Time Lapse Research Articles

The neglected emotional drawbacks of the prioritization of embryos to transfer

In recent years, increasing efforts have been made to develop advanced techniques that could predict the potential of implantation of each single embryo and prioritize the transfer of those at higher chance. The most promising include non-invasive preimplantation genetic testing for aneuploidy and artificial intelligence-based algorithms using time lapse images. The psychological effect of these add-ons is neglected. One could speculate that embarking on another transfer after one or more failures with the prospect of receiving an embryo of lower potential may be distressing for the couple. In addition, the symbolic and mental representation of an embryo with ‘lower capacity to implant’ is currently unknown but could affect couples’ choices and wellbeing. These emotional responses may also undermine adherence to the programme and, ultimately, its real effectiveness. Future trials aimed at evaluating the validity of prioritization procedures must also consider the emotional burden on the couples.

Diurnal predators of restocked lab-reared and wild Diadema antillarum near artificial reefs in Saba.

The long-spined sea urchin Diadema antillarum controls reef dynamics by grazing on algae and increasing coral recruitment. Populations of Diadema never recovered after a mass-die off in 1983 and 1984, and numbers were further reduced by a more recent die-off in 2022. To restore grazing pressure and thereby the resilience of Caribbean coral reefs, multiple Diadema restocking efforts have been performed. Although results vary, relatively low retention is one of the reasons restocking is not considered more often. If causes for the low retention can be identified, suitable measures may be able to increase restocking success. In this study, we monitored restocked lab-reared and wild juvenile Diadema on artificial reefs around Saba, Caribbean Netherlands. To assess the retention of Diadema over time, we conducted diver surveys and used underwater photo time lapse during daylight. Retention of uncaged lab-reared and wild Diadema decreased steadily with less than 30% surviving after 10 days. In total, 138 predator-prey interactions were recorded, of which 99% involved the queen triggerfish Balistes vetula, although other potential predators were present in the area. None of the recorded predator-prey interactions was successful, which suggests that artificial reefs with incorporated shelters may be suitable for juveniles as daytime refuge. However, Diadema that were more often attacked during the day were more likely to be absent the next morning. Because queen triggerfish often visited the experimental site in the first or last hour of daylight, it could be that they were more successful in their attacks when it was too dark to see anything on the photos and when Diadema came out to feed or to look for better shelter opportunities. If Diadema migrated off the artificial reef, they were probably predated during the process, because no Diadema were found on surrounding reefs. Wild Diadema were attacked significantly more often than lab-reared Diadema, possibly because the wild urchins were larger, but this did not significantly affect retention. Future restocking should be performed on natural or artificial reefs with deeper shelters, so Diadema can retract farther into their crevice, and should include night-time monitoring to identify the remaining unknown factors that cause low retention, including migration and nocturnal predation. This knowledge is urgently needed to coral reef managers so they can increase Diadema restocking success by selecting reefs with a lower predator density, protect urchins during an acclimatization period and/or conduct temporary predator control measures.

Assessment of capillary rise in rocks by Time Lapse Digital Imaging

Solution flow can significantly influence metal recovery and kinetics in leaching, especially in heap/dump/In-situ leaching, however, the vast majority of the work in this area has focused on the inter-particle fluid flow, and only a few studies have investigated the capillary rise behaviour within rock samples. This deserves more attention because it plays a fundamental role in the recovery process and the diffusion pathways for lixiviants and reacted products. This short communication presents a simple methodology for the estimation of capillary action by testing different rock types by Time Lapse Digital Imaging. The method was sensitive to pixel variation which can be intercepted as the response in wettability variation. It can certainly be coupled with other technologies for ore characterization, such as X-ray micro-tomography, to further understand how the pore size distribution influences capillary response, and the fluid rise through pore spaces to interact with ore grains.

