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1.
Nature ; 618(7963): 57-62, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36972685

RESUMO

Exploiting the excellent electronic properties of two-dimensional (2D) materials to fabricate advanced electronic circuits is a major goal for the semiconductor industry1,2. However, most studies in this field have been limited to the fabrication and characterization of isolated large (more than 1 µm2) devices on unfunctional SiO2-Si substrates. Some studies have integrated monolayer graphene on silicon microchips as a large-area (more than 500 µm2) interconnection3 and as a channel of large transistors (roughly 16.5 µm2) (refs. 4,5), but in all cases the integration density was low, no computation was demonstrated and manipulating monolayer 2D materials was challenging because native pinholes and cracks during transfer increase variability and reduce yield. Here, we present the fabrication of high-integration-density 2D-CMOS hybrid microchips for memristive applications-CMOS stands for complementary metal-oxide-semiconductor. We transfer a sheet of multilayer hexagonal boron nitride onto the back-end-of-line interconnections of silicon microchips containing CMOS transistors of the 180 nm node, and finalize the circuits by patterning the top electrodes and interconnections. The CMOS transistors provide outstanding control over the currents across the hexagonal boron nitride memristors, which allows us to achieve endurances of roughly 5 million cycles in memristors as small as 0.053 µm2. We demonstrate in-memory computation by constructing logic gates, and measure spike-timing dependent plasticity signals that are suitable for the implementation of spiking neural networks. The high performance and the relatively-high technology readiness level achieved represent a notable advance towards the integration of 2D materials in microelectronic products and memristive applications.

2.
Forensic Sci Med Pathol ; 19(4): 541-550, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-36705884

RESUMO

Arterial gas embolism following pulmonary barotrauma occurs in 13-24% of cases of diving deaths. The study aimed to evaluate the usefulness of a histomorphometric digital analysis in the detection of air space over-distension due to pulmonary barotrauma. The study was performed on lung parenchyma specimens of 12 divers: six had died due to arterial gas embolism following pulmonary barotrauma (mean age at death of 54 years, range of 41-61 years), and six had drowned in saltwater without a diagnosis of pulmonary barotrauma (mean age at death of 54 years, range of 41-66 years) (positive controls). For negative controls, six cases of non-SCUBA divers (mean age of death of 42 years, range of 23-55 years) who died of intracerebral haemorrhage were evaluated. No significant differences were observed in the characteristics of the air spaces between control groups (positive and negative). However, differences were observed in the area occupied by air spaces and the percentage of air space area when we compared the case group to the controls (p < 0.01); and there was a slight difference in the maximum and minimum diameters of air space (p < 0.05). The mean area occupied by air spaces and the mean percentage of air space were the most useful for discriminating pulmonary barotrauma from other causes of death (100% sensitivity and 91.7% specificity). Based on our study, inclusion of an increased pattern of air spaces as a possible diagnostic criterion for pulmonary barotrauma would be useful in discerning the cause of diving death.


Assuntos
Barotrauma , Mergulho , Afogamento , Embolia Aérea , Lesão Pulmonar , Humanos , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso , Mergulho/efeitos adversos , Embolia Aérea/patologia
3.
Mol Ecol ; 31(8): 2223-2241, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35146819

RESUMO

Heterogeneous seascapes and strong environmental gradients in coastal waters are expected to influence adaptive divergence, particularly in species with large population sizes where selection is expected to be highly efficient. However, these influences might also extend to species characterized by strong social structure, natal philopatry and small home ranges. We implemented a seascape genomic study to test this hypothesis in Indo-Pacific bottlenose dolphins (Tursiops aduncus) distributed along the environmentally heterogeneous coast of southern Australia. The data sets included oceanographic and environmental variables thought to be good predictors of local adaptation in dolphins and 8081 filtered single nucleotide polymorphisms (SNPs) genotyped for individuals sampled from seven different bioregions. From a neutral perspective, population structure and connectivity of the dolphins were generally influenced by habitat type and social structuring. Genotype-environment association analysis identified 241 candidate adaptive loci and revealed that sea surface temperature and salinity gradients influenced adaptive divergence in these animals at both large- (1000 km) and fine-scales (<100 km). Enrichment analysis and annotation of candidate genes revealed functions related to sodium-activated ion transport, kidney development, adipogenesis and thermogenesis. The findings of spatial adaptive divergence and inferences of putative physiological adaptations challenge previous suggestions that marine megafauna is most likely to be affected by environmental and climatic changes via indirect, trophic effects. Our work contributes to conservation management of coastal bottlenose dolphins subjected to anthropogenic disturbance and to efforts of clarifying how seascape heterogeneity influences adaptive diversity and evolution in small cetaceans.


