Investigating the existence of an osmotic barrier between xylem fibres and vessels in sugar maple (Acer saccharum) using microCT.

Sugar maples (Acer saccharum Marshall) develop elevated stem pressures in springtime through the compression and expansion of gas bubbles present within xylem fibres. The stability of this gas within the fibres is hypothesised to be due to the elevated sugar concentration of maple sap and the presence of an osmotic barrier between fibres and vessels. Without this osmotic barrier gas bubbles are predicted to dissolve rapidly. In this work we investigated the existence of this osmotic barrier. We quantified the fraction of the xylem occupied by gas-filled fibres using synchrotron based microCT. After imaging fresh stem segments we perfused them with either a 2% sucrose solution or water, imaging again following perfusion. In this way we directly observed how total gas present in the fibres changed when an osmotic pressure difference should be present, with the 2% sucrose solution, and when it is absent, with the water. Following a first round of perfusion we perfused stem segments with the other perfusate, repeating this multiple times to observe how switching perfusates affected gas-filled fibres. We found that perfusing stem segments with water resulted in a significant reduction in the xylem fibre gas, but perfusing stem segments with a sucrose solution did not significantly reduce the gas in the fibres. These results support the hypothesis that an osmotic barrier exists between fibres and vessels.

Modeling the spatiotemporal patterns and drivers of Dungeness crab fishing effort to inform whale entanglement risk mitigation on the U.S. West Coast.

Understanding and characterizing the spatiotemporal dynamics of fishing fleets is crucial for ecosystem-based fisheries management (EBFM). EBFM must not only account for the sustainability of target species catches, but also for the collateral impacts of fishing operations on habitats and non-target species. Increased rates of large whale entanglements in commercial Dungeness crab fishing gear have made reducing whale-fishery interactions a current and pressing challenge on the U.S. West Coast. While several habitat models exist for different large whale species along the West Coast, less is known about the crab fishery and the degree to which different factors influence the intensity and distribution of aggregate fishing effort. Here, we modeled the spatiotemporal patterns of Dungeness crab fishing effort in Oregon and Washington as a function of environmental, economic, temporal, social, and management related predictor variables using generalized linear mixed effects models. We then assessed the predictive performance of such models and discussed their usefulness in informing fishery management. Our models revealed low between-year variability and consistent spatial and temporal patterns in commercial Dungeness crab fishing effort. However, fishing effort was also responsive to multiple environmental, economic and management cues, which influenced the baseline effort distribution pattern. The best predictive model, chosen through out-of-sample cross-validation, showed moderate predictive performance and relied upon environmental, economic, and social covariates. Our results help fill the current knowledge gap around Dungeness crab fleet dynamics, and support growing calls to integrate fisheries behavioral data into fisheries management and marine spatial planning.

Counselors' Perceptions of Their Preparedness for Telemental Health Services: A Phenomenological Examination.

Background: To examine counselors' perceptions of their formal preparation for engaging in telemental health (TMH) counseling with the intent of gaining an understanding of their lived experiences. Materials and Methods: Semistructured interviews were conducted with seven seasoned counselors who regularly engage in technology-mediated distance counseling. Results: The results highlighted themes within two emerging categories: the counselor and training/education. Themes related to motivation and specific counselor attributes emerged from the first category and themes of availability, inadequacy, and modality emerged from the second category. Discussion: The implications from this study suggest a lack of availability and standardization of effective training on TMH delivery. Conclusion: This study identifies areas of potential future research related to counselors' preparation experiences as well specific areas of need for TMH training in counseling graduate programs and other natural opportunities.

Quantitative examination of the anatomy of the juvenile sugar maple xylem.

New methodologies have enabled viable sap yields from juvenile sugar maple trees. To further improve yields, a better understanding of sap exudation is required. To achieve this, the anatomy of the xylem must first be fully characterised. We examine juvenile maple saplings using light optical microscopy (LOM) and scanning electron microscopy (SEM), looking at sections cut along differing orientations as well as macerations. From this we measure various cell parameters. We find diameter and length of vessel elements to be 28 ± 8 µm and 200 ± 50 µm, for fibre cells 8 ± 3 µm and 400 ± 100 µm, and for ray parenchyma cells 8 ± 2 µm and 50 ± 20 µm. We also examine pitting present on different cell types. On vessel elements we observe elliptical bordered pits connecting to other vessel elements (with major axis of 2.1 ± 0.7 µm and minor 1.3 ± 0.3 µm) and pits connecting to ray parenchyma (with major axis of 4 ± 2 µm and minor 2.0 ± 0.7 µm). We observe two distinct pit sizes on fibres with circular pits 0.7 ± 0.2 µm in diameter and ellipsoidal pits 1.6 ± 0.4 µm by 1.0 ± 0.3 µm. We do not observe distinct pitting patterns on different fibre types. The various cell and pit measurements obtained generally agree with the limited data available for mature trees, with the exception of vessel element and fibre length, both of which were significantly smaller than reported values.

