Biophysical parameters control signal transfer in spiking network

IntroductionInformation transmission and representation in both natural and artificial networks is dependent on connectivity between units. Biological neurons, in addition, modulate synaptic dynamics and post-synaptic membrane properties, but how these relate to information transmission in a population of neurons is still poorly understood. A recent study investigated local learning rules and showed how a spiking neural network can learn to represent continuous signals. Our study builds on their model to explore how basic membrane properties and synaptic delays affect information transfer.MethodsThe system consisted of three input and output units and a hidden layer of 300 excitatory and 75 inhibitory leaky integrate-and-fire (LIF) or adaptive integrate-and-fire (AdEx) units. After optimizing the connectivity to accurately replicate the input patterns in the output units, we transformed the model to more biologically accurate units and included synaptic delay and concurrent action potential generation in distinct neurons. We examined three different parameter regimes which comprised either identical physiological values for both excitatory and inhibitory units (Comrade), more biologically accurate values (Bacon), or the Comrade regime whose output units were optimized for low reconstruction error (HiFi). We evaluated information transmission and classification accuracy of the network with four distinct metrics: coherence, Granger causality, transfer entropy, and reconstruction error.ResultsBiophysical parameters showed a major impact on information transfer metrics. The classification was surprisingly robust, surviving very low firing and information rates, whereas information transmission overall and particularly low reconstruction error were more dependent on higher firing rates in LIF units. In AdEx units, the firing rates were lower and less information was transferred, but interestingly the highest information transmission rates were no longer overlapping with the highest firing rates.DiscussionOur findings can be reflected on the predictive coding theory of the cerebral cortex and may suggest information transfer qualities as a phenomenological quality of biological cells

Biophysical parameters control signal transfer in spiking network

IntroductionInformation transmission and representation in both natural and artificial networks is dependent on connectivity between units. Biological neurons, in addition, modulate synaptic dynamics and post-synaptic membrane properties, but how these relate to information transmission in a population of neurons is still poorly understood. A recent study investigated local learning rules and showed how a spiking neural network can learn to represent continuous signals. Our study builds on their model to explore how basic membrane properties and synaptic delays affect information transfer. MethodsThe system consisted of three input and output units and a hidden layer of 300 excitatory and 75 inhibitory leaky integrate-and-fire (LIF) or adaptive integrate-and-fire (AdEx) units. After optimizing the connectivity to accurately replicate the input patterns in the output units, we transformed the model to more biologically accurate units and included synaptic delay and concurrent action potential generation in distinct neurons. We examined three different parameter regimes which comprised either identical physiological values for both excitatory and inhibitory units (Comrade), more biologically accurate values (Bacon), or the Comrade regime whose output units were optimized for low reconstruction error (HiFi). We evaluated information transmission and classification accuracy of the network with four distinct metrics: coherence, Granger causality, transfer entropy, and reconstruction error. ResultsBiophysical parameters showed a major impact on information transfer metrics. The classification was surprisingly robust, surviving very low firing and information rates, whereas information transmission overall and particularly low reconstruction error were more dependent on higher firing rates in LIF units. In AdEx units, the firing rates were lower and less information was transferred, but interestingly the highest information transmission rates were no longer overlapping with the highest firing rates. DiscussionOur findings can be reflected on the predictive coding theory of the cerebral cortex and may suggest information transfer qualities as a phenomenological quality of biological cells.Peer reviewe

Migratory restlessness in shorebirds (Aves, Charadriiformes). A case study by means of accelerometers

The knowledge of individual and environmental parameters affecting stopover length in shorebirds is important for the conservation and management of species and habitats often seriously threatened, such as Mediterranean wetlands. The role of external factors affecting the decision to leave a stopover site is not always easy to study in the field, due to the high number of variables (i.e., atmospheric conditions) potentially involved. Combining both field and laboratory research has proved to be extremely useful in order to identify the main factors affecting stopover length, at least in passerines. Recent studies demonstrated that the amount of migratory restlessness in these species can be considered a good proxy for quantifying the willingness to depart from a refuelling site. Even if shorebirds have proved to be good models for laboratory research, the only papers regarding migratory restlessness in this group concern studies on orientation mechanisms, which are mainly aimed at showing their use of magnetic compass. The present work aims at studying the migratory restlessness in shorebirds and its relation with body conditions and stopover length by using spring migrating Wood sandpiper (Tringa glareola) as a model species. Despite this method proved to be effective in recording Wood sandpipers activity, we failed to found any relationship among their stopover length, body conditions and nocturnal activity. The degree of nocturnal activity was overall low, whereas a peak in activity was registered at sunset. This twilight activity was oriented, and its amount varied significantly according to the amount of available food in captivity. Our results suggested that migratory restlessness in shorebirds might show some peculiar characteristics that would deserve further investigations

Analysis, design and construction of copper vapor laser system

In this work construction characteristics and performance of a small scale self-heating copper vapor laser are presented. Analytical design of the thermal isolator is reported in some detail. Particular attention has been given to the knowledge of power deposition in the discharge to evaluate the component losses. In the optimized conditions the laser mean power is over 5 W, confirming the expected values. Details of the measurements on the system are also reported

