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The concentration of radiocarbon (14C) differs between ocean and atmosphere. Radiocarbon determinations from samples which obtained their 14C in the marine environment therefore need a marine-specific calibration curve and cannot be calibrated directly against the atmospheric-based IntCal20 curve. This paper presents Marine20, an update to the internationally agreed marine radiocarbon age calibration curve that provides a non-polar global-average marine record of radiocarbon from 0–55 cal kBP and serves as a baseline for regional oceanic variation. Marine20 is intended for calibration of marine radiocarbon samples from non-polar regions; it is not suitable for calibration in polar regions where variability in sea ice extent, ocean upwelling and air-sea gas exchange may have caused larger changes to concentrations of marine radiocarbon. The Marine20 curve is based upon 500 simulations with an ocean/atmosphere/biosphere box-model of the global carbon cycle that has been forced by posterior realizations of our Northern Hemispheric atmospheric IntCal20 14C curve and reconstructed changes in CO2 obtained from ice core data. These forcings enable us to incorporate carbon cycle dynamics and temporal changes in the atmospheric 14C level. The box-model simulations of the global-average marine radiocarbon reservoir age are similar to those of a more complex three-dimensional ocean general circulation model. However, simplicity and speed of the box model allow us to use a Monte Carlo approach to rigorously propagate the uncertainty in both the historic concentration of atmospheric 14C and other key parameters of the carbon cycle through to our final Marine20 calibration curve. This robust propagation of uncertainty is fundamental to providing reliable precision for the radiocarbon age calibration of marine based samples. We make a first step towards deconvolving the contributions of different processes to the total uncertainty; discuss the main differences of Marine20 from the previous age calibration curve Marine13; and identify the limitations of our approach together with key areas for further work. The updated values for ΔR, the regional marine radiocarbon reservoir age corrections required to calibrate against Marine20, can be found at the data base http://calib.org/marine/.
Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.
Prolonged survival of SARS-CoV-2 on environmental surfaces and personal protective equipment may lead to these surfaces transmitting disease to others. This article reports the effectiveness of a pulsed xenon ultraviolet disinfection system in reducing the load of SARS-CoV-2 on hard surfaces and N95 respirators.
Chamber slides and N95 respirator material were directly inoculated with SARS-CoV-2 and exposed to different durations of pulsed xenon ultraviolet disinfection.
For hard surfaces, disinfection for 1, 2, and 5 minutes resulted in 3·53 Log10, >4·54 Log10, and >4·12 Log10 reductions in viral load, respectively. For N95 respirators, disinfection for 5 minutes resulted in >4·79 Log10 reduction in viral load. We found that pulsed xenon ultraviolet significantly reduces SARS-CoV-2 on hard surfaces and N95 respirators.
With the potential to rapidly disinfectant environmental surfaces and N95 respirators, pulsed xenon ultraviolet devices are a promising technology for the reduction of environmental and personal protective equipment bioburden and to enhance both healthcare worker and patient safety by reducing the risk of exposure to SARS-CoV-2.
Heavy alcohol consumption is associated with poorer cognitive function in older adults. Although understudied in middle-aged adults, the relationship between alcohol and cognition may also be influenced by genetics such as the apolipoprotein (ApoE) ε4 allele, a risk factor for Alzheimer’s disease. We examined the relationship between alcohol consumption, ApoE genotype, and cognition in middle-aged adults and hypothesized that light and/or moderate drinkers (≤2 drinks per day) would show better cognitive performance than heavy drinkers or non-drinkers. Additionally, we hypothesized that the association between alcohol use and cognitive function would differ by ApoE genotype (ε4+ vs. ε4−).
Participants were 1266 men from the Vietnam Era Twin Study of Aging (VETSA; M age = 56; range 51–60) who completed a neuropsychological battery assessing seven cognitive abilities: general cognitive ability (GCA), episodic memory, processing speed, executive function, abstract reasoning, verbal fluency, and visuospatial ability. Alcohol consumption was categorized into five groups: never, former, light, moderate, and heavy.