Assuntos
Golfinho Nariz-de-Garrafa , Animais , Golfinho Nariz-de-Garrafa/genética , Ecossistema , Genômica , Salinidade , Temperatura
4.
J Mol Evol ; 87(9-10): 327-342, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31701178

RESUMO

Twenty-nine DNA regions of plastid origin have been previously identified in the mitochondrial genome of Cucurbita pepo (pumpkin; Cucurbitaceae). Four of these regions harbor homolog sequences of rbcL, matK, rpl20-rps12 and trnL-trnF, which are widely used as molecular markers for phylogenetic and phylogeographic studies. We extracted the mitochondrial copies of these regions based on the mitochondrial genome of C. pepo and, along with published sequences for these plastome markers from 13 Cucurbita taxa, we performed phylogenetic molecular analyses to identify inter-organellar transfer events in the Cucurbita phylogeny and changes in their nucleotide substitution rates. Phylogenetic reconstruction and tree selection tests suggest that rpl20 and rbcL mitochondrial paralogs arose before Cucurbita diversification whereas the mitochondrial matK and trnL-trnF paralogs emerged most probably later, in the mesophytic Cucurbita clade. Nucleotide substitution rates increased one order of magnitude in all the mitochondrial paralogs compared to their original plastid sequences. Additionally, mitochondrial trnL-trnF sequences obtained by PCR from nine Cucurbita taxa revealed higher nucleotide diversity in the mitochondrial than in the plastid copies, likely related to the higher nucleotide substitution rates in the mitochondrial region and loss of functional constraints in its tRNA genes.


Assuntos
Cucurbita/genética , Genoma Mitocondrial/genética , Plastídeos/genética , Evolução Biológica , Evolução Molecular , Genes de Plantas/genética , Genoma de Planta/genética , Mitocôndrias/genética , Filogenia , Análise de Sequência de DNA
5.
Forensic Sci Med Pathol ; 15(2): 224-232, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30915609

RESUMO

To describe the technical characteristics of fatal diving mishaps and to elucidate the causes of death using a sequence analysis and a multidisciplinary investigation of diving-related fatalities. All cases of diving deaths recorded on the coast of Girona (Spain) between January 2009 and May 2018 were analyzed. Most data were obtained from the police technical reports and the forensic pathology service. Each accident was analyzed in order to identify the trigger, disabling agent, disabling injury, and cause of death. During the study period 25 diving-related fatalities were recorded. Most of the victims were males aged 50-69 years, and 11 were experienced divers. Almost all victims were using open-circuit SCUBA to breathe with compressed air as their sole gas supply. None of the victims were diving alone. The most common identified triggers included exertion, panic, buoyancy problems, disorientation and confusion. The main factors identified as disabling agents were rapid ascent, a cardiac incident, panic and entrapment. Asphyxia, lung over expansion, and myocardial ischemia were the most frequent disabling injuries. Finally, drowning represented the main cause of death, followed by arterial gas embolism and natural causes or internal diseases. A differential diagnosis, performed in the setting of a multidisciplinary investigation, is essential for elucidating the cause of death in diving-related fatalities. The proposed sequence analysis allows to clarify underlying problems in these cases and to identify risk factors and unsafe behaviors in diving.