THU028 Novel Approach To Management Of Acromegaly With De Novo Oral Octreotide Or Combination Therapy With Cabergoline: A Case Series

Abstract Disclosure: A. Halstrom: None. G.A. Dobri: None. Acromegaly is a rare disorder characterized by tumoral hypersecretion of growth hormone (GH) leading to overproduction of insulin-like growth factor 1 (IGF-1). Patients present with physical changes, and systemic complications. Treatment involves surgery and medical therapy with the goal of normalizing IGF-1. First line medical therapy consists of first-generation injectable somatostatin receptor ligands (SRL) (octreotide LAR, lanreotide autogel). Dopamine agonists (cabergoline) can be used in patients with mild IGF-1 elevation. If IGF-1 levels do not normalize, pasireotide or pegvisomant can be tried. Until recently, SRLs were administered only as a deep tissue injection. Patients have reported injection site reactions, frustration, and breakthrough acromegaly symptoms between doses. Two trials were conducted which showed that oral octreotide is an effective alternative for patients after achieving biochemical control with the injectable formulation. Two cases are presented below in which patients with acromegaly were treated with de novo oral octreotide either or as combination therapy with cabergoline, after a significant time lapse since injection SRL. Our first case is a 24 year old female with a 19mm mammosomatotroph adenoma, resected 8 years prior, with questionable remnant on postoperative MRI and biochemically active acromegaly. She was started on octreotide LAR 20mg which was titrated up to 30mg. However, she had not achieved biochemical control, with lowest IGF-1 543ng/mL (83-456ng/mL), Z-score 2.4, and GH 5.8ng/mL (<= 7.1ng/mL). She wanted a break from medical therapy and discontinued octreotide LAR. She was later started on pegvisomant 15mg but stopped after 10 days due to an allergic reaction and was switched to cabergoline. Cabergoline was up titrated to 3.5mg weekly, still without biochemical control, IGF-1 417ng/mL (103-326ng/mL), Z-score 2.5, GH 7.69ng/mL (0.05-8ng/mL), at which time oral octreotide 20mg twice daily was started and cabergoline decreased to 2.5mg weekly. Oral octreotide was increased to 60mg daily and IGF-1 levels normalized to 294ng/mL (83-456ng/mL), Z-score 1. The second case is a 70 year old female with type 2 diabetes, arthritis, left ventricular hypertrophy, obstructive sleep apnea and colon polyps found to have a 10mm pituitary adenoma with IGF-1 481ng/mL (32-238ng/mL), Z-score 3.1, GH 1.28ng/mL (0.05-8ng/mL). She declined surgical resection and opted for medical management. Oral octreotide 20mg twice daily was started and further increased to 60mg daily IGF-1 went as low as 327ng/mL (28-231ng/mL), Z-score 2.5 and GH 0.4ng/mL (0.05-8ng/mL). The dose was increased to 80 mg daily are lab results are pending. These are the first two published cases describing a novel approach to treating acromegaly in which patients were found to have a biochemical response to de novo oral octreotide either alone or combined with cabergoline. Presentation: Thursday, June 15, 2023

Pioneering time-of-arrival localization with cable-free and battery-free transponders

In traditional underwater acoustic positioning methods, reliance on systems such as Long Baseline (LBL) and Short Baseline (SBL) localization utilize transponders that actively transmit acoustic pulses. These systems are typically powered by cables and often result in constrictive deployment. The adoption of cable-free and battery-free transponders can greatly enhance the flexibility of deployment. This change facilitates large-scale implementation, thereby providing precise positioning services across extensive areas. However, localization with passive transponders faces unique challenges. It has been widely accepted that battery-free nodes are unsuitable for time-of-arrival (ToA) localization. The primary reason is the wakeup delay varies based on location and environment, which introduces an unpredictable offset into the time lapse between the transmitted and received pulses. To overcome this challenge, we model the wakeup delay of passive node, considering the hardware characteristics of the passive node and the multipath acoustic channel. Moreover, we propose a ToA-based localization framework specifically tailored for battery-free transponders. In this paper, we will verify our wakeup delay model and assess the performance of the proposed localization method through experimental results. This new approach marks a significant departure from the existing effort, making localization with passive transponders feasible.

BIM Implementation for Storing, Sharing and Capturing Knowledge in Indonesian Project Construction

BIM as a digital representation of assets has been used to facilitate design, construction, and operation process to form a reliable basis for decisions. While knowledge is part of the company's assets, knowledge will be maintained in the system so that it may be recalled if needed if BIM is used to document, store, and distribute knowledge more easily. This study will determine how BIM adoption supports knowledge storage, knowledge share, and knowledge capture in Indonesian construction projects. Data was obtained by interview and analysed using qualitative method. The results showed that large state-owned construction companies in Indonesia had implemented BIM-based knowledge management to assist organisational knowledge management process, especially in knowledge capture, storage and share on several projects, and reduce knowledge loss due to time lapse. Finding also shows that knowledge created in a project is centralised in one model, and lessons or knowledge can be grouped with BIM user preferences.

