated its protective effects against motor impairments induced by fipronil. We then used a single dose of kaempferol (50 µmol l-1) to evaluate its protective effect while administering flumazenil. We found that oral administration of fipronil impaired motor control and walking ability. In contrast, kaempferol was innocuous and protected flies from developing the motor-impaired phenotype, whereas the co-administration of flumazenil counteracted these protective effects. These results are supported by the binding of the ligands with the receptor. Together, our results suggest that kaempferol exerts a protective effect against fipronil via positive allosteric modulation of GABAARs, probably within brain areas such as the central complex and the mushroom bodies. These findings further support current attempts to use metabolites derived from plants as protectors against impairments produced by pesticides. © 2022. Published by The Company of Biologists Ltd.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Biologia reprodutiva de Psychotria spectabilis Steyrm. e Palicourea cf. virens (Poepp & Endl.) Standl. (Rubiaceae) em uma floresta tropical úmida na região de Manaus, AM, Brasil Reproductive biology of Psychotria spectabilis Steyrm. and Palicourea cf. virens (Poepp. & Endl.) Standl. (Rubiaceae) in a moist tropical forest at Manaus, Amazonas State, Brazil

Este estudo descreve a fenologia reprodutiva, morfologia e biologia floral, polinização e sucesso reprodutivo de Psychotria spectabilis e Palicourea cf. virens. Psychotria spectabilis floresceu de setembro a dezembro enquanto Palicourea cf. virens floresceu de maio a outubro. As inflorescências de Psychotria spectabilis são inflorescências terminais do tipo capítulo, com brácteas amarelas, flores brancas e heterostilia associada a diferenças na papila estigmática. Palicourea cf. virens apresenta inflorescências terminais do tipo corimbo, com flores amarelas homostílicas. Os recursos florais oferecidos foram néctar e pólen em ambas as espécies. Os beija-flores Phaethornis bourcieri e o macho de Thalurania furcata foram os principais visitantes florais de Psychotria spectabilis. Palicourea cf. virens também foi visitada por Thalurania furcata, com maior freqüência de visitas pela fêmea desta espécie. A abelha Trigona fulviventris visitou as flores das duas espécies, mas se comportou como pilhadora. O sucesso reprodutivo pré-emergente (SRPE) das duas espécies foi baixo, embora tenham apresentado um alto potencial reprodutivo.<br>This study describes the reproductive phenology, floral biology, pollination and reproductive success of Psychotria spectabilis and Palicourea cf. virens. Psychotria spectabilis flowered from September to December while P. cf. virens flowered from May to October. The terminal inflorescence of Psychotria spectabilis is of the capitate type with yellow bracts, white flowers and heterostyly associated with differences of stigmatic papillae. The terminal inflorescence of Palicourea cf. virens is a corymb with yellow, homostylous flowers. Flower resources include nectar and pollen for both species. The hummingbirds Phaethornis bourcieri and the male of Thalurania furcata were the main floral visitors of Psychotria spectabilis. Palicourea cf. virens was also visited by T. furcata, but the female was the main visitor. Trigona fulviventris visited flowers of both species, but was considered a thief. Pre-emergent reproductive success (PERS) of these two species was low, although they showed high reproductive potential