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Compound-specific radiocarbon (14C) dating often requires working with small samples of < 100 µg carbon (µgC). This makes the radiocarbon dates of biomarker compounds very sensitive to biases caused by extraneous carbon of unknown composition, a procedural blank, which is introduced to the samples during the steps necessary to prepare a sample for radiocarbon analysis by accelerator mass spectrometry (i.e., isolating single compounds from a heterogeneous mixture, combustion, gas purification and graphitization). Reporting accurate radiocarbon dates thus requires a correction for the procedural blank. We present our approach to assess the fraction modern carbon (F14C) and the mass of the procedural blanks introduced during the preparation procedures of lipid biomarkers (i.e. n-alkanoic acids) and lignin phenols. We isolated differently sized aliquots (6–151 µgC) of n-alkanoic acids and lignin phenols obtained from standard materials with known F14C values. Each compound class was extracted from two standard materials (one fossil, one modern) and purified using the same procedures as for natural samples of unknown F14C. There is an inverse linear relationship between the measured F14C values of the processed aliquots and their mass, which suggests constant contamination during processing of individual samples. We use Bayesian methods to fit linear regression lines between F14C and 1/mass for the fossil and modern standards. The intersection points of these lines are used to infer F14Cblank and mblank and their associated uncertainties. We estimate 4.88 ± 0.69 μgC of procedural blank with F14C of 0.714 ± 0.077 for n-alkanoic acids, and 0.90 ± 0.23 μgC of procedural blank with F14C of 0.813 ± 0.155 for lignin phenols. These F14Cblank and mblank can be used to correct AMS results of lipid and lignin samples by isotopic mass balance. This method may serve as a standardized procedure for blank assessment in small-scale radiocarbon analysis.
Objectives: This study aimed to evaluate the influence of lower limb loss (LL) on mental workload by assessing neurocognitive measures in individuals with unilateral transtibial (TT) versus those with transfemoral (TF) LL while dual-task walking under varying cognitive demand. Methods: Electroencephalography (EEG) was recorded as participants performed a task of varying cognitive demand while being seated or walking (i.e., varying physical demand). Results: The findings revealed both groups of participants (TT LL vs. TF LL) exhibited a similar EEG theta synchrony response as either the cognitive or the physical demand increased. Also, while individuals with TT LL maintained similar performance on the cognitive task during seated and walking conditions, those with TF LL exhibited performance decrements (slower response times) on the cognitive task during the walking in comparison to the seated conditions. Furthermore, those with TF LL neither exhibited regional differences in EEG low-alpha power while walking, nor EEG high-alpha desynchrony as a function of cognitive task difficulty while walking. This lack of alpha modulation coincided with no elevation of theta/alpha ratio power as a function of cognitive task difficulty in the TF LL group. Conclusions: This work suggests that both groups share some common but also different neurocognitive features during dual-task walking. Although all participants were able to recruit neural mechanisms critical for the maintenance of cognitive-motor performance under elevated cognitive or physical demands, the observed differences indicate that walking with a prosthesis, while concurrently performing a cognitive task, imposes additional cognitive demand in individuals with more proximal levels of amputation.
To explore the use of fluorescence lifetime imaging microscopy in thyroid tissues, and to investigate how different thyroid lesions affect fluorescence lifetime.
Fluorescence lifetime measurements were taken of fresh frozen thyroid surgical specimens stained with fluorescein isothiocyanate tagged anti-thyroglobulin monoclonal antibodies.
The mean fluorescence lifetime measurements in 12 patients – 3 with multinodular goitre, 4 with follicular adenoma, 4 with papillary thyroid carcinoma and 1 with follicular carcinoma – were 3.16 ns (range, 2.66–3.52 ns), 3.75 ns (range, 2.99–4.57 ns), 2.97 ns (range, 2.57–3.21 ns) and 3.61 ns, respectively. The fluorescence lifetime of follicular adenoma patients was higher than that of papillary thyroid carcinoma patients by 26 per cent (p = 0.058). The fluorescence lifetime in the follicular carcinoma patient was similar to the follicular adenoma group, but higher than in the papillary thyroid carcinoma group by 22 per cent (p = 0.01).
