Hybrid organic:inorganic materials composed of semiconductor nanocrystals functionalized with acene ligands have recently emerged as a promising platform for photon upconversion. Infrared light ...absorbed by a nanocrystal excites charge carriers that can pass to surface-bound acenes, forming triplet excitons capable of fusing to produce visible radiation. To fully realize this scheme, energy transfer between nanocrystals and acenes must occur with high efficiency, yet the mechanism of this process remains poorly understood. To improve our knowledge of the fundamental steps involved in nanoparticle:acene energy transfer, we used ultrafast transient absorption to investigate excited electronic dynamics of PbS nanocrystals chemically functionalized with 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) ligands. We find photoexcitation of PbS does not lead to direct triplet energy transfer to surface-bound TIPS-pentacene molecules but rather to the formation of an intermediate state within 40 ps. This intermediate persists for ∼100 ns before evolving to produce TIPS-pentacene triplet excitons. Analysis of transient absorption lineshapes suggests this intermediate corresponds to charge carriers localized at the PbS nanocrystal surface. This hypothesis is supported by constrained DFT calculations that find a large number of spin-triplet states at PbS NC surfaces. Though some of these states can facilitate triplet transfer, others serve as traps that hinder it. Our results highlight that nanocrystal surfaces play an active role in mediating energy transfer to bound acene ligands and must be considered when optimizing composite NC-based materials for photon upconversion, photocatalysis, and other optoelectronic applications.
Conflict between genes inherited from the mother (matrigenes) and the father (patrigenes) is predicted to arise during social interactions among offspring if these genes are not evenly distributed ...among offspring genotypes. This intragenomic conflict drives parent-specific transcription patterns in offspring resulting from parent-specific epigenetic modifications. Previous tests of the kinship theory of intragenomic conflict in honey bees (Apis mellifera) provided evidence in support of theoretical predictions for variation in worker reproduction, which is associated with extreme variation in morphology and behavior. However, more subtle behaviors - such as aggression - have not been extensively studied. Additionally, the canonical epigenetic mark (DNA methylation) associated with parent-specific transcription in plant and mammalian model species does not appear to play the same role as in honey bees, and thus the molecular mechanisms underlying intragenomic conflict in this species is an open area of investigation. Here, we examined the role of intragenomic conflict in shaping aggression in honey bee workers through a reciprocal cross design and Oxford Nanopore direct RNA sequencing. We attempted to probe the underlying regulatory basis of this conflict through analyses of parent-specific RNA m6A and alternative splicing patterns. We report evidence that intragenomic conflict occurs in the context of honey bee aggression, with increased paternal and maternal allele-biased transcription in aggressive compared to non-aggressive bees, and higher paternal allele-biased transcription overall. However, we found no evidence to suggest that RNA m6A or alternative splicing mediate intragenomic conflict in this species.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Behavioural variation is essential for animals to adapt to different social and environmental conditions. The Kinship Theory of Intragenomic Conflict (KTIC) predicts that parent‐specific ...alleles can support different behavioural strategies to maximize allele fitness. Previous studies, including in honey bees (
Apis mellifera
), supported predictions of the KTIC for parent‐specific alleles to promote selfish behaviour. Here, we test the KTIC prediction that for altruism‐promoting genes (i.e. those that promote behaviours that support the reproductive fitness of kin), the allele with the higher altruism optimum should be selected to be expressed while the other is silenced. In honey bee colonies, workers act altruistically when tending to the queen by performing a ‘retinue’ behaviour, distributing the queen's mandibular pheromone (QMP) throughout the hive. Workers exposed to QMP do not activate their ovaries, ensuring they care for the queen's brood instead of competing to lay unfertilized eggs. Due to the haplodiploid genetics of honey bees, the KTIC predicts that response to QMP is favoured by the maternal genome. We report evidence for parent‐of‐origin effects on the retinue response behaviour, ovarian development and gene expression in brains of worker honey bees exposed to QMP, consistent with the KTIC. Additionally, we show enrichment for genes with parent‐of‐origin expression bias within gene regulatory networks associated with variation in bees' response to QMP. Our study demonstrates that intragenomic conflict can shape diverse social behaviours and influence expression patterns of single genes as well as gene networks.