Assuntos
Barotrauma/mortalidade , Mergulho/efeitos adversos , Afogamento/mortalidade , Embolia Aérea/mortalidade , Acidentes/mortalidade , Adulto , Distribuição por Idade , Idoso , Asfixia/mortalidade , Confusão , Feminino , Humanos , Lesão Pulmonar/mortalidade , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/mortalidade , Pânico , Esforço Físico , Edema Pulmonar/mortalidade , Distribuição por Sexo , Adulto Jovem
6.
Forensic Sci Med Pathol ; 14(1): 18-25, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29460254

RESUMO

The purpose of this study was to suggest modifications of autopsy techniques in order to improve post-mortem diagnosis of arterial gas embolism (AGE) based on multidisciplinary investigation of SCUBA diving fatalities. Five adult human cadavers from the voluntary donation program of the Human Anatomy Laboratory, and eight judicial autopsied bodies of SCUBA divers from the Forensic Pathology Service were assessed. Before performing any autopsies, we accessed the diving plan and the divers' profiles for each case. We then introduced a new dissection procedure that included identification, isolation, and manipulation of carotid, vertebral and thoracic arterial systems. The dissected vascular structures that allowed optimall isolation of the systemic arterial circulation were identified and ligated. In three of the eight judicial cases, we had a strongly suggestive history of arterial gas embolism following pulmonary barotrauma (PBt/AGE). In these cases, the additional arterial dissection allowed us to clearly diagnose AGE in one of them. The autopsy of the rest of the cases showed other causes of death such as asphyxia by drowning and heart attack. In all cases we were able to reject decompression sickness, and in some of them we showed the presence of artefacts secondary to decomposition and resuscitation maneuvers. These results allow us to suggest a specific autopsy technique divided into four steps, aimed at confirming or excluding some evidence of dysbaric disorders according to a re-enactment of the incident. We have demonstrated the presence of large volumes of intravascular air, which is typical of PBt/AGE.


Assuntos
Artérias/patologia , Autopsia/métodos , Mergulho/efeitos adversos , Embolia Aérea/patologia , Idoso , Barotrauma/complicações , Embolia Aérea/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
7.
Medicina (B Aires) ; 75(6): 404-6, 2015.
Artigo em Espanhol | MEDLINE | ID: mdl-26707665

RESUMO

The co-inheritance of erythrocyte defects, hemoglobinopathies, enzymopathies, and membranopathies is not an unusual event. For the diagnosis, a laboratory strategy, including screening and confirmatory tests, additional to molecular characterization, was designed. As the result of this approach, a 24-year-old man carrying a hemoglobinopathy (Hemoglobin Woodville) and an enzymopathy (glucose-6-phosphate dehydrogenase deficiency) was identified. In the heterozygous state hemoglobin Woodville, is asymptomatic, and homozygous or double heterozygous individuals have not been reported thus far. On the other hand, previously described double point mutation in the gene for glucose-6-phosphate dehydrogenase c. [202G>A; 376A>G], p. [Val 68Met; Asn126Asp], causes hemolysis of varying severity after food or drug intake or infections. This case highlights the importance of the methodology carried out for the diagnosis, treatment, and proper genetic counseling.


Assuntos
Deficiência de Glucosefosfato Desidrogenase/genética , Glucosefosfato Desidrogenase/genética , Hemoglobinopatias/complicações , Hemoglobinas Anormais/genética , Mutação Puntual , Pré-Escolar , Aconselhamento Genético , Deficiência de Glucosefosfato Desidrogenase/complicações , Hemoglobinopatias/genética , Hemólise , Heterozigoto , Humanos , Masculino , Adulto Jovem
8.
Hemoglobin ; 38(6): 444-6, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25268796

RESUMO

ß-Thalassemia intermedia (ß-TI) patients present with a wide spectrum of phenotypes depending on the presence of primary, secondary, and tertiary genetic modifiers which modulate, by different mechanisms, the degree of imbalance between α and ß chains. Here we describe a new ß(0) frameshift mutation, HBB: c.44delT (p.Leu14ArgfsX5), identified in four members of a family, associated with secondary genetic modifiers in three of them. The different genotype present in this family was suspected after hematological analysis and thorough observation of blood smears highlighting their importance in the identification of ß-TI patients among members of the same family.