A Perspective on Recent Advances in Phosphorene Functionalization and its Application in Devices

Phosphorene, the 2D material derived from black phosphorus, has recently attracted a lot of interest for its properties, suitable for applications in material science. In particular, the physical features and the prominent chemical reactivity on its surface render this nanolayered substrate particularly promising for electrical and optoelectronic applications. In addition, being a new potential ligand for metals, it opens the way for a new role of the inorganic chemistry in the 2D world, with special reference to the field of catalysis. The aim of this review is to summarize the state of the art in this subject and to present our most recent results in preparation, functionalization and use of phosphorene and its decorated derivatives. In particular, we discuss several key points, which are currently under investigation: the synthesis, the characterization by theoretical calculations, the high pressure behaviour of black phosphorus, as well as decoration with nanoparticles and encapsulation in polymers. Finally, device fabrication and electrical transport measurements are overviewed on the basis of recent literature and new results collected in our laboratories

High tibial osteotomy in varus knees: indications and limits

Opening wedge high tibial osteotomy (OWHTO) is a surgical procedure that aims to correct the weight-bearing axis of the knee, moving the loads laterally from the medial compartment. Conventional indications for OWHTO are medial compartment osteoarthritis and varus malalignment of the knee; recently OWHTO has been used successfully in the treatment of double and triple varus. OWHTO, in contrast to closing wedge high tibial osteotomy, does not require fibular osteotomy or peroneal nerve dissection, or lead to disruption of the proximal tibiofibular joint and bone stock loss. For these reasons, interest in this procedure has grown in recent years. The aim of this study is to review the literature on OWHTO, considering indications and prognostic factors (body mass index, grade of osteoarthritis, instability, range of movement and age), outcomes at mid-term follow-up, and limits of the procedure (slope modifications, patellar height changes and difficulties in conversion to a total knee arthroplasty)

A cationic tetrapyrrole inhibits toxic activities of the cellular prion protein

Prion diseases are rare neurodegenerative conditions associated with the conformational conversion of the cellular prion protein (PrPC) into PrPSc, a self-replicating isoform (prion) that accumulates in the central nervous system of affected individuals. The structure of PrPSc is poorly defined, and likely to be heterogeneous, as suggested by the existence of different prion strains. The latter represents a relevant problem for therapy in prion diseases, as some potent anti-prion compounds have shown strain-specificity. Designing therapeutics that target PrPC may provide an opportunity to overcome these problems. PrPC ligands may theoretically inhibit the replication of multiple prion strains, by acting on the common substrate of any prion replication reaction. Here, we characterized the properties of a cationic tetrapyrrole [Fe(III)-TMPyP], which was previously shown to bind PrPC, and inhibit the replication of a mouse prion strain. We report that the compound is active against multiple prion strains in vitro and in cells. Interestingly, we also find that Fe(III)-TMPyP inhibits several PrPC-related toxic activities, including the channel-forming ability of a PrP mutant, and the PrPC-dependent synaptotoxicity of amyloid-beta (A beta) oligomers, which are associated with Alzheimer's Disease. These results demonstrate that molecules binding to PrPC may produce a dual effect of blocking prion replication and inhibiting PrPC-mediated toxicity

Primjena programa ubrzanog oporavka nakon barijatrijske kirurgije: analiza kliničkih ishoda i isplativosti