Researchers have long sought to use surface ligands to enhance energy migration in nanocrystal solids by decreasing the physical separation between nanocrystals and strengthening their electronic ...coupling. Exciton-delocalizing ligands, which possess frontier molecular orbitals that strongly mix with nanocrystal band-edge states, are well-suited for this role because they can facilitate carrier-wave function extension beyond the nanocrystal core, reducing barriers for energy transfer. This report details the use of the exciton-delocalizing ligand phenyldithiocarbamate (PDTC) to tune the transport rate and diffusion length of excitons in CdSe nanocrystal solids. A film composed of oleate-terminated CdSe nanocrystals is subjected to a solid-state ligand exchange to replace oleate with PDTC. Exciton migration in the films is subsequently investigated by femtosecond transient absorption. Our experiments indicate that the treatment of nanocrystal films with PDTC leads to rapid (∼400 fs) downhill energy migration (∼80 meV), while no such migration occurs in oleate-capped films. Kinetic Monte Carlo simulations allow us to extract both rates and length scales for exciton diffusion in PDTC-treated films. These simulations reproduce dynamics observed in transient absorption measurements over a range of temperatures and confirm excitons hop via a Miller–Abrahams mechanism. Importantly, our experiments and simulations show PDTC treatment increases the exciton hopping rate to 200 fs, an improvement of 5 orders of magnitude relative to oleate-capped films. This exciton hopping rate stands as one of the fastest determined for CdSe solids. The facile, room-temperature processing and improved transport properties offered by the solid-state exchange of exciton-delocalizing ligands show they offer promise for the construction of strongly coupled nanocrystal arrays.
Process Technology Variation Kuhn, K. J.; Giles, M. D.; Becher, D. ...
IEEE transactions on electron devices,
2011-Aug., 2011-08-00, 20110801, Letnik:
58, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Moore's law technology scaling has improved performance by five orders of magnitude in the last four decades. As advanced technologies continue the pursuit of Moore's law, a variety of challenges ...will need to be overcome. One of these challenges is the management of process variation. This paper discusses the importance of process variation in modern transistor technology, reviews front-end variation sources, presents device and circuit variation measurement techniques, including circuit and memory data from the 32-nm node, and compares recent intrinsic transistor variation performance from the literature.
Akkermansia muciniphila and Desulfovibrio spp. are commensal microbes colonising the mucus gel layer of the colon. Both species have the capacity to utilise colonic mucin as a substrate. A. ...muciniphila degrades colonic mucin, while Desulfovibrio spp. metabolise the sulfate moiety of sulfated mucins. Altered abundances of these microorganisms have been reported in ulcerative colitis (UC). However their capacity to bind to human colonic mucin, and whether this binding capacity is affected by changes in mucin associated with UC, remain to be defined.
Mucin was isolated from resected colon from control patients undergoing resection for colonic cancer (n = 7) and patients undergoing resection for UC (n = 5). Isolated mucin was purified and printed onto mucin microarrays. Binding of reference strains and three clinical isolates of A. muciniphila and Desulfovibrio spp. to purified mucin was investigated.
Both A. muciniphila and Desulfovibro spp. bound to mucin. The reference strain and all clinical isolates of A. muciniphila showed increased binding capacity for UC mucin (p < .005). The Desulfovibrio reference strain showed increased affinity for UC mucin. The mucin binding profiles of clinical isolates of Desulfovibrio spp. were specific to each isolate. Two isolates showed no difference in binding. One UC isolate bound with increased affinity to UC mucin (p < .005).
These preliminary data suggest that differences exist in the mucin binding capacity of isolates of A. muciniphila and Desulfovibrio spp. This study highlights the mucin microarray platform as a means of studying the ability of bacteria to interact with colonic mucin in health and disease.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We integrate theory and research about individuals' responses to failures and develop a model in which occupational progress failures precipitate ruminative processes that limit the extent to which ...individuals subsequently act as informal leaders. Our first study, an experiment with a sample of advanced accounting students, found that manipulating poor performance on a simulated certification test promoted ruminative thoughts about the test, which were negatively related to peer ratings of informal leadership behavior during a subsequent task. A separate field study using a regression discontinuity design in a 14-week military training program found that failure to pass the required physical fitness examination early in group formation influenced psychosomatic symptoms-an indirect measure of sustained rumination-and consequently hindered enactment of informal leadership behavior. We also theorized and found that neuroticism enhanced the positive effect of failure on rumination in Study 1 and psychosomatic symptoms in Study 2. We discuss the implications for developing theories concerning how disruptive personal events may interfere with employees' engaging in informal leadership behavior.
Helminth parasites represent a significant threat to the health of human and animal populations, and there is a growing need for tools to treat, diagnose, and prevent these infections. Recent work ...has turned to the gut microbiome as a utilitarian agent in this regard; components of the microbiome may interact with parasites to influence their success in the gut, meaning that the microbiome may encode new anthelmintic drugs. Moreover, parasite infections may restructure the microbiome's composition in consistent ways, implying that the microbiome may be useful for diagnosing infection. The innovation of these utilities requires foundational knowledge about how parasitic infection, as well as its ultimate success in the gut and impact on the host, relates to the gut microbiome. In particular, we currently possess limited insight into how the microbiome, host pathology, and parasite burden covary during infection. Identifying interactions between these parameters may uncover novel putative methods of disrupting parasite success.