Assuntos
Família , Mutação da Fase de Leitura , Genes Modificadores , Hemoglobinas Anormais/genética , Globinas beta/genética , Talassemia beta/genética , Adulto , Argentina , Feminino , Humanos , Masculino
9.
PLoS One ; 19(5): e0303802, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38768189

RESUMO

The innovative performance of manufacturing and service companies can be impacted by the existing relationship between open innovation (OI) and the generation of confidentiality agreements (NDAs) as a tool for the protection of intellectual property. Based on the analysis of a cross-sectional sample of 6,798 industrial companies (2019-2020) and 9,304 companies in the service sector (2017-2019) that are part of the directory of the National Administrative Department of Statistics (DANE) in its Technological Innovation and Development Survey (EDIT and EDITS), it can be suggested that the interaction of these two variables (OI and NDAs) generate positive effects for the manufacturing industry but negative ones for the service sector. It could be deduced that the positive effect is due to the greater tradition of OI in the manufacturing industry and the negative effect to the caution that the service sector presents when collaborating with external actors.


Assuntos
Confidencialidade , Humanos , Estudos Transversais , Indústria Manufatureira , Invenções , Propriedade Intelectual , Indústrias , Inquéritos e Questionários
10.
Nat Commun ; 15(1): 1974, 2024 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-38438350

RESUMO

Artificial Intelligence (AI) is currently experiencing a bloom driven by deep learning (DL) techniques, which rely on networks of connected simple computing units operating in parallel. The low communication bandwidth between memory and processing units in conventional von Neumann machines does not support the requirements of emerging applications that rely extensively on large sets of data. More recent computing paradigms, such as high parallelization and near-memory computing, help alleviate the data communication bottleneck to some extent, but paradigm- shifting concepts are required. Memristors, a novel beyond-complementary metal-oxide-semiconductor (CMOS) technology, are a promising choice for memory devices due to their unique intrinsic device-level properties, enabling both storing and computing with a small, massively-parallel footprint at low power. Theoretically, this directly translates to a major boost in energy efficiency and computational throughput, but various practical challenges remain. In this work we review the latest efforts for achieving hardware-based memristive artificial neural networks (ANNs), describing with detail the working principia of each block and the different design alternatives with their own advantages and disadvantages, as well as the tools required for accurate estimation of performance metrics. Ultimately, we aim to provide a comprehensive protocol of the materials and methods involved in memristive neural networks to those aiming to start working in this field and the experts looking for a holistic approach.

11.
Rev Bras Ortop (Sao Paulo) ; 58(1): 85-91, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36969781

RESUMO

Objective To analyze the dimensions of the posterior cruciate ligament (PCL), anterior cruciate ligament (ACL), the presence of meniscus-femoral ligaments MFLs in human knees, and the correlation with the dimensions of the knee skeleton. Methods Anatomical study on 29 specimens of human knees in which we measured the length and width of the cruciate and meniscus-femoral ligaments and the dimensions of femoral and tibia condyles and the femoral notch. The ACL length was calculated with different degrees of knee flexion. The relationship between the ligaments and bone dimensions were analyzed. Results The length of the ACL and the PCL were similar. Posterior MFL was more frequent and longer than the anterior MFL. We found the posterior MFL in the 72.41% of the knees and anterior MFL in 20.69%. The ACL presented 30% of its maximum length up to 60°, approximately half of its length between 90° and 120°, reaching its maximum length at 170°. We found a strong correlation between the length of the ACL and that of the PCL ( p = 0.001). However, the lengths of the ACL and PCL were not related with the bone dimensions. Conclusion We have found no correlations between the cruciate and MFLs and the anatomical dimensions of the intercondylar notch and the proximal tibia and distal femur. The presence of the posterior MFL was more frequent and longer than that of the anterior ligament.

12.
Arch Argent Pediatr ; 121(5): e202202801, 2023 10 01.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-36857142

RESUMO

Hemoglobinopathies are genetic disorders that affect the hemoglobin (Hb) molecule. Mutations in the alpha or beta chains altering the Hb tetramer may modify the molecule's oxygen-binding capacity. Hemoglobinopathies with low oxygen affinity may occur with cyanosis and an altered pulse oximetry reading, leading to unnecessary and sometimes invasive tests to rule out cardiovascular and respiratory conditions. In the case report described here, we present an asymptomatic pediatric patient who consulted for desaturated pulse oximetry. Her initial laboratory tests showed normocytic, normochromic anemia. Venous blood gas samples showed an elevated p50. After using extensive diagnostic tools, a variant of Hb with low oxygen affinity was diagnosed: Hb Denver.