Case study: Repowering of ORC system by means of experimental test bench with supercritical carbon dioxide, proposal, and field experience improvements

Although organic Rankine cycles (ORCs) have cornered the small-scale energy harvesting market, the generation capacities produced by sCO2 cycles far exceed those of ORCs, reaching higher powers and efficiencies. This paper analyzes the results of the field tests performed in 2022 at the Grupo Dragón, Nayarit, Mexico, facilities, in which the objective was to validate the operation of the ORC IDEA-10 system with a capacity of up to 10 kWe. The thermodynamic states reached during the test time lapses in which there was full operational stability and with direct loads are analyzed. The results obtained together with proposals for improvement led to compare the performance of ORCs with sCO2 systems for low temperature geothermal sources. The efficiencies of simple sCO2 cycles (5.32%) turned out to be lower than that of ORC at the same temperatures (9.7%), however, the efficiency of the sCO2 cycle improved notably in a regenerative configuration, given the properties of CO2 near its critical point, reaching efficiencies above 25% even at low temperatures compared to conventional ORCs with efficiencies below 10%. Finally, the basis for the implementation of sCO2 in low enthalpy geothermal applications was established, designing an experimental circuit with results obtained in the literature.

Using In-game Analytics to Explore Learning Dynamics of Information Literacy in a Social Media Simulator

The emergence of Game-Based Learning (GBL) strategies to promote critical thinking has generated a growing need for analytical tools able to assess their effectiveness. Current methods typically apply qualitative approaches such as focus groups and survey-based questionnaires evaluating players’ knowledge, skills, and attitudes before and after playing the game; these methods are flexible, and they provide valuable information, yet new methods are needed to improve our understanding of what is happening during a gameplay session.
 The challenge of understanding the internal dynamics of GBL are illustrated by the open debate on gamified disinformation inoculators. These educational tools teach players how to identify disinformation by training them with a small set of fake news displayed within a gaming experience. There is an ongoing debate on what exactly is being learnt with these inoculators as some studies suggest a positive effect while other ones reveal that they promote scepticism instead of resistance against fake news. It is argued that new analytical methods are required to capture the learning process: detailed data collection on gameplay would be extremely useful to identify the most useful traits of Game-Based Learning, while detecting potential limitations or negative effects of this valuable learning resource.
 This work presents a novel framework to assess GBL dynamics grounded on data analytics. The approach uses the potential of the Unity in-game analytics platform to collect detailed data on how players tackle the challenges posed by the game mechanics; this diverse information may include the full set of decisions and interactions of the player as well as additional information such as the number of tries or time lapse between interactions. The behavioural data is then combined with content metadata information to infer general learning dynamics amongst players.
 This analytical framework is applied to a social media simulator included in the video game Julia: A Science Journey. Results suggest that the framework can reveal novel insights including aspects such as the level of engagement of the players, the impact of the type of content on the correct assessment of fake news, and the relation between reading speed and performance.

Influence of scar age, laser type and laser treatment intervals on adult burn scars: A systematic review and meta-analysis.

The study aims to identify whether factors such as time to initiation of laser therapy following scar formation, type of laser used, laser treatment interval and presence of complications influence burn scar outcomes in adults, by meta-analysis of previous studies. A literature search was conducted in May 2022 in seven databases to select studies on the effects of laser therapy in adult hypertrophic burn scars. The study protocol was registered with PROSPERO (CRD42022347836). Eleven studies were included in the meta-analysis, with a total of 491 patients. Laser therapy significantly improved overall VSS/POSAS, vascularity, pliability, pigmentation and scar height of burn scars. Vascularity improvement was greater when laser therapy was performed >12 months (-1.50 [95%CI = -2.58;-0.42], p = 0.01) compared to <12 months after injury (-0.39 [95%CI = -0.68; -0.10], p = 0.01), the same was true for scar height ((-1.36 [95%CI = -2.07; -0.66], p<0.001) vs (-0.56 [95%CI = -0.70; -0.42], p<0.001)). Pulse dye laser (-4.35 [95%CI = -6.83; -1.86], p<0.001) gave a greater reduction in VSS/POSAS scores compared to non-ablative (-1.52 [95%CI = -2.24; -0.83], p<0.001) and ablative lasers (-0.95 [95%CI = -1.31; -0.59], p<0.001). Efficacy of laser therapy is influenced by the time lapse after injury, the type of laser used and the interval between laser treatments. Significant heterogeneity was observed among studies, suggesting the need to explore other factors that may affect scar outcomes.