In fully adjusted models, there was no significant main effect of alcohol consumption on cognitive functions. However, there was a significant interaction between alcohol consumption and ApoE ε4 status for GCA and episodic memory, such that the relationship of alcohol consumption and cognition was stronger in ε4 carriers. The ε4+ heavy drinking subgroup had the poorest GCA and episodic memory.
Presence of the ε4 allele may increase vulnerability to the deleterious effects of heavy alcohol consumption. Beneficial effects of light or moderate alcohol consumption were not observed.
Intensified cover cropping practices are increasingly viewed as an herbicide resistance management tool but clear distinction between reactive and proactive resistance management performance targets is needed. We evaluated two proactive performance targets for integrating cover cropping tactics, including (1) facilitation of reduced herbicide inputs, and (2) reduced herbicide selection pressure. We conducted corn (Zea mays L.) and soybean [Glycine max (L.) Merr] field experiments in Pennsylvania and Delaware using synthetic weed seedbanks of horseweed [Conyza canadensis (L.) Cronquist] and smooth pigweed (Amaranthus hybridus L.) to assess winter- and summer- annual population dynamics, respectively. The effect of alternative cover crops was evaluated across a range of herbicide inputs. Cover crop biomass production ranged from 2,000 to 8,500 kg ha-1 in corn and 3,000 to 5,500 kg ha-1 in soybean. Experimental results demonstrated that herbicide-based tactics were the primary drivers of total weed biomass production with cover cropping tactics providing an additive weed suppression benefit. Substitution of cover crops for PRE or POST herbicide programs did not reduce total weed control levels or cash crop yields but did result in lower net returns due to higher input costs. Cover cropping tactics significantly reduced C. canadensis populations in three of four cover crop treatments and decreased the number of large rosettes (> 7.6 cm diameter) at the time of pre-plant herbicide exposure. Substitution of cover crops for PRE herbicides resulted in increased selection pressure on POST herbicides, but reduced the number of large individuals (> 10 cm) at POST applications. Collectively, our findings suggest that cover crops can reduce the intensity of selection pressure on POST herbicides but the magnitude of the effect varies based on weed life-history traits. Additional work is needed to describe proactive resistance management concepts and performance targets for integrating cover crops so producers can apply these concepts in site-specific, within-field management practices.
Addition of fats to the diets of ruminants has long been known to result in a reduction in enteric methane emissions. Tannins have also been used to reduce methane emissions but with mixed success. However, the effect of feeding fat in combination with tannin is unknown. Eight ruminally cannulated Holstein-Friesian cows were fed four diets in a double Latin-square, full crossover sequence. The treatments were 800 ml/day of water (CON), 800 g/day of cottonseed oil, 400 g/day of tannin, and 800 g/day of cottonseed oil and 400 g/day of tannin in combination (fat- and tannin-supplemented diet). Methane emissions were measured using open-circuit respiration chambers. Intake of basal diets was not different between treatments. Cows fed cottonseed oil had greater milk yield (34.9 kg/day) than those fed CON (32.3 kg/day), but the reduced concentration of milk fat meant there was no difference in energy-corrected milk between treatments. Methane yield was reduced when either cottonseed oil (14%) or tannin (11%) was added directly to the rumen, and their effect was additive when given in combination (20% reduction). The mechanism of the anti-methanogenic effect remains unclear but both fat and tannin appear to cause a reduction in fermentation in general rather than cause a change in the type of fermentation.
Although trauma-focused cognitive behavior therapy (TF-CBT) is the frontline treatment for post-traumatic stress disorder (PTSD), one-third of patients are treatment non-responders. To identify neural markers of treatment response to TF-CBT when participants are reappraising aversive material.
This study assessed PTSD patients (n = 37) prior to TF-CBT during functional magnetic brain resonance imaging (fMRI) when they reappraised or watched traumatic images. Patients then underwent nine sessions of TF-CBT, and were then assessed for symptom severity on the Clinician-Administered PTSD Scale. FMRI responses for cognitive reappraisal and emotional reactivity contrasts of traumatic images were correlated with the reduction of PTSD severity from pretreatment to post-treatment.
