Cerebral microvascular physiology associated with white matter lesion burden differs by level of vascular risk in typically aging older adults.

White matter lesions (WMLs) are prevalent with aging, and higher WML burden has been observed in older adults with vascular diseases. While the physiology underlying the formation of WMLs is not known, various risk factors are associated with high WML burden. Here, we investigated the relationship between vascular risk factors and microvascular physiology (i.

Microlens Hollow-Core Fiber Probes for Operando Raman Spectroscopy.

We introduce a flexible microscale all-fiber-optic Raman probe which can be embedded into devices to enable operando in situ spectroscopy. The facile-constructed probe is composed of a nested antiresonant nodeless hollow-core fiber combined with an integrated high refractive index barium titanate microlens. Pump laser 785 nm excitation and near-infrared collection are independently characterized, demonstrating an excitation spot of full-width-half-maximum 1.

Transient gas-induced differential refractive index effects in as-drawn hollow core optical fibers.

When a hollow core fiber is drawn, the core and cladding holes within the internal cane geometry are pressurized with an inert gas to enable precise control over the internal microstructure of the fiber and counteract surface tension forces. Primarily by considering the temperature drop as the fiber passes through the furnace and the geometrical transformation of the internal microstructure from preform-to-fiber, we recently established that the gas pressure within the final 'as-drawn' fiber is substantially below atmospheric pressure. We have also established that slight changes in the gas refractive index within the core and surrounding cladding holes induced by changes in gas pressure are sufficient to significantly affect both the modality and loss of the fiber.

Double-Clad Antiresonant Hollow-Core Fiber and Its Comparison with Other Fibers for Multiphoton Micro-Endoscopy.

Label-free and multiphoton micro-endoscopy can transform clinical histopathology by providing an in situ tool for diagnostic imaging and surgical treatment in diseases such as cancer. Key to a multiphoton imaging-based micro-endoscopic device is the optical fiber, for distortion-free and efficient delivery of ultra-short laser pulses to the sample and effective signal collection. In this work, we study a new hollow-core (air-filled) double-clad anti-resonant fiber (DC-ARF) as a high-performance candidate for multiphoton micro-endoscopy.

Near-infrared radiation induced attenuation in nested anti-resonant nodeless fibers.

This Letter reports the first, to the best of our knowledge, spectral radiation induced attenuation (RIA) measurements of nested anti-resonant nodeless hollow-core fibers (NANFs). A 5-tube NANF, alongside a solid-core single-mode radiation resistant fiber (SM-RRF), was irradiated under γ-ray up to 101 kGy (SiO) and under x-ray up to 241 kGy (SiO). No RIA was observed in the NANF in the second half of the O-band, the S-band, the C-band, and the L-band.

Fiber-delivered heterodyne spectroscopy with a mid-infrared frequency comb.

By exploiting the excellent short-term phase stability between consecutive pulses from a free-running optical parametric oscillator frequency comb, we report the first example of hollow-core fiber-delivered heterodyne spectroscopy in the 3.1-3.8 µm wavelength range.

A prosocial value intervention in gateway STEM courses.

Many college students, especially first-generation and underrepresented racial/ethnic minority students, desire courses and careers that emphasize helping people and society. Can instructors of introductory science, technology, engineering, and math (STEM) courses promote motivation, performance, and equity in STEM fields by emphasizing the prosocial relevance of course material? We developed, implemented, and evaluated a prosocial utility-value intervention (UVI): A course assignment in which students were asked to reflect on the prosocial value of biology or chemistry course content; our focus was on reducing performance gaps between first-generation and continuing generation college students. In Studies 1a and 1b, we piloted two versions of a prosocial UVI in introductory biology ( = 282) and chemistry classes ( = 1,705) to test whether we could encourage students to write about the prosocial value of course content.

Sub-ppm gas phase Raman spectroscopy in an anti-resonant hollow core fiber.

We demonstrate recent progress in the development of a Raman gas sensor using a single cladding ring anti-resonant hollow core micro-structured optical fiber (HC-ARF) and a low power pump source. The HC-ARF was designed specifically for low attenuation and wide bandwidth in the visible spectral region and provided low loss at both the pump wavelength (532 nm) and Stokes wavelengths up to a Raman shift of 5000 cm. A novel selective core pressurization scheme was also implemented to further reduce the confinement loss, improving the Raman signal enhancement by a factor of 1.