A pilot study of light exposure as a countermeasure for menstrual phase-dependent neurobehavioral performance impairment in women

ObjectiveTo examine effects of menstrual phase and nighttime light exposure on subjective sleepiness and auditory Psychomotor Vigilance Task performance. MethodsTwenty-nine premenopausal women (12 =Follicular; 17 =Luteal) completed a 6.5-hour nighttime monochromatic light exposure with varying wavelengths (420-620 nm) and irradiances (1.03-14.12 µW/cm2). Subjective sleepiness, reaction time, and attentional lapses were compared between menstrual phases in women with minimal (<33%) or substantial (≥33%) light-induced melatonin suppression. ResultsWhen melatonin was not suppressed, women in the follicular phase had significantly worse reaction time (mean difference=145.1 ms, 95% CI 51.8-238.3, p < .001, Cohen’s D=1.9) and lapses (mean difference=12.9 lapses, 95% CI 4.37-21.41, p < .001, Cohen’s D=1.7) compared to women in the luteal phase. When melatonin was suppressed, women in the follicular phase had significantly better reaction time (mean difference=152.1 ms, 95% CI 43.88-260.3, p < .001, Cohen’s D=1.7) and lapses (mean difference=12.3 lapses, 95% CI 1.14-25.6, p < .01, Cohen’s D=1.6) compared to when melatonin was not suppressed, such that their performance was not different (p > .9) from women in the luteal phase. Subjective sleepiness did not differ by menstrual phase (mean difference=0.6, p > .08) or melatonin suppression (mean difference=0.2, p > .4). ConclusionsNighttime light exposure sufficient to suppress melatonin can also mitigate neurobehavioral performance deficits associated with the follicular phase. Despite the relatively small sample size, these data suggest that nighttime light may be a valuable strategy to help reduce errors and accidents in female shift workers.

Development of the Institute of Criminal Procedural Evidence

The fulfillment of the key function of criminal proceedings – the resolution of the case on the merits – is impossible without criminal procedural knowledge of all the circumstances of the crime committed. The foundation of this activity is criminal procedure and evidence, which is a very complex, multi-level system. The foundation of such a system is evidence. At present, there are serious contradictions in how the sources of evidentiary information, evidence of practice, and proof are interrelated. Collection, verification, evaluation and presentation of evidence, both in theory and in practice, often give rise to non-legal, unfair and unjustified criminal procedural decisions in pre-trial proceedings and in court. Despite the plethora if views on the theory of evidence, the lack of consistency in investigative and judicial practice with regard to the evidence suggests that at present there are a large number of unresolved problems in this field as well as on the legislative level. In this regard, it seems necessary to conduct a study on the historical and legal aspects of the institute of evidence and proof in domestic legislation in order to identify the prerequisites of its origin and patterns of development. The conducted research has theoretical and practical significance. First, it contributes to the development of the topic under discussion. Second, the identified regularities allow us to use them to develop recommendations on improving the current criminal procedural legislation. The author concludes that with lapse of time, the concept of evidence has changed: from a means of substantiating guilt in “evidence-argument” terms to an element of the system of evidence including source, content and procedural form. In addition, the criteria for analyzing the development of evidence law have been formulated.

Focusing on the accumulation of chromatin/chromosomes around nucleoli and optimizing the timing of ICSI to facilitate the rescue in vitro maturation of denuded GV stage oocytes.

