Stacked volume holographic gratings for extending the operational wavelength range in LED and solar applications

A novel stacking procedure is presented for volume phase holographic gratings (VPHGs) recorded in photopolymer material using Corning Willow Glass as a flexible substrate in order to achieve broader angular and spectral selectivity in a diffractive device with high efficiency for solar and LED applications. For the first time to our knowledge, we have shown a device designed for use with a white LED that has the same input and output angles and high efficiency when illuminated by different wavelengths. In this paper, two VPHGs were designed, experimentally recorded, and tested when illuminated at normal incidence. The experimental approach is based on stacking two individual gratings in which the spatial frequency and slant have been tailored to the target wavelength and using real-time on-Bragg monitoring of the gratings in order to control the recorded refractive index modulation, thereby optimizing each grating efficiency for its design wavelength. Lamination of the two gratings together was enabled by using a flexible glass substrate (Corning Willow Glass). Recording conditions were studied in order to minimize the change in diffraction efficiency and peak diffraction angle during lamination and bleaching. The final fabricated stacked device was illuminated by a white light source, and its output was spectrally analyzed. Compared to a single grating, the stacked device demonstrated a twofold increase in angular and wavelength range. The angular and wavelength selectivity curves are in good agreement with the theoretical prediction for this design. This approach could be used to fabricate stacked lenses for white light LED or solar applications.

A randomized pilot study of mindfulness-based stress reduction in a young adult cancer sample: Feasibility, acceptability, and changes in patient reported outcomes

BACKGROUND

The primary purpose of this study was to examine the feasibility and acceptability of participation in a randomized waitlist-controlled intervention of mindfulness-based stress reduction (MBSR) in a young adult cancer sample. A secondary aim was to examine patterns of change in patient reported outcomes (PROs) of physical, social, and emotional functioning.

METHODS

Participants were enrolled at a large Midwestern comprehensive cancer center and randomized to MBSR or a waitlist control. Feasibility and acceptability were examined through enrollment metrics and a survey. PROs were gathered at baseline, 8-weeks, and 16-weeks. Descriptive statistics and mixed models were used in analyses.

RESULTS

Of 597 eligible participants, 151 (26.5%) consented from which 126 (83.4%) completed baseline measures. Sixty-seven participants were randomized to MBSR, and 59 to the waitlist. Immediately following MBSR, the majority of respondents (72%-78%) reported their experience with mindfulness was very logical and useful to increasing their wellbeing. Compared to waitlist members, MBSR participant's scores on PROs improved in expected directions.

CONCLUSIONS

Our findings suggest that recruitment for an intensive, in-person, multi-week supportive intervention can be challenging with young adults with cancer, similar to other cancer survivor populations; however once enrolled, feasibility and acceptability of MBSR was supported. Further, initial evidence on the role of MBSR on short-term changes in select PROs with this population was also demonstrated.

Autosomal Dominant Gene Negative Frontotemporal Dementia-Think of SCA17

SCA 17 is a rare, autosomal dominant disorder caused by TBP gene CAG/CAA repeat expansion. Ataxia and dementia are common. The presence of frontal dysfunction at outset of the disease may mimic frontotemporal dementia (FTD). Parkinsonism, chorea, dystonia, and pyramidal signs may occur. We report an Irish family with autosomal dominant partially penetrant frontal dementia with cerebellar atrophy due to SCA17 and present detailed neuropsychological assessment for the first time. A 44-year-old doctor presented with 18-month history of behavioral problems. She slowed down, became apathetic, and unable to multitask. She became more irritable and short tempered, and her work performance deteriorated. Brain MRI showed cerebellar atrophy and cerebellar hypometabolism was noted on FDG-PET. A sister developed personality changes at age 45 with apathy, and had problems with memory and social skills; another sister at age 39 became dysarthric and unsteady. A brother at age 52 demonstrated emotional lability, and became dysarthric, unsteady, and slowed down. Their mother aged 73 had an abnormal antalgic gait due to arthritis; their father was jocular and disinhibited. MAPT testing detected an exon 9 c.726C>T variant in the proband. Subsequent testing in nine siblings and both parents failed to show co-segregation with disease. SCA17 testing revealed a TBP gene 43 repeat expansion that co-segregated in all affected siblings and in the mother whose gait problems were initially attributed to arthritis. In over 80% of cases of FTD with clear autosomal dominant inheritance, causative gene defects involve MAPT, GRN, or C9orf72 mutations. A minority involves VCP, FUS, and CHMP2B. As evident from our case, SCA17 testing should also be considered, especially if cerebellar atrophy if found on imaging. Segregation analysis is crucial. MAPT variant (c.726C>T exon 9) detected in the family was deemed a polymorphism.