Cycles of satellite and transposon evolution in Arabidopsis centromeres.

Centromeres are critical for cell division, loading CENH3 or CENPA histone variant nucleosomes, directing kinetochore formation and allowing chromosome segregation1,2. Despite their conserved function, centromere size and structure are diverse across species. To understand this centromere paradox3,4, it is necessary to know how centromeric diversity is generated and whether it reflects ancient trans-species variation or, instead, rapid post-speciation divergence. To address these questions, we assembled 346 centromeres from 66 Arabidopsis thaliana and 2 Arabidopsis lyrata accessions, which exhibited a remarkable degree of intra- and inter-species diversity. A. thaliana centromere repeat arrays are embedded in linkage blocks, despite ongoing internal satellite turnover, consistent with roles for unidirectional gene conversion or unequal crossover between sister chromatids in sequence diversification. Additionally, centrophilic ATHILA transposons have recently invaded the satellite arrays. To counter ATHILA invasion, chromosome-specific bursts of satellite homogenization generate higher-order repeats and purge transposons, in line with cycles of repeat evolution. Centromeric sequence changes are even more extreme in comparison between A. thaliana and A. lyrata. Together, our findings identify rapid cycles of transposon invasion and purging through satellite homogenization, which drive centromere evolution and ultimately contribute to speciation.

Performance of various 3D-printed monolith geometries as an alternative to expanded bed adsorption for protein purification.

Here, we compare the performance of various three-dimensional-printed Monolith Adsorption (PMA) columns designed from a triply periodic minimal surface geometry, the Schoen gyroid. The structures examined had designed hydraulic diameters between 203 and 458 µm and voidages of 40%-60%. We compare column efficiency, porosity, static binding capacity and dynamic binding capacity for various load volumes and flow rates. The results show that all structures allowed efficient passage of yeast cells (>97%) over a wide range of interstitial velocities (191 to 1911 cm/h) while maintaining a low pressure drop (<0.1 MPa). The structure with a voidage of 40% and a hydraulic diameter of 203 µm showed the best performance in all aspects evaluated. Bovine serum albumin (BSA) recoveries for all structures (27%-91% when the loaded volume was 180 mL) were significantly affected by hydraulic diameter, mean channel wall thickness, velocity and voidage. Moreover, biomass addition resulted in a decrease in BSA recovery, which became more obvious at high velocities. However, this did not lead to a dramatic reduction in saturated binding capacity, significant changes in axial dispersion, or blockage of channels and could be compensated for by recirculation of the feed, even at high velocity. PMA thus potentially provides an appealing alternative to Expanded Bed Adsorption, retaining the latter's advantages, while eliminating fluidization issues and minimizing both processing time and buffer consumption.

Examination of embolisms in maple and birch saplings utilising microCT.

We demonstrate the application of synchrotron x-ray microtomography (microCT) to non-invasively examine the internal structure of a maple and birch sapling. We show that, through the use of standard image analysis techniques, embolised vessels can be extracted from reconstructed slices of the stem. By combining these thresholded images with connectivity analysis, we map out the embolisms within the sapling in three dimensions and evaluate the size distribution, showing that large embolisms over 0.005 mm3 in volume compose the majority of the saplings' total embolised volume. Finally we evaluate the radial distribution of embolisms, showing that in maple fewer embolisms are present towards the cambium, while birch has a more uniform distribution.

Detection of honey adulteration using benchtop 1H NMR spectroscopy.