Fluorescence lifetime measurements varied in different thyroid pathologies, possibly because of tissue-scale structural influences.
Background: Biallelic variants in POLR1C are associated with POLR3-related leukodystrophy (POLR3-HLD), or 4H leukodystrophy (Hypomyelination, Hypodontia, Hypogonadotropic Hypogonadism), and Treacher Collins syndrome (TCS). The clinical spectrum of POLR3-HLD caused by variants in this gene has not been described. Methods: A cross-sectional observational study involving 25 centers worldwide was conducted between 2016 and 2018. The clinical, radiologic and molecular features of 23 unreported and previously reported cases of POLR3-HLD caused by POLR1C variants were reviewed. Results: Most participants presented between birth and age 6 years with motor difficulties. Neurological deterioration was seen during childhood, suggesting a more severe phenotype than previously described. The dental, ocular and endocrine features often seen in POLR3-HLD were not invariably present. Five patients (22%) had a combination of hypomyelinating leukodystrophy and abnormal craniofacial development, including one individual with clear TCS features. Several cases did not exhibit all the typical radiologic characteristics of POLR3-HLD. A total of 29 different pathogenic variants in POLR1C were identified, including 13 new disease-causing variants. Conclusions: Based on the largest cohort of patients to date, these results suggest novel characteristics of POLR1C-related disorder, with a spectrum of clinical involvement characterized by hypomyelinating leukodystrophy with or without abnormal craniofacial development reminiscent of TCS.
A procedure using tube excited energy dispersive x-ray fluorescence analysis with interelement corrections has been developed for multielement analysis of major and trace elements and ash content of coal, coke, and fly ash. The procedure uses pressed pellets and an exponential correction for interelement effects. The average deviations ranged from about 0.0003% for V at an average concentration of about .003% to 0.1% for S at an average concentration of 4%. About 25 elements were measured and 100 second minimum detectable concentrations ranged from about one part per million for elements near arsenic to about one tenth of one percent for sodium.
The creation of digital repositories of human skeletal remains offers bioarchaeologists a variety of potential means of aiding efforts related to curation and analysis. We present a discussion of how issues of preservation and access can affect research and argue that digital repositories not only maintain a record of objects but that the digital format allows researchers to expand their studies to include otherwise inaccessible collections. Digital models can be utilized by bioarchaeologists to collect and analyze a wide variety of quantitative and qualitative data. We review several digital capture methods employed by bioarchaeologists, including CT scanning, laser scanning, and photogrammetry. While photogrammetry is underutilized by bioarchaeologists, we point out its many advantages over other methods.
Objectives: To adequately monitor the course of cognitive functioning in persons with moderate to severe dementia, relevant cognitive tests for the advanced dementia stages are needed. We examined the ability of a test developed for the advanced dementia stages, the Severe Impairment Battery Short version (SIB-S), to measure cognitive change over time. Second, we examined type of memory impairment measured with the SIB-S in different dementia stages. Methods: Participants were institutionalized persons with moderate to severe dementia (N = 217). The SIB-S was administered at 6-month intervals during a 2-year period. Dementia severity at baseline was classified according to Global Deterioration Scale criteria. We used mixed models to evaluate the course of SIB-S total and domain scores, and whether dementia stage at baseline affected these courses. Results: SIB-S total scores declined significantly over time, and the course of decline differed significantly between dementia stages at baseline. Persons with moderately severe dementia declined faster in mean SIB-S total scores than persons with moderate or severe dementia. Between persons with moderate and moderately severe dementia, there was only a difference in the rate of decline of semantic items, but not episodic and non-semantic items. Conclusions: Although modest floor and slight ceiling effects were noted in severe and milder cases, respectively, the SIB-S proved to be one of few available adequate measures of cognitive change in institutionalized persons with moderate to severe dementia. (JINS, 2019, 25, 204–214)
AFM-based nanoelectrical modes have numerous
applications in fields ranging from semiconductors
to biology. The data produced have traditionally
been in the form of a 2D map, generated in contact
mode, with a single electrical data point per
XY location. Electrical ramps
or spectra would be generated at a few, carefully
selected locations. This article discusses a new
approach to nanoelectrical imaging that creates an
electrical data cube and a correlated nanomechanical
data cube while operating at normal imaging speeds.