This study aims to achieve the methodological improvement of rescue IVM by predicting germinal vesicle breakdown (GVBD) and optimizing the timing of ICSI. Time lapse analysis was performed retrospectively to evaluated the relationship between the presence of AC around the nucleoli and GVBD. To find the optimal timing of ICSI, the time from the initiation of the first polar body extrusion to ICSI were measured, and the rates of fertilization at each point were calculated. The GVBD rate of GV stage oocytes with AC around the nucleoli was significantly higher than that of GV stage oocytes without AC. The GV stageoocytes required more time for nuclear maturation after polar body extrusion than MI oocytes, with GV stageoocytes taking 400-600min from polar body extrusion to the optimal timing of ICSI, while the MI stageoocytes took 200-400min. The GV stage oocytes resulted in the birth of healthy babies with the appropriate timing of ICSI. It was found that GV stageoocytes with AC around nucleoli can initiate GVBD and reach the MII stage with a high rate, and that GV stage oocytes required more time than MI stageoocytes to reach the optimal timing of ICSI. Considering these factors, ART laboratories may employ immature GV stageoocytes in routine ART procedures rather than discarding them.

Management of large furcal defect -1.5 year follow up: A case report

In about 2 -12 % perforation may occur while doing a root canal or post placement. Perforation can be pathological or mechanical. Treatment outcome will depend on several factors size, position, time lapse, sealing ability of the material used. In this case report patient came with furcation defect which was managed with MTA and patient was kept on follow for 1.5 year.

Exploring the males' terminal investment strategy: Impact of the dose of stress and the time lapse between stress and mating

Abstract In the terminal investment strategy, organisms allocate resources to maximize current reproduction when their future reproductive opportunities are uncertain due to a high risk of mortality. However, whether the role of time lapse between stress and reproductive investment (courtship vs. courtship and mating) triggers the terminal investment strategy remains unknown. We examined this hypothesis in Tenebrio molitor using oxidative stress as the stressor. Given that this is the first time that oxidative stress is used to trigger terminal investment, we first conducted mate choice trials where males exposed to 5, 20, 40 or 80 mM of the pro‐oxidant, paraquat (PQ) engaged in courtship behaviour towards the females. Subsequently, we analysed the male mortality against each of these doses. Males exposed to a 5 mM treatment exhibited higher survival rates compared with the control group, whereas males exposed to 80 mM experienced a shorter lifespan. After courtship, no significant differences in mortality were observed between the control group and those treated with 20 or 40 mM of PQ. Notably, only males exposed to 40 mM of PQ were preferred over the control group. In a third experiment, we quantify the survival costs when males courted and mated at varying time intervals after oxidative stress (40 mM). When males were exposed to 40 mM of PQ and mated 3 h later, their mortality rates significantly decreased compared with males exposed to oxidative stress, courted and mated, but 24 h later. We suggest that the interaction of the dose of oxidative stress and the time lapse between courtship and mating may explain opposed results to support either the terminal investment or honest signalling.

Spontaneous α Brain Dynamics Track the Episodic "When".

Across species, neurons track time over the course of seconds to minutes, which may feed the sense of time passing. Here, we asked whether neural signatures of time-tracking could be found in humans. Participants stayed quietly awake for a few minutes while being recorded with magnetoencephalography (MEG). They were unaware they would be asked how long the recording lasted (retrospective time) or instructed beforehand to estimate how long it will last (prospective timing). At rest, rhythmic brain activity is nonstationary and displays bursts of activity in the alpha range (α: 7-14 Hz). When participants were not instructed to attend to time, the relative duration of α bursts linearly predicted individuals' retrospective estimates of how long their quiet wakefulness lasted. The relative duration of α bursts was a better predictor than α power or burst amplitude. No other rhythmic or arrhythmic activity predicted retrospective duration. However, when participants timed prospectively, the relative duration of α bursts failed to predict their duration estimates. Consistent with this, the amount of α bursts was discriminant between prospective and retrospective timing. Last, with a control experiment, we demonstrate that the relation between α bursts and retrospective time is preserved even when participants are engaged in a visual counting task. Thus, at the time scale of minutes, we report that the relative time of spontaneous α burstiness predicts conscious retrospective time. We conclude that in the absence of overt attention to time, α bursts embody discrete states of awareness constitutive of episodic timing.SIGNIFICANCE STATEMENT The feeling that time passes is a core component of consciousness and episodic memory. A century ago, brain rhythms called "α" were hypothesized to embody an internal clock. However, rhythmic brain activity is nonstationary and displays on-and-off oscillatory bursts, which would serve irregular ticks to the hypothetical clock. Here, we discovered that in a given lapse of time, the relative bursting time of α rhythms is a good indicator of how much time an individual will report to have elapsed. Remarkably, this relation only holds true when the individual does not attend to time and vanishes when attending to it. Our observations suggest that at the scale of minutes, α brain activity tracks episodic time.