Las hemoglobinopatías son trastornos genéticos que afectan a la molécula de hemoglobina (Hb). Las mutaciones en las cadenas a o b que alteran el tetrámero de Hb pueden modificar la capacidad de la molécula para unirse al oxígeno. Las hemoglobinopatías con baja afinidad al oxígeno pueden presentarse con cianosis y una lectura alterada de la oximetría de pulso, lo que lleva a pruebas innecesarias y, a veces, invasivas para descartar afecciones cardiovasculares y respiratorias. En el siguiente reporte de caso, presentamos a una paciente pediátrica, asintomática, que se presentó a la consulta por detección de desaturación en oximetría de pulso. Las pruebas de laboratorio iniciales mostraron una anemia normocítica, normocrómica. Las muestras de gas venoso demostraron una p50 elevada. Después de extensas herramientas de diagnóstico, se diagnosticó una variante de Hb con baja afinidad al oxígeno, Hb Denver.


Assuntos
Anemia , Hemoglobinopatias , Hemoglobinas Anormais , Humanos , Criança , Feminino , Hemoglobinas Anormais/genética , Hemoglobinas Anormais/análise , Hemoglobinas Anormais/química , Oximetria , Hemoglobinopatias/diagnóstico , Hemoglobinopatias/genética , Oxigênio
13.
Nanoscale ; 15(5): 2171-2180, 2023 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-36628646

RESUMO

The development of the internet-of-things requires cheap, light, small and reliable true random number generator (TRNG) circuits to encrypt the data-generated by objects or humans-before transmitting them. However, all current solutions consume too much power and require a relatively large battery, hindering the integration of TRNG circuits on most objects. Here we fabricated a TRNG circuit by exploiting stable random telegraph noise (RTN) current signals produced by memristors made of two-dimensional (2D) multi-layered hexagonal boron nitride (h-BN) grown by chemical vapor deposition and coupled with inkjet-printed Ag electrodes. When biased at small constant voltages (≤70 mV), the Ag/h-BN/Ag memristors exhibit RTN signals with very low power consumption (∼5.25 nW) and a relatively high current on/off ratio (∼2) for long periods (>1 hour). We constructed TRNG circuits connecting an h-BN memristor to a small, light and cheap commercial microcontroller, producing a highly-stochastic, high-throughput signal (up to 7.8 Mbit s-1) even if the RTN at the input gets interrupted for long times up to 20 s, and if the stochasticity of the RTN signal is reduced. Our study presents the first full hardware implementation of 2D-material-based TRNGs, enabled by the unique stability and figures of merit of the RTN signals in h-BN based memristors.

14.
Genome Biol Evol ; 15(11)2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37935115

RESUMO

Climatic changes have caused major environmental restructuring throughout the world's oceans. Marine organisms have responded to novel conditions through various biological systems, including genomic adaptation. Growing accessibility of next-generation DNA sequencing methods to study nonmodel species has recently allowed genomic changes underlying environmental adaptations to be investigated. This study used double-digest restriction-site associated DNA (ddRAD) sequence data to investigate the genomic basis of ecotype formation across currently recognized species and subspecies of bottlenose dolphins (genus Tursiops) in the Southern Hemisphere. Subspecies-level genomic divergence was confirmed between the offshore common bottlenose dolphin (T. truncatus truncatus) and the inshore Lahille's bottlenose dolphin (T. t. gephyreus) from the southwestern Atlantic Ocean (SWAO). Similarly, subspecies-level divergence is suggested between inshore (eastern Australia) Indo-Pacific bottlenose dolphin (T. aduncus) and the proposed Burrunan dolphin (T. australis) from southern Australia. Inshore bottlenose dolphin lineages generally had lower genomic diversity than offshore lineages, a pattern particularly evident for T. t. gephyreus, which showed exceptionally low diversity. Genomic regions associated with cardiovascular, musculoskeletal, and energy production systems appear to have undergone repeated adaptive evolution in inshore lineages across the Southern Hemisphere. We hypothesize that comparable selective pressures in the inshore environment drove similar adaptive responses in each lineage, supporting parallel evolution of inshore bottlenose dolphins. With climate change altering marine ecosystems worldwide, it is crucial to gain an understanding of the adaptive capacity of local species and populations. Our study provides insights into key adaptive pathways that may be important for the long-term survival of cetaceans and other organisms in a changing marine environment.