Impacting on factors promoting intra-group aggression in secure psychiatric settings

Three preliminary and linked studies investigate the impact of making alterations to factors considered relevant to engaging in and experiencing intra-group aggression (bullying) among adult male patients detained in a single secure forensic hospital. Study one (n = 44) outlines the institutional factors, attitudes towards bullying and environmental factors that increase the likelihood of engaging in bullying and/or being victimised. Study two (n = 53 patients and 167 staff) assesses the effect of three variations of intervention that aimed to reduce intra-group aggression through direct alteration of the physical and psychosocial environment, using data from both patients and staff. Study three (n = 414) looks at the effects of two variations of the intervention used in study two, which offered patients’ participation in individual and communal activities. It was predicted that changes to the physical and social environment would produce a reduction in the factors shown to predict intra-group aggression. Attitudes supportive of bullying and the presence of social hierarchies each increased the likelihood of engaging in bullying. Indirect changes to the social environment on the wards had more positive effects than those incorporating direct alterations to the physical and social environment. The differences in effectiveness of the two approaches are discussed in relation to the established predictors of intra-group aggression. The research concludes by noting the preliminary nature of the research and outlining potential directions for future research and intervention.

Dual-calibrated fMRI measurement of absolute cerebral metabolic rate of oxygen consumption and effective oxygen diffusivity

Dual-calibrated fMRI is a multi-parametric technique that allows for the quantification of the resting oxygen extraction fraction (OEF), the absolute rate of cerebral metabolic oxygen consumption (CMRO2), cerebral vascular reactivity (CVR) and baseline perfusion (CBF). It combines measurements of arterial spin labelling (ASL) and blood oxygenation level dependent (BOLD) signal changes during hypercapnic and hyperoxic gas challenges. Here we propose an extension to this methodology that permits the simultaneous quantification of the effective oxygen diffusivity of the capillary network (DC). The effective oxygen diffusivity has the scope to be an informative biomarker and useful adjunct to CMRO2, potentially providing a non-invasive metric of microvascular health, which is known to be disturbed in a range of neurological diseases. We demonstrate the new method in a cohort of healthy volunteers (n = 19) both at rest and during visual stimulation. The effective oxygen diffusivity was found to be highly correlated with CMRO2 during rest and activation, consistent with previous PET observations of a strong correlation between metabolic oxygen demand and effective diffusivity. The increase in effective diffusivity during functional activation was found to be consistent with previously reported increases in capillary blood volume, supporting the notion that measured oxygen diffusivity is sensitive to microvascular physiology.

Association between Type 1 Modic Changes and Propionibacterium Acnes Infection in the Cervical Spine: An Observational Study

BACKGROUND AND PURPOSE

Research on the association between Propionibacterium acnes in the disc space and type 1 Modic changes in adjacent vertebrae is limited and has produced mixed results. The prevalence of bacteria in intervertebral discs contradicts the prior understanding that skeletal areas in the human anatomy are sterile; yet it opens new treatment possibilities. We investigated the relationship of P acnes and type 1 Modic changes in the cervical spine.

MATERIALS AND METHODS

Over a 36-month period, we collected intraoperative biopsies of patients undergoing a routine cervical spine operation for degenerative disc diseases. The disc material was cultured aerobically and anaerobically for 7 days. All preoperative MR images were evaluated for Modic changes by a board-certified neuroradiologist. Medical records were reviewed for other spine interventions before the operation.

RESULTS

The study population consisted of 48 patients. Of these, 14 patients tested positive for P acnes (29%) at ≥1 level. Additionally, 13 patients had type 1 Modic changes (27%) at ≥1 level; 54% (95% CI, 27%-84%) of patients who had type 1 Modic changes were also positive for P acnes compared with 20% (95% CI, 7%-33%) of patients without type 1 Modic changes. The difference between these proportions was 34% (95% CI, 4%-64%). The Fisher exact test produced a P value of .03 for the association between P acnes and MC1, and .53 for the association between P acnes and prior procedures.

CONCLUSIONS

We conclude that P acnes was prevalent in the degenerated cervical spine and that type 1 Modic changes were predictive of a culture positive for P acnes. We also found that the prevalence of P acnes was not associated with previous interventions. If these results are validated by future studies, they could have a major impact on the standard of care for back and neck pain.

Investigation Of Interaction Between Physiological Signals And fMRI Dynamic Functional Connectivity Using Independent Component Analysis

The blood oxygen level dependent (BOLD) fMRI signal is influenced not only by neuronal activity but also by fluctuations in physiological signals, including respiration, arterial CO2 and heart rate/ heart rate variability (HR/HRV). Even spontaneous physiological signal fluctuations have been shown to influence the BOLD fMRI signal in a regionally specific manner. Consequently, estimates of functional connectivity between different brain regions, performed when the subject is at rest, may be confounded by the effects of physiological signal fluctuations. In addition, resting functional connectivity has been shown to vary with respect to time (dynamic functional connectivity - DFC), with the sources of this variation not fully elucidated. The effect of physiological factors on dynamic (time-varying) resting-state functional connectivity has not been studied extensively, to our knowledge. In our previous study, we investigated the effect of heart rate (HR) and end-tidal CO2 (PETCO2) on the time-varying network degree of three well-described RSNs (DMN, SMN and Visual Network) using mask-based and seed-based analysis, and we identified brain-heart interactions which were more pronounced in specific frequency bands. Here, we extend this work, by estimating DFC and its corresponding network degree for the RSNs, employing a data-driven approach to extract the RSNs (low-and high-dimensional Independent Component Analysis (ICA)), which we subsequently correlate with the characteristics of simultaneously collected physiological signals. The results confirm that physiological signals have a modulatory effect on resting-state, fMRI-based DFC.

