Nematic liquid crystals lack positional order of their constituent molecules, which share an average orientational order only. Modulated nematic liquid crystal phases also lack positional order, but ...possess a periodic variation in this direction of average orientation. In the recently discovered splay nematic (N
S
) phase the average orientational order is augmented with a periodic splay deformation of orientation perpendicular to the director. In this communication we report the first example of a splay nematic phase which is chemically induced by mixing two materials, neither of which exhibit the N
S
phase. The splay-nematic phase is identified based on its optical textures, X-ray scattering patterns, and small enthalpy of the associated phase transition. We measure the splay periodicity optically, finding it to be ∼9 μm. This unexpected generation of the splay-nematic phase through binary mixtures offers a new route to materials which exhibit this phase which complements ongoing studies into structure-property relationships and could accelerate the development of technologies utilising this remarkable polar nematic variant.
We find that the splay nematic phase can be chemically induced in binary mixtures of two materials, neither of which exhibits the splay nematic phase in their neat state.
Recent observations of the solar wind have pointed out the existence of a cascade of magnetic energy from the scale of the proton Larmor radius ρ(p) down to the electron Larmor radius ρ(e) scale. In ...this Letter we study the spatial properties of magnetic field fluctuations in the solar wind and find that at small scales the magnetic field does not resemble a sea of homogeneous fluctuations, but rather a two-dimensional plane containing thin current sheets and discontinuities with spatial sizes ranging from l >/~ ρ(p) down to ρ(e) and below. These isolated structures may be manifestations of intermittency that localize sites of turbulent dissipation. Studying the relationship between turbulent dissipation, reconnection, and intermittency is crucial for understanding the dynamics of laboratory and astrophysical plasmas.
Turbulence is ubiquitous in the solar wind. Turbulence causes kinetic and magnetic energy to cascade to small scales where they are eventually dissipated, adding heat to the plasma. The details of ...how this occurs are not well understood. This article reviews the evidence for turbulent dissipation and examines various diagnostics for identifying solar wind regions where dissipation is occurring. We also discuss how future missions will further enhance our understanding of the importance of turbulence to solar wind dynamics.
It is generally accepted that physical activity reduces the risk of coronary events. This study focused on whether walking, an activity of only moderate intensity, protects against coronary events in ...postmenopausal women. Walking was associated with risk reductions similar to those associated with vigorous exercise. The findings applied equally to both white women and black women.
In postmenopausal women, brisk walking for at least 2.5 hours per week reduces the risk of coronary events.
Physical activity has been associated with a reduced risk of cardiovascular disease in epidemiologic studies,
1
,
2
but data for women and members of minority ethnic groups have been sparse. Moreover, the specific role of walking, the most common form of exercise among women,
3
has been addressed only minimally. Federal guidelines from the Centers for Disease Control and Prevention and the American College of Sports Medicine,
4
as well as the Surgeon General's Report on Physical Activity and Health,
3
endorse at least 30 minutes of moderate-intensity physical activity on most, and preferably all, days of the week, in contrast to earlier guidelines . . .
Low-density astrophysical plasmas may be described by magnetohydrodynamics at large scales, but require kinetic description at ion scales in order to include dissipative processes that terminate the ...cascade. Here kinetic plasma simulations and high-resolution spacecraft observations are compared to facilitate the interpretation of signatures of various dissipation mechanisms. Kurtosis of increments indicates that kinetic scale coherent structures are present, with some suggestion of incoherent activity near ion scales. Conditioned proton temperature distributions suggest heating associated with coherent structures. The results reinforce the association of intermittent turbulence, coherent structures, and plasma dissipation.
Blood brain barrier impairment occurs early in the course of infection by HIV and it may persist in a subset of patients despite effective antiretroviral treatment. We tested the hypothesis that ...HIV-positive patients with dysfunctional blood brain barrier may have altered biomarkers of neuronal damage. In adult HIV-positive highly active antiretroviral treatment (HAART)-treated patients (without central nervous system infections and undergoing lumbar punctures for clinical reasons) cerebrospinal fluid albumin to serum ratios (CSAR), total tau, phosphorylated tau, 1–42 beta amyloid, and neopterin were measured. In 101 adult patients, cerebrospinal fluid-to-serum albumin ratios were 4.8 (3.7–6.1) with 12 patients (11.9 %) presenting age-defined impaired blood brain barrier. A significant correlation was observed between CSAR and total tau (
p
= 0.005), phosphorylated tau (
p
= 0.008), and 1–42 beta amyloid (
p
= 0.040). Patients with impaired blood brain barrier showed significantly higher total tau (201.6 vs. 87.3 pg/mL,
p
= 0.010), phosphorylated tau (35.3 vs. 32.1 ng/mL,
p
= 0.035), and 1–42 beta amyloid (1134 vs. 830 pg/mL,
p
= 0.045). Despite effective antiretroviral treatment, blood brain barrier impairment persists in some HIV-positive patients: it is associated with markers of neuronal damage and it was not associated with CSF neopterin concentrations.