Assuntos
Golfinho Nariz-de-Garrafa , Animais , Golfinho Nariz-de-Garrafa/genética , Ecossistema , Ecótipo , Cetáceos , Genômica
15.
J Clin Oncol ; 41(14): 2561-2570, 2023 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-36821809

RESUMO

PURPOSE: In many cancers, the expression of immunomodulatory ligands leads to immunoevasion, as exemplified by the interaction of PD-L1 with PD-1 on tumor-infiltrating lymphocytes. Profound advances in cancer treatments have come with the advent of immunotherapies directed at blocking these immuno-suppressive ligand-receptor interactions. However, although there has been success in the use of these immune checkpoint interventions, correct patient stratification for these therapies has been challenging. MATERIALS AND METHODS: To address this issue of patient stratification, we have quantified the intercellular PD-1/PD-L1 interaction in formalin-fixed paraffin-embedded tumor samples from patients with non-small cell lung carcinoma, using a high-throughput automated quantitative imaging platform (quantitative functional proteomics [QF-Pro]). RESULTS: The multisite blinded analysis across a cohort of 188 immune checkpoint inhibitor-treated patients demonstrated the intra- and intertumoral heterogeneity of PD-1/PD-L1 immune checkpoint engagement and notably showed no correlation between the extent of PD-1/PD-L1 interaction and PD-L1 expression. Importantly, PD-L1 expression scores used clinically to stratify patients correlated poorly with overall survival; by contrast, patients showing a high PD-1/PD-L1 interaction had significantly better responses to anti-PD-1/PD-L1 treatments, as evidenced by increased overall survival. This relationship was particularly strong in the setting of first-line treatments. CONCLUSION: The functional readout of PD-1/PD-L1 interaction as a predictive biomarker for the stratification of patients with non-small-cell lung carcinoma, combined with PD-L1 expression, should significantly improve the response rates to immunotherapy. This would both capture patients excluded from checkpoint immunotherapy (high PD-1/PD-L1 interaction but low PD-L1 expression, 24% of patients) and additionally avoid treating patients who despite their high PD-L1 expression do not respond and suffer from side effects.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Imunoterapia/métodos , Antígeno B7-H1
16.
Micromachines (Basel) ; 13(2)2022 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-35208454

RESUMO

This paper reports the fundamentals and the SPICE implementation of the Dynamic Memdiode Model (DMM) for the conduction characteristics of bipolar-type resistive switching (RS) devices. Following Prof. Chua's memristive devices theory, the memdiode model comprises two equations, one for the electron transport based on a heuristic extension of the quantum point-contact model for filamentary conduction in thin dielectrics and a second equation for the internal memory state related to the reversible displacement of atomic species within the oxide film. The DMM represents a breakthrough with respect to the previous Quasi-static Memdiode Model (QMM) since it describes the memory state of the device as a balance equation incorporating both the snapback and snapforward effects, features of utmost importance for the accurate and realistic simulation of the RS phenomenon. The DMM allows simple setting of the initial memory condition as well as decoupled modeling of the set and reset transitions. The model equations are implemented in the LTSpice simulator using an equivalent circuital approach with behavioral components and sources. The practical details of the model implementation and its modes of use are also discussed.