To identify interactions between parasite success and the microbiome, we quantified longitudinal associations between an intestinal helminth of zebrafish, Pseudocapillaria tomentosa, and the gut microbiome in 210 4-month-old 5D line zebrafish. Parasite burden and parasite-associated pathology varied in severity throughout the experiment in parasite-exposed fish, with intestinal pathologic changes becoming severe at late time points. Parasite exposure, burden, and intestinal lesions were correlated with gut microbial diversity. Robust generalized linear regression identified several individual taxa whose abundance predicted parasite burden, suggesting that gut microbiota may influence P. tomentosa success. Numerous associations between taxon abundance, burden, and gut pathologic changes were also observed, indicating that the magnitude of microbiome disruption during infection varies with infection severity. Finally, a random forest classifier accurately predicted a fish's exposure to the parasite based on the abundance of gut phylotypes, which underscores the potential for using the gut microbiome to diagnose intestinal parasite infection.
These experiments demonstrate that P. tomentosa infection disrupts zebrafish gut microbiome composition and identifies potential interactions between the gut microbiota and parasite success. The microbiome may also provide a diagnostic that would enable non-destructive passive sampling for P. tomentosa and other intestinal pathogens in zebrafish facilities.
Background There is increasing attention on immunizations by obstetrician-gynecologists and a need to improve vaccination rates for all women. Objective To evaluate the effect of a multimodal ...intervention on rates of immunization with tetanus, diphtheria, and acellular pertussis (Tdap); human papillomavirus (HPV); and influenza in outpatient obstetrics and gynecology clinics. Study Design Immunization rates at 2 clinics were compared pre- and post-implementation of multiple interventions at a public integrated health-care system. Study interventions began on June 6, 2012 and concluded on May 31, 2014; the preimplementation time period used was June 6, 2010 to June 5, 2012. Interventions included stocking of immunizations in clinics, revision and expansion of standing orders, creation of a reminder/recall program, identification of an immunization champion to give direct provider feedback, expansion of a payment assistance program, and staff education. All women aged 15 and older who made a clinic visit during influenza season were included in the influenza cohort; women who delivered an infant during the study time period and had at least 1 prenatal visit within 9 months preceding delivery were included in the Tdap cohort; each clinic visit by a nonpregnant woman aged 15–26 years was assessed and included in the HPV analysis as an eligible visit if the patient was lacking any of the 3 HPV vaccines in the series. The primary outcome was receipt of influenza and Tdap vaccine per current American College of Obstetricians and Gynecologists guidelines and receipt of HPV vaccine during eligible visits. Influenza and Tdap were assessed with overall coverage rates at the institutional level, and HPV was assessed at the visit level by captured opportunities. All analyses included generalized estimating equations and the primary outcome was assessed with time as a covariate in all models. Results A total of 19,409 observations were included in the influenza cohort (10,231 pre- and 9178 post-intervention), 2741 in the Tdap cohort (1248 pre- and 1493 post-intervention), and 12,443 in the HPV cohort (7966 pre- and 4477 post-intervention). Our population was largely Hispanic, English-speaking, and publicly insured. The rate of influenza vaccination increased from 35.4% pre-intervention to 46.0% post-intervention ( P < .001). The overall rate for Tdap vaccination increased from 87.6% pre-intervention to 94.5% post-intervention until the recommendation to vaccinate during each pregnancy was implemented (z = 4.58, P < .0001). The average Tdap up-to-date rate after that recommendation was 75.0% (z = -5.77, P < .0001). The overall rate of HPV vaccination with an eligible visit increased from 7.1% before to 23.7% after the intervention. Conclusion Using evidence-based practices largely established in other settings, our intervention was associated with increased rates of influenza, Tdap, and HPV vaccination in outpatient underserved obstetrics and gynecology clinics. Integrating such evidence-based practices into routine obstetrics and gynecology care could positively impact preventive health for many women.
Rationale
Individuals vary considerably in the extent to which they attribute incentive salience to food-associated cues.
Objectives
We asked whether individuals prone to attribute incentive salience ...to a food cue are also prone to attribute incentive properties to a stimulus associated with a drug of abuse—cocaine.
Methods
We first identified those rats that attributed incentive salience to a food cue by quantifying the extent to which they came to approach and engage a food cue. We then used a conditioned place preference procedure to pair an injection of 10 mg/kg cocaine (i.p.) with one distinct floor texture (grid or holes) and saline with another. Following 8 days of conditioning, each rat was given a saline injection and placed into a chamber that had both floors present. We measured the time spent on each floor, and also 50-kHz ultrasonic vocalizations, which have been associated with positive affective states.
Results
Rats that vigorously engaged the food cue (“sign trackers”) expressed a preference for the cocaine-paired floor compared to those that did not (“goal trackers”). In addition, sign trackers made substantially more frequency-modulated 50-kHz vocalizations when injected with cocaine and when later exposed to the cocaine cue.
Conclusions
Rats prone to attribute incentive salience to a food cue are also prone to attribute incentive motivational properties to a tactile cue associated with cocaine. We suggest that individuals prone to attribute incentive salience to reward cues will have difficulty resisting them and, therefore, may be especially vulnerable to develop impulse control disorders, including addiction.
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