This approach avoids contact mode imaging, thus
extending electrical measurements to soft and
fragile samples and improving measurement
consistency. Moreover, this is a general approach
that is applicable to most nanoelectrical modes and
High-residue cover crops can facilitate organic no-till vegetable production when cover crop biomass production is sufficient to suppress weeds (>8000 kg ha−1), and cash crop growth is not limited by soil temperature, nutrient availability, or cover crop regrowth. In cool climates, however, both cover crop biomass production and soil temperature can be limiting for organic no-till. In addition, successful termination of cover crops can be a challenge, particularly when cover crops are grown as mixtures. We tested whether reusable plastic tarps, an increasingly popular tool for small-scale vegetable farmers, could be used to augment organic no-till cover crop termination and weed suppression. We no-till transplanted cabbage into a winter rye (Secale cereale L.)-hairy vetch (Vicia villosa Roth) cover crop mulch that was terminated with either a roller-crimper alone or a roller-crimper plus black or clear tarps. Tarps were applied for durations of 2, 4 and 5 weeks. Across tarp durations, black tarps increased the mean cabbage head weight by 58% compared with the no tarp treatment. This was likely due to a combination of improved weed suppression and nutrient availability. Although soil nutrients and biological activity were not directly measured, remaining cover crop mulch in the black tarp treatments was reduced by more than 1100 kg ha−1 when tarps were removed compared with clear and no tarp treatments. We interpret this as an indirect measurement of biological activity perhaps accelerated by lower daily soil temperature fluctuations and more constant volumetric water content under black tarps. The edges of both tarp types were held down, rather than buried, but moisture losses from the clear tarps were greater and this may have affected the efficacy of clear tarps. Plastic tarps effectively killed the vetch cover crop, whereas it readily regrew in the crimped but uncovered plots. However, emergence of large and smooth crabgrass (Digitaria spp.) appeared to be enhanced in the clear tarp treatment. Although this experiment was limited to a single site-year in New Hampshire, it shows that use of black tarps can overcome some of the obstacles to implementing cover crop-based no-till vegetable productions in northern climates.
Frequency-dependence and magnitude of second harmonic generation (SHG) from ~4 × 105 nm2 molybdenum disulfide (MoS2) monolayers was examined in presence of single 150 nm plasmonic gold@silica shell@core nanoantenna monomer and dimers. Quantitative agreement between discrete dipole approximation-calculated fields and measured SHG enhancements was found. SHG from MoS2 was enhanced up to 1.88 × upon deposition of a plasmonic nanoantenna-dimer with 170 nm gap, reaching maximal normalized SHG conversion efficiency of 0.0250%/W. Pump losses attributable to plasmonic damping, e.g., scattering and/or hot-electron injection into MoS2, were apparent. Linear and nonlinear optical activity of MoS2 and nanoantenna controls were compared with literature values.
Background: A major concern of patients undergoing Gamma Knife radiosurgery (GKS) for benign tumors and other conditions is the risk of a separate secondary malignancy or malignant -transformation. The incidence of radiosurgery-associated malignancy based on long-term follow-up remains unknown. Methods: We conducted a population-based cohort study to estimate the incidence rate of both malignant transformation and a separate radiation-associated malignancy in patients undergoing GKS from 1987 to 2016 at 5 centers. Results: 11 527 patients underwent radiosurgery for meningioma (n=3261), arteriovenous malformation (n=2868), trigeminal neuralgia (n=1982), vestibular schwannoma (n=1957), pituitary adenoma (n=1193), other (n=266). The follow-up time ranged from 0.3 to 23.8 years. Four cases of malignant transformation and 3 new malignant brain tumors were reported, two of which were not within the irradiated field. The incidence of malignant transformation was 6.6 per 100 000 patient-years and of new malignancy, either locally or distant, was 5 in 100 000 patient-years. These risks are not higher than the Central Brain Tumor Registry of the United States derived annual incidence rate of all primary malignant CNS tumors of 7.15 per 100 000. Conclusions: Physicians can safely counsel patients that the risk of malignancy after stereotactic radiosurgery remains extremely low, even at long-term follow-up of greater than 10 years.