Symptom improvement was associated with decreased activation of the left amygdala during reappraisal, but increased activation of bilateral amygdala and hippocampus during emotional reactivity prior to treatment. Lower connectivity of the left amygdala to the subgenual anterior cingulate cortex, pregenual anterior cingulate cortex, and right insula, and that between the left hippocampus and right amygdala were also associated with symptom improvement.
These findings provide evidence that optimal treatment response to TF-CBT involves the capacity to engage emotional networks during emotional processing, and also to reduce the engagement of these networks when down-regulating emotions.
Bipartite networks represent pairwise relationships between nodes belonging to two distinct classes. While established methods exist for analyzing unipartite networks, those for bipartite network analysis are somewhat obscure and relatively less developed. Community detection in such instances is frequently approached by first projecting the network onto a unipartite network, a method where edges between node classes are encoded as edges within one class. Here we test seven different projection schemes by assessing the performance of community detection on both: (i) a real-world dataset from social media and (ii) an ensemble of artificial networks with prescribed community structure. A number of performance and accuracy issues become apparent from the experimental findings, especially in the case of long-tailed degree distributions. Of the methods tested, the “hyperbolic” projection scheme alleviates most of these difficulties and is thus the most robust scheme of those tested. We conclude that any interpretation of community detection algorithm performance on projected networks must be done with care as certain network configurations require strong community preference for the bipartite structure to be reflected in the unipartite communities. Our results have implications for the analysis of detected community structure in projected unipartite networks.
Object working memory performance is abnormal in the early stages of schizophrenia. Such tasks recruit frontal and temporal cortices, possible sites of progressive change over the early illness course. We wanted to clarify if functional changes can be detected in the early stages of schizophrenia, to identify their anatomical location and their relationship to the stage of illness using a functional object working memory task in which the length of memory delay was manipulated.
40 subjects contributed: 10 first episode psychosis (FEp) patients, 16 with an at risk mental state (ARMS) and 14 healthy controls. We collected functional MRI data while the subjects performed a version of the delayed matching to sample (DMTS) task from the Cambridge Automated Neuropsychological Test Battery (CANTAB).
Behaviourally there was a trend to a group by delay interaction, the two patient groups making more errors at longer memory delays. At successful recognition a main effect of group was detected in the medial temporal lobe bilaterally, while a main effect of delay was detected in the left medial temporal lobe. At each length of memory delay the patient groups showed consistently greater activation of medial temporal regions when performing the task accurately.
Both ARMS & FEp groups showed greater activation than controls in the medial temporal cortex across all lengths of memory delay. These differences were not related to poorer task performance, but suggest an inefficiency mechanism that may correlate with the vulnerability to psychosis rather than pychosis per se.
Dysfunctional impulsivity reflects ‘recklessness without deliberation and evaluation of consequences’ and has negative consequences whereas functional impulsivity reflects ‘rapid responding to situational demands in order to maximise one's circumstances’ and often has positive consequences (1).
To examine the functional brain basis of dysfunctional impulsivity in healthy people and in people with schizophrenia.
Thirteen healthy controls and 21 schizophrenia patients (10/21 with serious repetitive violence) underwent fMRI during a Go/ NoGo task. Dysfunctional impulsivity was indexed using the Impulsiveness subscale and functional impulsivity using the Venturesomeness subscale of the Impulsiveness-Venturesomeness-Empathy questionnaire (2).
Violent patients had elevated Impulsiveness scores relative to non-violent patients and controls. Impulsiveness did not correlate significantly with task performance in healthy controls or patients. Impulsiveness, but not Venturesomeness, scores correlated during the NoGO condition with lower activity in the anterior cingulate (AC) in controls, and lower inferior temporal and hippocampal activity in patients.
These findings accord with previously reported associations between reduced hippocampal volume and dysfunctional impulsivity in schizophrenia (3) and, combined with our earlier observations of reduced AC activation during a working memory task in violent antisocial individuals (4), suggest that the influence of dysfunctional impulsivity in antisocial and criminal behaviour is mediated via deficient (inhibitory) functions of the AC and hippocampus.