High magnetic field NMR spectroscopy featuring the use of superconducting magnets is a powerful analytical technique for the detection of honey adulteration. Such high field NMR systems are, however, typically housed in specialised laboratories, require cryogenic coolants, and necessitate specialist training to operate. Benchtop NMR spectrometers featuring permanent magnets are, by comparison, significantly cheaper, more mobile and can be operated with minimal expertise. The lower magnetic fields used in such systems, however, result in limited spectral resolution, which diminishes their ability to perform quantitative composition analysis. These limitations may be overcome by implementing a recently developed field-invariant model-based fitting method which is defined by the underlying quantum mechanical properties of the nuclear spin system; this method is applied here to quantify the sugar composition of honey using benchtop 1H NMR (43 MHz) spectroscopy. The detection of adulteration of 26 honey samples with brown rice syrup is quantitatively demonstrated to a minimum adulterant concentration of 5 wt%. Honey adulteration with corn syrup, glucose syrup and wheat syrup was also quantitatively detected using this approach. Our NMR detection of adulteration was shown to be invariant with time over 60 days of storage.

A numerical investigation of the hydrodynamic dispersion in triply periodic chromatographic stationary phases.

3D printed custom chromatographic stationary phases have recently been demonstrated. Using the Lattice Boltzmann Method, we compared the model-predicted chromatographic performance of random packing of monodisperse spheres, open tubular columns (OTC) and stationary phases based on three triply periodic minimal surfaces (TPMS): Schwarz Diamond (SD), Schoen Gyroid (SG) and Schwarz Primitive (SP). Three performance metrics were employed in this comparison: i) reduced plate height, ii) Darcy number, iii) kinetic performance factor. Each simulated geometry was unconfined with an impermeable stationary phase to remove wall effects and pore diffusion. The performance was studied for macro-porosities in the range 0.2 to 0.8, depending on the geometry. OTCs were found to have superior permeability to both random sphere packing and TPMS structures across the entire porosity range. At porosity greater than 0.366, the Schwarz Diamond medium achieved the lowest levels of band broadening and greatest kinetic performance. The reduced plate height of all stationary phase geometries was shown to increase with bed porosity. The kinetic performance was found to increase with porosity for TPMS structures, decrease with porosity for random packing and be independent of porosity for OTCs. This work illustrates that chromatographic stationary phase geometries based on TPMS structures are theoretically competitive with random packing and open tubular columns and their feasibility for practical chromatography should continue to be explored.

Accurate measurements of self-diffusion coefficients with benchtop NMR using a QM model-based approach.

The measurement of self-diffusion coefficients using pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy is a well-established method. Recently, benchtop NMR spectrometers with gradient coils have also been used, which greatly simplify these measurements. However, a disadvantage of benchtop NMR spectrometers is the lower resolution of the acquired NMR signals compared to high-field NMR spectrometers, which requires sophisticated analysis methods. In this work, we use a recently developed quantum mechanical (QM) model-based approach for the estimation of self-diffusion coefficients from complex benchtop NMR data. With the knowledge of the species present in the mixture, signatures for each species are created and adjusted to the measured NMR signal. With this model-based approach, the self-diffusion coefficients of all species in the mixtures were estimated with a discrepancy of less than 2 % compared to self-diffusion coefficients estimated from high-field NMR data sets of the same mixtures. These results suggest benchtop NMR is a reliable tool for quantitative analysis of self-diffusion coefficients, even in complex mixtures.

Sleep Disturbance and Its Association With Sluggish Cognitive Tempo and Attention in Pediatric Brain Tumor Survivors.

Background: Pediatric brain tumor (PBT) survivors are at risk for developing sleep disturbances. While in other pediatric populations sleep disturbance has been associated with worse cognitive functioning, it is unclear to what extent this relationship generalizes to PBT survivors. The aim of the current study was to assess the relationship between sleep disturbance and aspects of cognition, including sluggish cognitive tempo (SCT) as well as attention and working memory. Materials and Methods: Eighty-three PBT survivors 6-18 years of age who were at least 3 months post-treatment were included in the present cross-sectional study. Level of sleep disturbance was measured as a composite score reflecting various sleep problems as rated by caregivers. Cognitive measures included caregiver-ratings of sluggish cognitive tempo and attention problems, as well as performance-based cognitive measures assessing attention and executive functioning. Hierarchical regression analysis was used to assess associations between sleep and cognition. Results: Of all caregivers, 32.5% reported one or more sleep disturbances as "very/often true" and over 68% of caregivers rated at least one sleep-related item as "somewhat true." Of all cognitive variables, scores were most frequently impaired for SCT (30%). A higher level of sleep disturbance was associated with worse SCT and parent-rated attention problems. Associations between sleep and performance-based cognitive measures assessing attention and working memory were not statistically significant. Conclusion: Findings of the current study highlight the importance of further investigation into the relationship between sleep and cognition in PBT survivors, which may assist efforts to maximize cognitive outcome and health-related quality of life in PBT survivors. The current study additionally suggests further investigation of SCT in this population is warranted, as it may be more sensitive to detecting possible associations with sleep disturbance relative to discrete measures that assess cognitive performance under ideal circumstances.