Short- and long-term outcomes of patients with solid tumours following non-surgical intensive care admission

BACKGROUND

There has been a significant increase in the number of patients presenting with cancer related emergencies and potentially requiring critical care admission.

AIM

To analyse the short and long-term outcomes of patients with solid tumours requiring unplanned medical admission to a specialist cancer intensive care unit (ICU).

DESIGN

An unplanned cohort study.

METHODS

A retrospective analysis of patients admitted to a UK specialist tertiary oncology CCU between September 2009 and September 2015. The primary outcome measures were survival to CCU discharge and 1-year survival.

RESULTS

687 patients had an unplanned medical admission. The most frequent primary tumours were lymphoma (22.1%), lung (15.2%) and colorectal (13.0%), and 181 (44.4%) were known to have metastases. The median Acute Physiology and Chronic Health Evaluation (APACHE) II and Intensive Care National Audit and Research Centre (ICNARC) scores were 21 and 17, respectively. ICU mortality was 26.7%, with total hospital mortality of 41.9%. The median survival of the total cohort was 56 days after ICU admission, with 107 patients surviving 365 days. Patients with metastatic disease were almost twice as likely to die within the year following ICU admission compared with their counterparts without metastases. Only pancreatic and lung primaries were shown to have a statistically significant impact on survival at 1 year. Pneumonia carried with it the worst prognosis (cumulative survival 0.11), followed by sepsis (0.25) and non-infective respiratory disease (0.26).

CONCLUSIONS

The stage and type of cancer appear to have minimal impact on short-term ICU outcomes and only confer poorer long-term prognosis related to the disease.

Alterations in the metabolic and cardiorespiratory response to exercise in Huntington's Disease

BACKGROUND

Limited data suggests that an altered metabolic and cardiorespiratory exercise response may affect exercise performance in individuals with Huntington's disease (HD). There is no clear exploration of the response in individuals at different stages of the disease or in relation to genetic markers. This study aimed to examine the exercise response and recovery of HD participants, and the relationship to genetic and clinical markers.

METHOD

HD gene-positive participants (n = 31; 9 pre-manifest; 22 manifest HD) and a healthy control group (n = 29) performed an incremental exercise test until exhaustion. Performance, cardiorespiratory, metabolic and perceptual responses to exercise were determined from a maximal cycle ergometer test throughout the exercise test and during a recovery period.

RESULTS

During sub-maximal exercise, metabolic (lactate levels, oxygen uptake) and cardiorespiratory markers (heart rate) were elevated in HD participants compared to controls. Lactate elevation was specific to pre-manifest HD participants. Work capacity was reduced in both pre-manifest and manifest HD participants with tests terminated with no difference in metabolic, perceptual or cardiorespiratory markers. Submaximal oxygen uptake was correlated with motor score, whilst peak measures were unrelated to genetic or clinical markers. Heart rate recovery was attenuated in pre-manifest and manifest HD participants.

CONCLUSIONS

Our findings confirm metabolic and cardiorespiratory deficits reduce exercise performance and affect recovery from an early stage in HD, with submaximal deficits related to phenotypic expression. Exercise capacity appears to be limited by an altered movement economy, thus clinicians should consider an altered exercise response and recovery may affect prescription in HD.

Can 5-methylcytosine analogues with extended alkyl side chains guide DNA methylation?

5-Methylcytosine (^MeC) is an endogenous modification of DNA that plays a crucial role in DNA-protein interactions, chromatin structure, epigenetic regulation, and DNA repair. ^MeC is produced via enzymatic methylation of the C-5 position of cytosine by DNA-methyltransferases (DNMT) which use S-adenosylmethionine (SAM) as a cofactor. Hemimethylated CG dinucleotides generated as a result of DNA replication are specifically recognized and methylated by maintenance DNA methyltransferase 1 (DNMT1). The accuracy of DNMT1-mediated methylation is essential for preserving tissue-specific DNA methylation and thus gene expression patterns. In the present study, we synthesized DNA duplexes containing MeC analogues with modified C-5 side chains and examined their ability to guide cytosine methylation by the human DNMT1 protein. We found that the ability of 5-alkylcytosines to direct cytosine methylation decreased with increased alkyl chain length and rigidity (methyl > ethyl > propyl ∼ vinyl). Molecular modeling studies indicated that this loss of activity may be caused by the distorted geometry of the DNA-protein complex in the presence of unnatural alkylcytosines.