The functional Catechol-O-methyltransferase (COMT Val 108/158 Met) polymorphism has been shown to have an impact on tasks of executive function, memory and attention and recently, tasks with an affective component. As estrogen may downregulate COMT, we were interested in the effect of gender, COMT genotype and the interaction between these factors on brain activations during an affective processing task. We used functional MRI to record brain activations from 74 healthy subjects who engaged in a facial affect recognition task; subjects viewed and identified fearful faces compared to neutral faces. We found a significant effect of gender on brain activations in the left amygdala and right superior temporal gyrus, where females demonstrated increased activations over males. Within these regions, female val/val carriers showed greater activity compared to met/met carriers, while male participants with a met/met allele showed greater deactivations compared to val/val carriers. There was no main effect of the COMT polymorphism, gender or genotype by gender interaction on task performance. We propose that the observed effects of gender and COMT allele on brain activations arise from differences in dopamine levels in these groups and that the gender differences and gender genotype interaction may be due to the downregulation of COMT by estrogen.
Neurocognitive and functional neuroimaging studies point to frontal lobe abnormalities in schizophrenia. Molecular and behavioural genetic studies suggest that the frontal lobe is under significant genetic influence. We carried out structural magnetic resonance imaging (MRI) of the frontal lobe in monozygotic (MZ) twins concordant or discordant for schizophrenia and healthy MZ control twins.
The sample comprised 21 concordant pairs, 17 discordant affected and 18 discordant unaffected twins from 19 discordant pairs, and 27 control pairs. Groups were matched on sociodemographic variables. Patient groups (concordant, discordant affected) did not differ on clinical variables. Volumes of superior, middle, inferior and orbital frontal gyri were calculated using the Cavalieri principle on the basis of manual tracing of anatomic boundaries. Group differences were investigated covarying for whole-brain volume, gender and age.
Results for superior frontal gyrus showed that twins with schizophrenia (i.e. concordant twins and discordant affected twins) had reduced volume compared to twins without schizophrenia (i.e. discordant unaffected and control twins), indicating an effect of illness. For middle and orbital frontal gyrus, concordant (but not discordant affected) twins differed from non-schizophrenic twins. There were no group differences in inferior frontal gyrus volume.
These findings suggest that volume reductions in the superior frontal gyrus are associated with a diagnosis of schizophrenia (in the presence or absence of a co-twin with schizophrenia). On the other hand, volume reductions in middle and orbital frontal gyri are seen only in concordant pairs, perhaps reflecting the increased genetic vulnerability in this group.
There is increasing evidence for a neurobiological basis of antisocial personality disorder (ASPD), includinggenetic liability, aberrant serotonergic function, neuropsychological deficits and structural and functional brain abnormalities. However, few functional brain imaging studies have been conducted using tasks of clinically relevant functions such as impulse control and reinforcement processing. Here we report on a study investigating the neural basis of behavioural inhibition and reward sensitivity in ASPD using functional magnetic resonance imaging (fMRI).
17 medication-free male individuals with DSM IV ASPD and 14 healthy controls were included. All subjects were screened for Axis I pathology and substance misuse. Scanner tasks included two block design tasks: one Go/No-Go task and one reward task. Scanning was carried out on a 1.5T Phillips system. Whole brain coverage was achieved using 40 axial slices with 3.5mm spacing a TR of 5 seconds. Data were analysed using SPM5 using random effects models.
Results of the Go/No-Go task confirmed brain activation previously described in the processing of impulse inhibition, namely in the orbitofrontal and dorsolateral prefrontal cortex and the anterior cingulate, and these were enhanced in the PD group. The reward task was associated with BOLD response changes in the reward network in both groups. However, these BOLD responses were reduced in the ASPD group, particularly in prefrontal areas.
Our results further support the notion of prefrontal dysfunction in ASPD. However, contrary to previous studies suggesting “hypofrontality” in this disorder, we found task specific increased and decreased BOLD responses.
Individuals with social anxiety disorder do poorly in residential treatment programs for the treatment of drug dependence. This is not surprising given the social nature of residential rehabilitation where group work and close social interactions are required.