Coexpression of MEIOTIC-TOPOISOMERASE VIB-dCas9 with guide RNAs specific to a recombination hotspot is insufficient to increase crossover frequency in Arabidopsis.

During meiosis, homologous chromosomes pair and recombine, which can result in reciprocal crossovers that increase genetic diversity. Crossovers are unevenly distributed along eukaryote chromosomes and show repression in heterochromatin and the centromeres. Within the chromosome arms, crossovers are often concentrated in hotspots, which are typically in the kilobase range. The uneven distribution of crossovers along chromosomes, together with their low number per meiosis, creates a limitation during crop breeding, where recombination can be beneficial. Therefore, targeting crossovers to specific genome locations has the potential to accelerate crop improvement. In plants, meiotic crossovers are initiated by DNA double-strand breaks that are catalyzed by SPO11 complexes, which consist of 2 catalytic (SPO11-1 and SPO11-2) and 2 noncatalytic subunits (MTOPVIB). We used the model plant Arabidopsis thaliana to coexpress an MTOPVIB-dCas9 fusion protein with guide RNAs specific to the 3a crossover hotspot. We observed that this was insufficient to significantly change meiotic crossover frequency or pattern within 3a. We discuss the implications of our findings for targeting meiotic recombination within plant genomes.

Well-Being and Help-Seeking Among Assemblies of God Ministers in the USA.

This study examined Assemblies of God pastors in the USA (n = 874) on role identity, well-being, religious coping, and attitudes toward seeking professional counseling. Overall, 14.1% had depression at moderate or higher severity based on the PHQ-9 scale (score of 10 or above), with an additional 25.7% in the mild category (score of 5-9). On the Clergy Spiritual Well-Being scale, 9.2% had poor spiritual well-being in everyday life, while 18.1% showed poor spiritual well-being in ministry (score below 15 on each respective subscale). About 20% of the sample scored in the high range (above 10) on the Clergy Occupational Distress Index. Male role norms, occupational distress, and positive religious coping were predictive of help-seeking attitudes. Those who were married, younger, more highly educated, female, or had more close friends had more positive attitudes toward seeking counseling.

Quantification of mixtures of analogues of illicit substances by benchtop NMR spectroscopy.

This paper investigates the possibility of using benchtop NMR spectroscopy for quantification of illicit drugs (methamphetamine) in binary and ternary mixtures with impurities and cutting agents (N-isopropylbenzylamine, phenethylamine and dimethylsulfone). To avoid handling regulated substances, methamphetamine in our experiments is substituted with amino-2-propanol, which has similar functional groups and chemical structure to methamphetamine and hence a related NMR spectrum. Binary and ternary mixtures at concentrations from 30 mmol/L up to 500 mmol/L for each of these species were measured using a 60 MHz benchtop spectrometer. The spectra were analysed using both integration and a model-based algorithm that relies on a full quantum mechanical description of the studied spin systems. Both techniques were able to quantify the composition of the mixtures. The root mean squared error in the measured concentration using the model-based algorithm was < 10 mmol/L, whereas the error using integration was typically > 20 mmol/L. Thus, we conclude benchtop NMR is viable for quantitative measurements of mixtures of illicit substances, particularly when coupled with a quantum mechanical model for the analysis.

Quantitative analysis of wine and other fermented beverages with benchtop NMR.

We present a fully automated approach for quantitative compositional analysis of fermented beverages using benchtop nuclear magnetic resonance (NMR) spectroscopy. NMR spectroscopy, renowned for its applications in chemical structure elucidation, is gaining attention as a quantitative analytical technique due to its inherent linearity and the ability to obtain comprehensive quantitative information with a single simple experiment. Recently developed benchtop NMR spectrometers offer the quantitative capabilities of NMR to a wide range of potential users in industry, but their applicability has been limited by the reduced effective spectral resolution and the need for more advanced data processing. We address this problem with a model-based algorithm that hinges on the well-understood description of quantum mechanical phenomena in NMR spectroscopy. We demonstrate the effectiveness of our approach on a challenging problem of analysing the composition of wine and related fermented beverages - an important potential niche application of quantitative NMR. We successfully quantify more than 15 major components in the wine matrix and enable the quantification of species whose analysis is generally not possible with established methods. The average discrepancy of the obtained concentrations, when compared to the traditional methods of analysis, usually does not exceed 10% and is lower for the most abundant species (e.g. below 5% for ethanol).