Hundred-meter-scale, kilowatt peak-power, near-diffraction-limited, mid-infrared pulse delivery via the low-loss hollow-core fiber.

We report a high-power single-mode mid-infrared (MIR) pulse delivery system via anti-resonant hollow-core fiber (HCF) with a record delivery distance of 108 m. Near-diffraction-limited MIR light was transmitted by HCFs at wavelengths of 3.12-3.

Super-broadband on-chip continuous spectral translation unlocking coherent optical communications beyond conventional telecom bands.

Today's optical communication systems are fast approaching their capacity limits in the conventional telecom bands. Opening up new wavelength bands is becoming an appealing solution to the capacity crunch. However, this ordinarily requires the development of optical transceivers for any new wavelength band, which is time-consuming and expensive.

Hollow-core fiber delivery of broadband mid-infrared light for remote spectroscopy.

High-resolution multi-species spectroscopy is achieved by delivering broadband 3-4-μm mid-infrared light through a 4.5-meter-long silica-based hollow-core optical fiber. Absorptions from HCl, HCl, HO and CH present in the gas within the fiber core are observed, and the corresponding gas concentrations are obtained to 5-ppb precision using a high-resolution Fourier-transform spectrometer and a full-spectrum multi-species fitting algorithm.

Preliminary Effectiveness of a Remotely Monitored Blood Alcohol Concentration Device as Treatment Modality: Protocol for a Randomized Controlled Trial.

Background: Alcohol use disorder is a chronic disorder with a high likelihood of relapse. The consistent monitoring of blood alcohol concentration through breathalyzers is critical to identifying relapse or misuse. Smartphone apps as a replacement of or in conjunction with breathalyzers have shown limited effectiveness.

Self-Administered Gerocognitive Examination: longitudinal cohort testing for the early detection of dementia conversion.

Background: Significant cognitive changes as individuals' age are not being identified in a timely manner, delaying diagnosis and treatments. Use of brief, multi-domain, self-administered, objective cognitive assessment tools may remove some barriers in assessing and identifying cognitive changes. We compared longitudinal Self-Administered Gerocognitive Examination (SAGE) test scores to non-self-administered Mini-Mental State Examination (MMSE) scores in 5 different diagnostic subgroups.

Extruded tellurite antiresonant hollow core fiber for Mid-IR operation.

We report the first extruded tellurite antiresonant hollow core fibers (HC-ARFs) aimed at the delivery of mid-infrared (Mid-IR) laser radiation. The preform extrusion fabrication process allowed us to obtain preforms with non-touching capillaries in a single step, hence minimizing thermal cycles. The fibers were fabricated from in-house synthetized tellurite glass (containing Zn, Ba and K oxides) and co-drawn with a fluorinated ethylene propylene (FEP) polymer outer layer to improve their mechanical properties and protect the glass from humidity.

Fabrication of tubular anti-resonant hollow core fibers: modelling, draw dynamics and process optimization.

The fabrication of hollow core microstructured fibers is significantly more complex than solid fibers due to the necessity to control the hollow microstructure with high precision during the draw. We present the first model that can recreate tubular anti-resonant hollow core fiber draws, and accurately predict the draw parameters and geometry of the fiber. The model was validated against two different experimental fiber draws and very good agreement was found.

Laser frequency stabilization and spectroscopy at 2051 nm using a compact CO-filled Kagome hollow core fiber gas-cell system.

We describe a compact, all fiber, frequency stabilized diode laser system at 2051 nm using CO gas-filled Kagome Hollow Core Fiber (HCF), capable of tuning continuously over four transitions in CO: R(24), R(26), R(28), and R(30). This laser system has been designed for use in future space-based atmospheric monitoring using differential absorption lidar (DIAL). The fully spliced Kagome HCF gas cell is filled to 2 kPa CO partial pressure and we compare the observed CO lineshape features with those calculated using HITRAN, to quantify the properties of the CO-filled fiber cell.