The second-generation of gravitational-wave detectors are just starting operation, and have already yielding their first detections. Research is now concentrated on how to maximize the scientific ...potential of gravitational-wave astronomy. To support this effort, we present here design targets for a new generation of detectors, which will be capable of observing compact binary sources with high signal-to-noise ratio throughout the Universe.
Although an increasing body of literature suggests a relationship between brain irradiation and deterioration of neurocognitive function, it remains as the standard therapeutic and prophylactic ...modality in patients with brain tumors. This review was aimed to abstract and evaluate the prediction models for radiation-induced neurocognitive decline in patients with primary or secondary brain tumors.
MEDLINE was searched on October 31, 2021 for publications containing relevant truncation and MeSH terms related to "radiotherapy," "brain," "prediction model," and "neurocognitive impairments." Risk of bias was assessed using the Prediction model Risk Of Bias ASsessment Tool.
Of 3,580 studies reviewed, 23 prediction models were identified. Age, tumor location, education level, baseline neurocognitive score, and radiation dose to the hippocampus were the most common predictors in the models. The Hopkins verbal learning (
= 7) and the trail making tests (
= 4) were the most frequent outcome assessment tools. All studies used regression (
= 14 linear,
= 8 logistic, and
= 4 Cox) as machine learning method. All models were judged to have a high risk of bias mainly due to issues in the analysis.
Existing models have limited quality and are at high risk of bias. Following recommendations are outlined in this review to improve future models: developing cognitive assessment instruments taking into account the peculiar traits of the different brain tumors and radiation modalities; adherence to model development and validation guidelines; careful choice of candidate predictors according to the literature and domain expert consensus; and considering radiation dose to brain substructures as they can provide important information on specific neurocognitive impairments.
Surface-enhanced Raman scattering (SERS) substrates were fabricated using electro-plating and e-beam lithography techniques. Nano-structures were obtained comprising regular arrays of gold ...nanoaggregates with a diameter of 80
nm and a mutual distance between the aggregates (gap) ranging from 10 to 30
nm. The nanopatterned SERS substrate enabled to have better control and reproducibility on the generation of plasmon polaritons (PPs). SERS measurements were performed for various proteins, namely bovine serum albumin (BSA), myoglobin, ferritin, lysozyme, RNase-B, α-casein, α-lactalbumin and trypsin. Principal component analysis (PCA) was used to organize and classify the proteins on the basis of their secondary structure. Cluster analysis proved that the error committed in the classification was of about 14%. In the paper, it was clearly shown that the combined use of SERS measurements and PCA analysis is effective in categorizing the proteins on the basis of secondary structure.
Children with cancer often undergo long treatment trajectories involving repeated needle procedures that potentially cause pain and distress. As part of a comprehensive effort to develop clinical ...practice guidelines (CPGs) to address pain prevention and management in children with cancer, we aimed to provide recommendations on the pharmacological and psychological management of procedure-related pain and distress.
Of the international inter-disciplinary CPG development panel (44 individuals), two working groups including 13 healthcare professionals focused on procedural pain and distress. Grading of Recommendations Assessment, Development and Evaluation methodology was used, including the use of systematic literature reviews to inform recommendations and the use of evidence to decision frameworks. At an in-person meeting in February 2018, the guideline panel discussed these frameworks and formulated recommendations which were then discussed with a patient-parent panel consisting of 4 survivors and 5 parents.
The systematic reviews led to the inclusion of 48 randomised controlled trials (total number of participants = 2271). Quality of evidence supporting the recommendations ranged from very low to moderate. Strong recommendations were made for the use of topical anesthetics in all needle procedures, for offering deep sedation (DS)/general anesthesia (GA) to all children undergoing lumbar puncture, for the use of DS/ GA in major procedures in children of all ages, for the use of hypnosis in all needle procedures and for the use of active distraction in all needle procedures.
In this CPG, an evidence-based approach to manage procedure-related pain and distress in children with cancer is presented. As children with cancer often undergo repeated needle procedures during treatment, prevention and alleviation of procedure-related pain and distress is of the utmost importance to increase quality of life in these children and their families.
•Children with cancer are often confronted with procedure-related pain and distress.•This clinical practice guideline provides recommendations to manage this.•Both pharmacological and psychological management strategies are discussed.•The international interdisciplinary panel adhered to Grading of Recommendations Assessment, Development and Evaluation methodology.
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