Low levels of mouse sperm chromatin fragmentation delay embryo development.

We previously demonstrated that MnCl2 induces double-stranded DNA breaks in sperm in a process that we term as sperm chromatin fragmentation. Here, we tested if the levels of double-stranded DNA breaks were corelated to the concentration of MnCl2, and we compared this to another agent that causes single-stranded DNA breaks, H2O2. We found that both methods have the advantage of inducing DNA breaks in a concentration-dependent manner. Mouse sperm were treated with varying concentrations of either H2O2 or MnCl2, and the DNA damage was assessed by pulse-field gel electrophoresis, and the alkaline and neutral comet assays. Oocytes were injected with either treated sperm and the resulting embryos analyzed with an embryoscope to detect subtle changes in embryonic development. We confirmed that H2O2 treatment induced primarily single-stranded DNA breaks and MnCl2 induced primarily double-stranded DNA breaks, indicating different mechanisms of damage. These sperm were injected into oocytes, and the development of the resulting embryos followed with an embryoscope equipped with time lapse recording. We found that aberrations in early embryonic development by day 2 with even the lowest levels of DNA damage and that the levels of embryonic aberrations correlated to the concentration of either H2O2 or MnCl2. Low levels of H2O2 caused significantly more aberrations in embryonic development than low levels of MnCl2 even though the levels of DNA damage as measured by comet assays were similar. These data demonstrate that even low levels of sperm DNA damage cause delays and arrests in embryonic development.

Examining Student Readiness for Upper Division Coursework

This study examines student readiness for an upper division finance course by examining performance on topics that form the prerequisite knowledge. The data consist of assessment results from a multiple-choice questionnaire given to students at the beginning of the course. Regression variables include test results, location of prerequisite course, and months lapsed since completion of prerequisite course. The prerequisite locations are traceable to three institutions and include one four-year institution and two, two-year institutions. Overall mean student performance is low: 3.93/6.00, 65.5%, native students outperform transfer students by an average of 10%. For the total sample, time lapse is not significant, but interactive terms are negative and significant for students at two-year institutions indicating the possibility of a “forgetting variable.” A case is made for identifying gaps and improving student readiness for all upper division finance course work requiring prerequisite knowledge.

Concordance of ASCL1, NEUROD1 and POU2F3 transcription factor-based subtype assignment in paired tumour samples from small cell lung carcinoma.

Small cell lung carcinoma (SCLC) can be classified into transcription factor-based subtypes (ASCL1, NeuroD1, POU2F3). While in-vitro studies suggest intratumoral heterogeneity in the expression of these markers, how SCLC subtypes vary over time and among locations in patients remains unclear. We searched a consecutive series of patients at our institution in 2006-22 for those with greater than one available formalin-fixed paraffin-embedded SCLC sample in multiple sites and/or time-points. Immunohistochemistry for ASCL1, NeuroD1 and POU2F3 was performed and evaluated using H-scores, with subtype assigned based on the positive marker (H-score threshold >10) with the highest H-score. The 179 samples (75, lung; 51, lymph nodes; 53, non-nodal metastases) from 84 patients (74 with two, 10 with more than two samples) included 98 (54.7%) ASCL1-dominant, 47 (26.3%) NeuroD1-dominant, 15 (8.4%) POU2F3-dominant, 17 (9.5%) triple-negative and two (1.1%) ASCL1/NeuroD1 co-dominant samples. NeuroD1-dominant subtype was enriched in non-lung locations. Subtype concordance from pairwise comparison was 71.4% overall and 89.7% after accounting for ASCL1/NeuroD1-dual expressors and technical factors including <500 cells/slide, H-score thresholds and sample decalcification. No significant difference in subtype concordance was noted with a longer time lapse or with extrathoracic versus intrathoracic samples in this cohort. After accounting for technical factors, transcription factor-based subtyping was discordant among multiple SCLC samples in ~10% of patients, regardless of sample locations and time lapse. Our findings highlighted the spatiotemporal heterogeneity of SCLC in clinical samples and potential challenges, including technical and biological factors, that might limit concordance in SCLC transcription factor-based subtyping.