Quantitative frother analysis on coal mine process water with a benchtop NMR spectrometer.

This paper investigates the use of a benchtop NMR for quantification of a commonly used frothing agent, methyl isobutyl carbinol (MIBC) in the process water of a coal preparation facility. Solid phase extraction is used to increase the concentration of MIBC in the sample so that it is quantifiable by a benchtop NMR. A polymeric, reversed phase column with methanol as solvent gives a MIBC recovery rate of 67 ± 4% as determined using 400 MHz high-field NMR. The recovery rate consistently falls in the above narrow range even in the presence of diesel and inorganic electrolytes which are likely present as background chemicals in the process water. Using the average MIBC recovery rate, we use a quantum mechanical model to analyse the intensity of MIBC in the benchtop spectra. The quantum mechanical modelling algorithm effectively excludes the effect of the diesel on the measured NMR signal. The quantification error when the inlet concentration of MIBC is between 1 and 12 mg/L (1.2-15 ppm v/v), is within 0.5 mg/L (0.6 ppm v/v).

Crossover-active regions of the wheat genome are distinguished by DMC1, the chromosome axis, H3K27me3, and signatures of adaptation.

The hexaploid bread wheat genome comprises over 16 gigabases of sequence across 21 chromosomes. Meiotic crossovers are highly polarized along the chromosomes, with elevation in the gene-dense distal regions and suppression in the Gypsy retrotransposon-dense centromere-proximal regions. We profiled the genomic landscapes of the meiotic recombinase DMC1 and the chromosome axis protein ASY1 in wheat and investigated their relationships with crossovers, chromatin state, and genetic diversity. DMC1 and ASY1 chromatin immunoprecipitation followed by sequencing (ChIP-seq) revealed strong co-enrichment in the distal, crossover-active regions of the wheat chromosomes. Distal ChIP-seq enrichment is consistent with spatiotemporally biased cytological immunolocalization of DMC1 and ASY1 close to the telomeres during meiotic prophase I. DMC1 and ASY1 ChIP-seq peaks show significant overlap with genes and transposable elements in the Mariner and Mutator superfamilies. However, DMC1 and ASY1 ChIP-seq peaks were detected along the length of each chromosome, including in low-crossover regions. At the fine scale, crossover elevation at DMC1 and ASY1 peaks and genes correlates with enrichment of the Polycomb histone modification H3K27me3. This indicates a role for facultative heterochromatin, coincident with high DMC1 and ASY1, in promoting crossovers in wheat and is reflected in distalized H3K27me3 enrichment observed via ChIP-seq and immunocytology. Genes with elevated crossover rates and high DMC1 and ASY1 ChIP-seq signals are overrepresented for defense-response and immunity annotations, have higher sequence polymorphism, and exhibit signatures of selection. Our findings are consistent with meiotic recombination promoting genetic diversity, shaping host-pathogen co-evolution, and accelerating adaptation by increasing the efficiency of selection.

Quantitative measurement of solid fraction in a silo using SPRITE.

The purpose of this study is to develop MRI methods to measure the solid fraction in granular flows quantitatively. It is increasingly recognised that solid fraction plays a key role in granular rheology, but experimental characterisation of it during flow is challenging. Here centric sectoral-SPRITE imaging is applied to image mustard seeds discharging from a 3D-printed hopper. Quantitative images are obtained after considering and correcting artefacts that may arise from flow and relaxation. The image intensity is then further corrected for spatial variations in the B1 field. Various maps of nominally homogeneous samples were tested to correct for variations in the B1 field. The B1 field was found to be sensitive to the geometry of the sample and the material in the sample. Hence, here static images of the seeds in the hopper were used to correct for B1 field variations. Moreover, small signal variations were observed from measurements performed on different days owing to subtle differences in the spectrometer operation. Here an internal standard was used to scale the signal intensity and correct for these variations. Following these corrections, a linear correlation (R2 = 0.999) was observed between the scaled image intensities and the known solid fractions of packed samples with solid fractions between 0.55 and 0.64. This correlation was used as a calibration of the 3D image of the hopper to extract quantitative time-averaged spatial maps of solid fraction during steady flow. The measurements were confirmed to be quantitative by also measuring the velocity of the particles. Together these measurements were used to calculate a mass flow rate in the hopper, which was consistent with the mass flow measured gravimetrically.