Given the social nature of residential rehabilitation, we were interested in exploring whether we could address social anxiety symptoms prior to treatment entry and therefore enhance the likelihood that an individual would enter treatment and stay in treatment.
To conduct a randomised control trial to evaluate whether treatment of social anxiety symptoms prior to treatment entry improves treatment entry and retention.
Treatment seeking substance users (n = 105) completed intake assessment interviews for entry into a residential rehabilitation program. Assessment comprised the Mini International Neuropsychiatric interview (Mini), the alcohol, smoking and substance involvement screening test (ASSIST), the Liebowitz Social Anxiety Scale (LSAS). Participants were randomised to either a four-session social anxiety intervention or treatment as usual (which was to remain on the waiting list until treatment entry). A survival analysis was conducted to examine whether the intervention impacted on treatment retention.
The treatment did not significantly impact on treatment but the intervention group were significantly more likely to remain in treatment and this effect was only found in women.
For individuals with social anxiety disorder brief evidence based intervention focused on ameliorating social anxiety symptoms (e.g., cognitive behavioural treatment) may improve the retention in treatment. This effect appears to be gender specific.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
The available literature suggests that treatments and health services for psychosis are considered to be poorly organized and highly variable. Little is known, however, about how inpatient care is provided to individuals experiencing early psychosis. To facilitate quality improvement activities, we characterized the care this patient group receives in an inner city hospital.
We performed chart reviews of individuals admitted to psychiatric inpatient units at St. Paul's Hospital, Vancouver, British Columbia between 01/04/2014 and 31/03/2016. Those who were 17–25 years of age and hospitalized for psychotic symptoms at the time of admission were included. Demographic and health service use were summarized using descriptive characteristics.
We identified 73 inpatients (mean age = 22; males = 78%; Caucasian = 41%) that met study inclusion criteria, having a combined total of 102 care episodes and an average length of stay of 30.7 days (median = 18; min = 3; max = 268). Half of the care episodes were repeat admissions, with up to 30% of the patients readmitted within 28 days of discharge. Physical and mental status examinations (MSE) were performed in virtually all care episodes, although frequency is low (31.4% had daily physical examinations and 18.6% had MSE every nursing shift). In 49% and 50% of care episodes, patients were given oral antipsychotics and discharged on depot medications. Even when indicated, not all care episodes had follow-up appointments (60%) or referrals to income assistance (35%), community mental health teams (61%), and housing support (38%).
Specific programs are needed to address current gaps in inpatient care for patients with early psychosis.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
Key lifestyle-environ risk factors are operative for depression, but it is unclear how risk factors cluster. Machine-learning (ML) algorithms exist that learn, extract, identify and map underlying patterns to identify groupings of depressed individuals without constraints. The aim of this research was to use a large epidemiological study to identify and characterise depression clusters through “Graphing lifestyle-environs using machine-learning methods” (GLUMM).
Two ML algorithms were implemented: unsupervised Self-organised mapping (SOM) to create GLUMM clusters and a supervised boosted regression algorithm to describe clusters. Ninety-six “lifestyle-environ” variables were used from the National health and nutrition examination study (2009–2010). Multivariate logistic regression validated clusters and controlled for possible sociodemographic confounders.
The SOM identified two GLUMM cluster solutions. These solutions contained one dominant depressed cluster (GLUMM5-1, GLUMM7-1). Equal proportions of members in each cluster rated as highly depressed (17%). Alcohol consumption and demographics validated clusters. Boosted regression identified GLUMM5-1 as more informative than GLUMM7-1. Members were more likely to: have problems sleeping; unhealthy eating; ≤ 2 years in their home; an old home; perceive themselves underweight; exposed to work fumes; experienced sex at ≤ 14 years; not perform moderate recreational activities. A positive relationship between GLUMM5-1 (OR: 7.50, P < 0.001) and GLUMM7-1 (OR: 7.88, P < 0.001) with depression was found, with significant interactions with those married/living with partner (P = 0.001).
Using ML based GLUMM to form ordered depressive clusters from multitudinous lifestyle-environ variables enabled a deeper exploration of the heterogeneous data to uncover better understandings into relationships between the complex mental health factors.