(Invited) Design and Modeling of Resistive Switching Devices for Neuromorphic Applications

Resistive switching devices are a critical component for the realization of computational systems that mimic biological neural systems. In biological systems, connection weights between the neurons are dependent on the time lapse between the neurons’ action potentials. Resistive switching devices (memristors) with multiple conductance states can mimic this biological spike-time-dependent plasticity (STDP) behaviour, with multiple conductance states being analogous to different synaptic weights. Additionally, memristors are one of the contenders as storage elements in non-volatile memories. The change in conductance in memristors can be broadly attributed to vacancy migration inside the switching layer (valence change memory) or the formation of metallic filaments inside the switching layer (electrochemical metallization).Electrochemical metallization-based memristors with vertical transport and small inter-electrode distances have been reported recently. Their device characteristics exhibit multiple conductance states with relatively low switching voltages, which makes them well-suited for low-power neuromorphic applications. Our work models the transport in these memristors, focusing on explaining and capturing their current-voltage characteristics. Our model also captures the switching dynamics (with an emphasis on estimating switching energies and delays) and explains the experimentally observed STDP behaviour in these devices. We have proposed models for filament growth and dissolution along one dimension (axial) and two dimensions (axial and radial). The simulation results obtained using our model (and implemented in Verilog-A) have been validated with experimental data from multiple sources. Our work demonstrates the flexibility of including different transport mechanisms in a unified framework.We have characterized valence change memory (VCM) memristors with HfO2 and HfZrO2 as switching layers. They exhibit bipolar switching, negative differential resistance, multiple conductance states, and STDP behaviour, which have been analyzed. We have also modeled the transport in these VCM-based memristors, and simulated the I-V and dynamic switching characteristics, and STDP behaviour in these devices. We have simulated arrays of, both, ECM and VCM devices using the proposed models, and tried to demonstrate a typical pattern classification problem using in-memory computation. We believe that our models provide useful insight into the design of memristors for neuromorphic and memory applications.

Recurrent thoracic air leak syndrome in patients affected by pulmonary graft-versus-host disease: Surgical strategies and outcome.

Thoracic air leak syndrome (TALS) is a complication related to chronic pulmonary graft-versus-host disease (pGvHD) that affects approximately 0.83%-3.08% patients after allogenic hematopoietic stem cell transplant. Such complication is defined as the occurrence of any form of air leak in the thorax, including spontaneous pneumomediastinum or pneumopericardium, subcutaneous emphysema, interstitial emphysema and pneumothorax and has a negative impact on post-transplant survival. The aim of the present study is to describe a single-center experience in the surgical management of recurrent TALS in adolescents and young adults and its outcome. We retrospectively reviewed the clinical notes of patients with previous allogenic hematopoietic stem cell transplant who underwent surgical procedures for recurrent TALS from January 2016 until March 2021. We analyzed clinical data, number of episodes of thoracic air leak, surgical procedures and relative outcome. In the examined period, four patients, aged 16-25 years, underwent surgical procedures for TALS, including thoracostomy tube placement, thoracoscopic pleurodesis and thoracotomy. All the patients had been diagnosed with pGvHD before the onset of TALS, with a mean time lapse of 276 days (range 42-513). These patients experienced on average 4.5 air leak episodes (range 3-6). All the patients experienced at least two episodes before surgery. One patient underwent emergency tube thoracostomy only, three patients underwent thoracoscopic pleurodesis and two patients underwent thoracotomy. After surgery, patients were free from air leak symptoms for a mean time of 176 days (range 25-477). Pulmonary function progressively deteriorated, and all the patients eventually died because of respiratory failure after a mean time of 483 days (range 127-1045) after the first episode of air leak. Surgery provides temporary relief to symptoms related to TALS but has limited effects on the underlying pathophysiologic process. The development of TALS in a sign of progressive pulmonary function worsening and is associated with high risk of respiratory failure and mortality.