Selecting bulls for reproductive soundness requires that the bull be structurally sound, free of abnormalities that impair his ability to produce adequate numbers of motile, morphologically normal spermatozoa, and be able to successfully complete coitus. This review discusses the diagnosis and etiology of abnormalities of the penis, prepuce as well as common musculoskeletal conditions that prevent normal pasture breeding soundness. A review of testicular and thermoregulation addresses the potential impact of musculoskeletal disorders on normal sperm production.
Traumatic stressors during childhood and adolescence are associated with psychopathology, mostly studied in the context of post-traumatic stress disorder (PTSD) and depression. We investigated broader associations of traumatic stress exposure with psychopathology and cognition in a youth community sample.
The Philadelphia Neurodevelopmental Cohort (N = 9498) is an investigation of clinical and neurobehavioral phenotypes in a diverse (56% Caucasian, 33% African American, 11% other) US youth community population (aged 8–21). Participants were ascertained through children's hospital pediatric (not psychiatric) healthcare network in 2009–2011. Structured psychiatric evaluation included screening for lifetime exposure to traumatic stressors, and a neurocognitive battery was administered.
Exposure rate to traumatic stressful events was high (none, N = 5204; one, N = 2182; two, N = 1092; three or more, N = 830). Higher stress load was associated with increased psychopathology across all clinical domains evaluated: mood/anxiety (standardized β = .378); psychosis spectrum (β = .360); externalizing behaviors (β = .311); and fear (β = .256) (controlling for covariates, all p < 0.001). Associations remained significant controlling for lifetime PTSD and depression. Exposure to high-stress load was robustly associated with suicidal ideation and cannabis use (odds ratio compared with non-exposed 5.3 and 3.2, respectively, both p < 0.001). Among youths who experienced traumatic stress (N = 4104), history of assaultive trauma was associated with greater psychopathology and, in males, vulnerability to psychosis and externalizing symptoms. Stress load was negatively associated with performance on executive functioning, complex reasoning, and social cognition.
Traumatic stress exposure in community non-psychiatric help-seeking youth is substantial, and is associated with more severe psychopathology and neurocognitive deficits across domains, beyond PTSD and depression.
From a 45ks Chandra observation of V42G Oph we have obtained high-resolution X-ray spectra at moderate signal-to-noise, and a, good quality, uninterrupted lightcurve. The spectra are reasonably fit with a cooling flow model, similar to EX Hya and U Gem. Our analysis of the Chandra and additional X-ray/optical lightcurves reveals a persistent modulation at 4.2 hr from 1988 to 2003, likely the white dwarf spin period indicating an intermediate polar nature for V426 Oph.
The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.
Recent studies found that mobile phone users had a significantly greater risk of having elevated thresholds in speech frequencies. This study investigated the correlation between the laterality of sudden sensorineural hearing loss, handedness and the preferred ear for mobile phone use.
The study included all patients who presented with sudden sensorineural hearing loss to the Department of Otolaryngology – Head and Neck Surgery in our tertiary referral medical centre between 2014 and 2016. Patients were asked to indicate their dominant hand and preferred ear for mobile phone use.
The study comprised 160 patients. No correlation was found between the dominant hand or preferred ear for mobile phone use and the side of sudden sensorineural hearing loss. There was no correlation between the side of the sudden sensorineural hearing loss (preferable or non-preferable for mobile phone use) and audiometric characteristics.
No correlation was found between the laterality of ears used for mobile phone and sudden sensorineural hearing loss.
Carcass conformation has been found to be associated with fatness among carcasses of similar weight and subjectively assessed fat cover (Kempster et al., 1981), leading these authors to suggest that assessments of conformation in live animals were even more likely to be confounded with fatness. Consequently, selection for improved shape would likely be opposed to the overall objective of reduced fatness in lamb carcasses. However, conformation remains a highly valued trait among lamb producers and breeders. In principle, shape can also be related to variation in lean: bone ratio and muscularity, defined as the depth of muscle relative to the skeletal dimension. The objectives of this work were to compare a live animal assessment of the conformation of the hind leg and ultrasonic measures of muscle and fat depths as predictors of carcass composition and muscularity.