17.
Adv Mater ; 34(20): e2201197, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35320590

RESUMO

The development of memristors operating at low switching voltages <50 mV can be very useful to avoid signal amplification in many types of circuits, such as those used in bioelectronic applications to interact with neurons and nerves. Here, it is reported that 400 nm-thick films made of dalkyl-dithiophosphoric (DDP) modified copper nanoparticles (CuNPs) exhibit volatile threshold-type resistive switching (RS) at ultralow switching voltage of ≈4 mV. The RS is observed in small nanocells with a lateral size of <50 nm-2 , during hundreds of cycles, and with an ultralow variability. Atomistic calculations reveal that the switching mechanism is related to the modification of the Schottky barriers and insulator-to-metal transition when ionic movement is induced via external bias. The devices are also used to model integrate-and-fire neurons for spiking neural networks and it is concluded that circuits employing DDP-CuNPs consume around ten times less power than similar neurons implemented with a memristor that switches at 40 mV.


Assuntos
Cobre , Nanopartículas , Metais , Redes Neurais de Computação , Neurônios
18.
Micromachines (Basel) ; 13(11)2022 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-36422434

RESUMO

In this paper, the use of Artificial Neural Networks (ANNs) in the form of Convolutional Neural Networks (AlexNET) for the fast and energy-efficient fitting of the Dynamic Memdiode Model (DMM) to the conduction characteristics of bipolar-type resistive switching (RS) devices is investigated. Despite an initial computationally intensive training phase the ANNs allow obtaining a mapping between the experimental Current-Voltage (I-V) curve and the corresponding DMM parameters without incurring a costly iterative process as typically considered in error minimization-based optimization algorithms. In order to demonstrate the fitting capabilities of the proposed approach, a complete set of I-Vs obtained from Y2O3-based RRAM devices, fabricated with different oxidation conditions and measured with different current compliances, is considered. In this way, in addition to the intrinsic RS variability, extrinsic variation is achieved by means of external factors (oxygen content and damage control during the set process). We show that the reported method provides a significant reduction of the fitting time (one order of magnitude), especially in the case of large data sets. This issue is crucial when the extraction of the model parameters and their statistical characterization are required.

19.
Ginecol Obstet Mex ; 79(4): 190-5, 2011 Apr.
Artigo em Espanhol | MEDLINE | ID: mdl-21966805

RESUMO

BACKGROUND: The preeclampsia is a multisystemic syndrome that occupied the first cause of maternal and fetal mortality around the world. Epidemiologic studies shown both mother and father contribute at the same risk for preeclampsia. OBJECTIVE: To determinate if there is an association between preeclampsia and paternal age. MATERIAL AND METHOD: Preeclampsia-eclampsia patients and couples were analyzed in agree to "National High Blood Pressure Education Program Working Group" classification, and a control group constituted by normal pregnant women and couples was included. RESULTS: There were 27 cases with mild preeclampsia and her couples, 13 cases with severe preeclampsia and her couples and 40 controls conformed by normal pregnant women and her couples. The statistical analysis of variance of the ages shown that men from preeclamptic group had a greater variance in contrast with man of control group (p < 0.001; valor of F = 5.084). CONCLUSIONS: Although is not clear how paternal age interview in preeclampsia risk, the interaction between paternal-maternal imprinting and spermatic senescence, followed by shortened telomeres of chromosome, could be produce the inactivity of a whole network of signals implicated in disease aetiology.


Assuntos
Eclampsia/epidemiologia , Idade Paterna , Pré-Eclâmpsia/epidemiologia , Adulto , Causalidade , Diabetes Mellitus/genética , Feminino , Impressão Genômica , Humanos , Hipertensão/genética , Masculino , Idade Materna , Pessoa de Meia-Idade , Modelos Biológicos , Projetos Piloto , Gravidez , Risco , Adulto Jovem
20.
Chemosphere ; 272: 129920, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33607495

RESUMO

In this work a polymer inclusion membrane (PIM) is proposed as passive sampler material and compared with two filamentous fungi for As (V) uptake to evaluate its ability as chemical surrogate material for the monitoring of this metalloid in aquatic environments. Results show excellent passive sampling characteristics of the device since a linear uptake profile as a function of time was observed. The correlation coefficients between the PIM passive sampler with Aspergillus niger (r = 0.83) and Rhizopus sp. (r = 0.13) uptake, show that the first species is the best modeled by the PIM, suggesting its potential as a chemical substitute in bioavailability studies.


Assuntos
Aspergillus niger , Rhizopus , Meios de Cultura , Fungos , Polímeros , Água
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