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"Anderson, Zachary"
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Realization of an all-dielectric zero-index optical metamaterial
Metamaterials offer unprecedented flexibility for manipulating the optical properties of matter, including the ability to access negative index
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,
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,
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,
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, ultrahigh index
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and chiral optical properties
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,
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,
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. Recently, metamaterials with near-zero refractive index have attracted much attention
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,
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,
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,
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,
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. Light inside such materials experiences no spatial phase change and extremely large phase velocity, properties that can be applied for realizing directional emission
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,
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,
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, tunnelling waveguides
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, large-area single-mode devices
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and electromagnetic cloaks
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. However, at optical frequencies, the previously demonstrated zero- or negative-refractive-index metamaterials have required the use of metallic inclusions, leading to large ohmic loss, a serious impediment to device applications
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,
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. Here, we experimentally demonstrate an impedance-matched zero-index metamaterial at optical frequencies based on purely dielectric constituents. Formed from stacked silicon-rod unit cells, the metamaterial has a nearly isotropic low-index response for transverse-magnetic polarized light, leading to angular selectivity of transmission and directive emission from quantum dots placed within the material.
Previously demonstrated zero- or negative-refractive-index metamaterials at optical frequencies suffer from large ohmic losses because of the need to use metals. Metamaterials formed by stacked silicon rod unit cells allow the realization of all-dielectric impedance-matched zero-index metamaterials operating at optical frequencies, potentially benefiting the development of angular-selective optical devices.
Journal Article
A rapid method for assessing the accumulation of microplastics in the sea surface microlayer (SML) of estuarine systems
Microplastics are an increasingly important contaminant in the marine environment. Depending on their composition and degree of biofouling, many common microplastics are less dense than seawater and so tend to float at or near the ocean surface. As such, they may exhibit high concentrations in the sea surface microlayer (SML – the upper 1–1000 μm of the ocean) relative to deeper water. This paper examines the accumulation of microplastics, in particular microfibres, in the SML in two contrasting estuarine systems – the Hamble estuary and the Beaulieu estuary, southern U.K., via a novel and rapid SML-selective sampling method using a dipped glass plate. Microplastic concentrations (for identified fibres, of 0.05 to 4.5 mm length) were highest in the SML-selective samples (with a mean concentration of 43 ± 36 fibres/L), compared to <5 fibres/L for surface and sub-surface bulk water samples. Data collected show the usefulness of the dipped glass plate method as a rapid and inexpensive tool for sampling SML-associated microplastics in estuaries, and indicate that microplastics preferentially accumulate at the SML in estuarine conditions (providing a potential transfer mechanism for incorporation into upper intertidal sinks). Fibres are present (and readily sampled) in both developed and more pristine estuarine systems.
Journal Article
Cerebrospinal Fluid Concentrations of Calcitonin Gene Related Peptide in Dogs With Chiari‐Like Malformation
ABSTRACT
Background
The biomarker Calcitonin Gene‐Related Peptide (CGRP) is elevated in human conditions associated with neuropathic pain, but has not yet been studied in Cavalier King Charles Spaniels (CKCS) with Chiari‐like malformation (CM).
Hypothesis/Objectives
Cavalier King Charles Spaniels with clinical signs of CMSM would have higher CSF concentrations of CGRP than asymptomatic CKCS. Our aim was to measure CSF CGRP concentrations in CKCS with and without clinical signs of CMSM.
Animals
Twenty‐nine CKCS drawn from research and clinical cases underwent quantification of pain and scratching, a brain and spinal cord MRI, and lumbar CSF collection.
Methods
This was a prospective study with both normal and clinically affected CKCS recruited. The CSF concentration of CGRP (C‐CGRP) was measured using an ELISA assay. Dogs were grouped by the presence of SM, pain, and scratching, and concentrations of C‐CGRP were compared between groups using Wilcoxon Rank Sum. The concentration of C‐CGRP, pain score, and SM diameter were evaluated using linear regression.
Results
Concentration of C‐CGRP was significantly higher in painful dogs (median 116.1, range: 11.6–238.3 pg/mL) as compared to non‐painful dogs (median 77.7 pg/mL, range 0–266.2 pg/mL; p = 0.0124). No significant difference in C‐CGRP concentration was noted between dogs with (median 99.3, range 0–226.6 pg/mL) and without (median 102.2, range 6.0–266.2 pg/mL) SM (p = 0.305).
Conclusions and Clinical Importance
Cerebrospinal fluid CGRP concentration is elevated in CKCS exhibiting pain regardless of the presence of SM. CGRP might contribute to neuropathic pain in CMSM and could be a target for therapeutic intervention.