Ethical Issues in Vascular Neurology.

There are ethical aspects to each of the three phases of cerebrovascular disease: hyperacute management, acute prognostication and management of early complications, and long-term recovery and reintegration with the community. This article addresses ethical concerns pertinent to each phase. First, we discuss ethical issues regarding consent for thrombolysis and endovascular treatment for acute ischemic stroke, including a review of considerations regarding the provision of acute stroke treatment advice over the telephone.

Nonlinear dynamic of picosecond pulse propagation in atmospheric air-filled hollow core fibers.

Atmospheric air-filled hollow core (HC) fibers, representing the simplest yet reliable form of gas-filled hollow core fiber, show remarkable nonlinear properties and have several interesting applications such as pulse compression, frequency conversion and supercontinuum generation. Although the propagation of sub-picosecond and few hundred picosecond pulses are well-studied in air-filled fibers, the nonlinear response of air to pulses with a duration of a few picoseconds has interesting features that have not yet been explored fully. Here, we experimentally and theoretically study the nonlinear propagation of ~6 ps pulses in three different types of atmospheric air-filled HC fiber.

Inflammatory demyelination alters subcortical visual circuits.

Background: Multiple sclerosis (MS) is an inflammatory demyelinating disease classically associated with axonal damage and loss; more recently, however, synaptic changes have been recognized as additional contributing factors. An anatomical area commonly affected in MS is the visual pathway; yet, changes other than those associated with inflammatory demyelination of the optic nerve, i.e.

Reach Out Churches: A Community-Based Participatory Research Pilot Trial to Assess the Feasibility of a Mobile Health Technology Intervention to Reduce Blood Pressure Among African Americans.

Innovative strategies are needed to reduce the hypertension epidemic among African Americans. Reach Out was a faith-collaborative, mobile health, randomized, pilot intervention trial of four mobile health components to reduce high blood pressure (BP) compared to usual care. It was designed and tested within a community-based participatory research framework among African Americans recruited and randomized from churches in Flint, Michigan.

HIV-1 Tat Inhibits Autotaxin Lysophospholipase D Activity and Modulates Oligodendrocyte Differentiation.

White matter injury has been frequently reported in HIV patients. Previous studies showed that HIV-1 Tat (transactivator of transcription), a viral protein that is produced and secreted by HIV-infected cells, is toxic to young, immature oligodendrocytes (OLGs). Adding Tat to the culture medium reduced the viability of immature OLGs, and the surviving OLGs exhibited reduced process networks.

Modal content in hypocycloid Kagomé hollow core photonic crystal fibers.

The modal content of 7 and 19 cell Kagomé anti resonant hollow core fibers (K-ARF) with hypocycloid core surrounds is experimentally investigated through the spectral and spatial (S) imaging technique. It is observed that the 7 and 19 cell K-ARF reported here, support 4 and 7 LP mode groups respectively, however the observation that K-ARF support few mode groups is likely to be ubiquitous to 7 and 19 cell K-ARFs. The transmission loss of the higher order modes (HOMs) was measured via S and a cutback method.

Expiratory Positive Airway Pressure for Sleep Apnea after Stroke: A Randomized, Crossover Trial.

Study Objectives: Obstructive sleep apnea (OSA) is common after stroke and predicts poor outcomes. Continuous positive airway pressure (CPAP) treats OSA but is generally poorly tolerated by stroke patients. We assessed whether nasal expiratory positive airway pressure (EPAP), an alternative to CPAP, may be an effective option after acute stroke.

Extracellular cues influencing oligodendrocyte differentiation and (re)myelination.

There is an increasing number of neurologic disorders found to be associated with loss and/or dysfunction of the CNS myelin sheath, ranging from the classic demyelinating disease, multiple sclerosis, through CNS injury, to neuropsychiatric diseases. The disabling burden of these diseases has sparked a growing interest in gaining a better understanding of the molecular mechanisms regulating the differentiation of the myelinating cells of the CNS, oligodendrocytes (OLGs), and the process of (re)myelination. In this context, the importance of the extracellular milieu is becoming increasingly recognized.