Enhanced recovery after surgery (ERAS) programs are perioperative evidencebased interventions that have the purpose of making the perioperative pathway more efficient in safeguarding patient safety and quality of care. Recently, several ERAS components have been introduced in the setting of bariatric surgery (Enhanced Recovery After Bariatric Surgery, ERABS). The aim of the present study was to evaluate clinical efficiency and cost-effectiveness of the implementation of an ERABS program. It was a retrospective case-control study comparing a group of adult obese (body mass index >40) patients treated according to the ERABS protocol (2014-2015) with a historical control group that received standard care (2013-2014) in the General and Emergency Surgery Department, Arcispedale S. Maria Nuova Hospital, Reggio Emilia, Italy. Data on the occurrence of complications, mortality, re-admissions and re-operations were extracted retrospectively from medical case notes and emergency patient admission lists. Length of hospital stay was significantly different between the two cohort patients. In the control group, the mean length of stay was 12.6±10.9 days, whereas in the ERABS cohort it was 7.1±2.9 days (p=0.02). During hospital stay, seven patients in the control group developed surgical complications, including one patient with major complications, whereas in the ERABS group three patients developed minor complications. Economic analysis revealed a different cost distribution between the two groups. On the whole, there were significant savings for almost all the variables taken into consideration, mainly driven by exclusion of using intensive are unit, which is by far more expensive than the average cost of post-anesthesia care unit. Our study confirmed the implementation of an ERABS protocol to have shortened hospital stay and was cost-saving while safeguarding patient safety.Programi ubrzanog oporavka nakon operacije (Enhanced Recovery After Surgery, ERAS) su perioperacijske intervencije zasnovane na dokazima kojima je svrha učiniti perioperacijski tijek učinkovitijim osiguravajući bolesnikovu sigurnost i kvalitetu skrbi. Odnedavno je nekoliko sastavnica programa ERAS uvedeno u okruženje barijatrijske kirurgije (Enhanced Recovery After Bariatric Surgery, ERABS). Cilj ovoga istraživanja bio je procijeniti kliničku učinkovitost i isplativost provođenja programa ERABS. U ovoj retrospektivnoj studiji slučaja i kontrola uspoređena je skupina odraslih pretilih bolesnika (indeks tjelesne mase >40) liječenih prema protokolu ERABS (2014.-2015.) s povijesnom kontrolnom skupinom koja je primala standardnu skrb (2013.-2014.) u Klinici za opću i hitnu kirurgiju, Bolnica Arcispedale S. Maria Nuova, Reggio Emilia, Italija. Podaci o pojavnosti komplikacija, smrtnosti, ponovnom prijmu i ponovljenim operacijama retrospektivno su izvedeni iz bolesničkih kartona i prijamnih lista. Duljina boravka u bolnici značajno se razlikovala među dvjema skupinama bolesnika. U kontrolnoj skupini srednja duljina boravka u bolnici bila je 12,6±10,9 dana, dok je skupini ERABS iznosila 7,1±2,9 dana (p=0,02). Kod prijma se kirurška komplikacija razvila u 7 osoba iz kontrolne skupine; od toga je jedan bolesnik imao teže komplikacije, dok su u skupini ERABS manje komplikacije zabilježene kod 3 bolesnika. Ekonomska analiza pokazala je drukčiju raspoređenost troškova u dvjema skupinama. Sve u svemu, značajne uštede u gotovo svim ispitivanim varijablama uglavnom su nastale zbog isključenja uporabe jedinice intenzivnog liječenja, što je daleko skuplje od prosječnih troškova u jedinici skrbi poslije anestezije. Naše je istraživanje potvrdilo da primjena protokola ERABS skraćuje boravak u bolnici i snižava troškove pritom osiguravajući sigurnost bolesnika

Checklist of macro-invertebrates of the special conservation area “Poggi di prata”(Grosseto, Central Italy) through a citizen-science and expert-based approach

The assessment of species composition in a certain area may become outdated over time due to community dynamics including species range expansion, but also to local extinctions, species introductions and taxonomic redefinition. Therefore, updated checklists are required for animal conservation and management. Exhaustive checklists of invertebrate species may be challenging, as species determination often requires the analysis by specialists, but they are fundamental for local conservation practices. In this work, we provided an annotated preliminary checklist of invertebrates of the Special Conservation Area “Poggi di Prata” (province of Grosseto, southern Tuscany), detected through field samplings with experts, and a permanent Bioblitz set out on an online citizen-science platform (iNaturalist.org). The final dataset (1898-2020) included 329 records of 282 species (217 insects, 34 gastropods, 30 arachnids and 1 chilopod). Most records were uploaded on iNaturalist (about 56.5%), others came from observations or sampling collections (37%) and were determined by specialists. Only the remaining 6.5% of records came from published studies. Three species were protected by the Habitat Directive, 15 by the Tuscan Regional Law. We also detected two endemic or near-endemic taxa of this area: the beetle Paramaurops diecki massetanus and the land snail Marmorana saxetana. The unexpected (Italian southernmost) record of Gaurotes virginea needs to be deepened. Furthermore, 12 alien species, including insects affecting human economy and wellness (e.g., Rhinchophorous ferrugineus, Aedes albopictus, Halyomorpha halys, Dryocosmus kuriphilus and Cydalima perspectalis), were also detected. With our work, we confirmed that citizen-science platforms (e.g. iNaturalist) are valuable tools, complementary to field-work by specialists, to map local biodiversity and they may help to improve biogeographical knowledge

Green and scalable synthesis of nanocrystalline kuramite

The new generation of solar cells aims to overcome many of the issues created by silicon-based devices (e.g., decommissioning, flexibility and high-energy production costs). Due to the scarcity of the resources involved in the process and the need for the reduction of potential pollution, a greener approach to solar cell material production is required. Among others, the solvothermal approach for the synthesis of nanocrystalline Cu-Sn-S (CTS) materials fulfils all of these requirements. The material constraints must be considered, not only for the final product, but for the whole production process. Most works reporting the successful synthesis of CTS have employed surfactants, high pressure or noxious solvents. In this paper, we demonstrate the synthesis of nanocrystalline kuramite by means of a simpler, greener and scalable solvothermal synthesis. We exploited a multianalytical characterization approach (X-ray diffraction, extended X-ray absorption fine structure, field emission scanning electron microscopy, Raman spectroscopy and electronic microprobe analysis (EMPA) to discriminate kuramite from other closely related polymorphs. Moreover, we confirmed the presence of structural defects due to a relevant antisite population