Journal Article
A randomized, controlled clinical trial demonstrates improved owner-assessed cognitive function in senior dogs receiving a senolytic and NAD+ precursor combination
Age-related decline in mobility and cognition are associated with cellular senescence and NAD + depletion in dogs and people. A combination of a novel NAD + precursor and senolytic, LY-D6/2, was examined in this randomized controlled trial. Seventy dogs with mild to moderate cognitive impairment were enrolled and allocated into placebo, low or full dose groups. Primary outcomes were change in cognitive impairment measured with the owner-reported Canine Cognitive Dysfunction Rating (CCDR) scale and change in activity measured with physical activity monitors. Fifty-nine dogs completed evaluations at the 3-month primary endpoint, and 51 reached the 6-month secondary endpoint. There was a significant difference in CCDR score across treatment groups from baseline to the primary endpoint (p = 0.02) with the largest decrease in the full dose group. No difference was detected between groups using in house cognitive testing. There were no significant differences between groups in changes in measured activity. The proportion of dogs that improved in frailty and owner-reported activity levels and happiness was higher in the full dose group than other groups, however this difference was not significant. Adverse events occurred equally across groups. All groups showed improvement in cognition, frailty, and activity suggesting placebo effect and benefits of trial participation. We conclude that LY-D6/2 improves owner-assessed cognitive function over a 3-month period and may have broader, but more subtle effects on frailty, activity and happiness as reported by owners.
Journal Article
No group differences in Traditional Economics Measures of loss aversion and framing effects in bipolar I disorder
Bipolar disorder (BD) is associated with impaired decision making, yet few studies have adopted paradigms from behavioral economics to decompose which, if any, aspects of decision making may be impacted. This may be particularly relevant for decision-making processes relevant to known difficulties with emotive dysfunction and corresponding reward dysregulation in BD. Participants with bipolar I disorder (BD;
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= 44) and non-psychiatric healthy controls (CTL;
n
= 28) completed three well-validated behavioral economics decision making tasks via a remote-based survey, including loss aversion and framing effects, that examined sensitivity to probabilities and potential gains and losses in monetary and non-monetary domains. Consistent with past work, we found evidence of moderate loss aversion and framing effects across all participants. No group differences were found in any of the measures of loss aversion or framing effects. We report no group differences between bipolar and non-psychiatric groups with respect to loss aversion and framing effects using a remote-based survey approach. These results provide a framework future studies to explore similar tasks in clinical populations and suggest the context and degree to which decision making is altered in BD may be rooted in a more complex cognitive mechanism that warrants future research.
Journal Article
Pregnancy following assisted reproductive technology in morbidly obese patients: assessment of feto-maternal outcomes
PurposeTo examine feto-maternal characteristics and outcomes of morbidly obese pregnant patients who conceived with assisted reproductive technology (ART).MethodsThis cross-sectional study queried the Healthcare Cost and Utilization Project’s National Inpatient Sample. Study population was 48,365 patients with ART pregnancy from January 2012 to September 2015, including non-obesity (n = 45,125, 93.3%), class I–II obesity (n = 2445, 5.1%), and class III obesity (n = 795, 1.6%). Severe maternal morbidity at delivery per the Centers for Disease and Control Prevention definition was assessed with multivariable binary logistic regression model.ResultsPatients in the class III obesity group were more likely to have a hypertensive disorder (adjusted-odds ratio (aOR) 3.03, 95% confidence interval (CI) 2.61–3.52), diabetes mellitus (aOR 3.08, 95%CI 2.64–3.60), large for gestational age neonate (aOR 3.57, 95%CI 2.77–4.60), and intrauterine fetal demise (aOR 2.03, 95%CI 1.05–3.94) compared to those in the non-obesity group. Increased risks of hypertensive disease (aOR 1.35, 95%CI 1.14–1.60) and diabetes mellitus (aOR 1.39, 95%CI 1.17–1.66) in the class III obesity group remained robust even compared to the class I–II obesity group. After controlling for priori selected clinical, pregnancy, and delivery factors, patients with class III obesity were 70% more likely to have severe maternal morbidity at delivery compared to non-obese patients (8.2% vs 4.4%, aOR 1.70, 95%CI 1.30–2.22) whereas those with class I–II obesity were not (4.1% vs 4.4%, aOR 0.87, 95%CI 0.70–1.08).ConclusionsThe results of this national-level analysis in the United States suggested that morbidly obese pregnant patients conceived with ART have increased risks of adverse fetal and maternal outcomes.
Journal Article