Outdoor Lighting and the Effects of Artificial Light at Night (ALAN)

Kirmser Undergraduate Research Award - Individual Non-Freshman category, honorable mentionRoger FriedmannAs Light Emitting Diodes (LEDs) are replacing High Pressure Sodium (HPS) street lights, some groups have concerns about the health and environmental effects of blue-rich LED lights. The AMA released a report recommending that all street lighting have a CCT of less than 3000K, but other organizations felt this threshold was arbitrary and unfounded. To shed light on this dispute, I researched the effects of artificial light at night (ALAN), particularly concerning LED lights, to determine what policies design companies should set concerning outdoor lighting. I have learned that artificial light at night (ALAN) has been linked to many serious health conditions, including diabetes, cancer, heart disease, obesity, and depression. Light sources with high intensities of 450-500 nm light disrupt our bodies’ circadian rhythm and make it more difficult for our eyes to adjust to darkness. LEDs, even low-CCT LEDs, have a spike in intensity in that range. Studies have also shown that sources with high blue light content impact natural photosynthesis cycles, disrupt animal behavior, and affect skyglow and star visibility much more severely than warmer sources like HPS. Unfortunately, I also discovered that CCT, often the only metric that manufacturers release about the light source in a luminaire, is a poor descriptor of blue light content. On average, higher-CCT sources will have higher levels of blue light, but two sources with the same CCT can have wildly different levels of blue light, meaning that a designer cannot know the effects of the light source they choose. This presents a challenge and an opportunity for lighting designers. To provide exceptional design to clients, designers will need to be pioneers in calling for new light sources and metrics to describe spectral distribution, while continuing to serve their clients excellently with limited information

Three-Dimensional, Tomographic Super-Resolution Fluorescence Imaging of Serially Sectioned Thick Samples

Three-dimensional fluorescence imaging of thick tissue samples with near-molecular resolution remains a fundamental challenge in the life sciences. To tackle this, we developed tomoSTORM, an approach combining single-molecule localization-based super-resolution microscopy with array tomography of structurally intact brain tissue. Consecutive sections organized in a ribbon were serially imaged with a lateral resolution of 28 nm and an axial resolution of 40 nm in tissue volumes of up to 50 µm×50 µm×2.5 µm. Using targeted expression of membrane bound (m)GFP and immunohistochemistry at the calyx of Held, a model synapse for central glutamatergic neurotransmission, we delineated the course of the membrane and fine-structure of mitochondria. This method allows multiplexed super-resolution imaging in large tissue volumes with a resolution three orders of magnitude better than confocal microscopy

Understanding the rise of faculty-student coaching: an academic capitalism perspective

We examine the rise of coaching within management education to support student learning. We question the assumption that faculty-student coaching (FSC) is beneficial and propose that there may be some limitations in the use of FSC that have yet to be adequately acknowledged and discussed in the literature. In particular, we propose that there is currently insufficient evidence to conclude that coaching can produce knowledge acquisition and therefore ask why we persist in the use of FSC when we have limited evidence of its efficacy in delivering a core education outcome. We suggest that the theory of academic capitalism provides a useful, critical lens through which to view the growing trend in FSC, identifying that FSC may be utilized as a method of increasing student satisfaction, perceptions of value for money and as a useful marketing tool for business schools competing for students. However, academic capitalism may also explain the use of coaching via its ability to enhance the skills and attitudes of students, providing outcomes that are valued by students, employers and governments. We conclude our essay by providing recommendations to mitigate these proposed dangers and consequently maximise the effectiveness of coaching as a development tool in management education

Musculoskeletal and Cognitive Effects of a Movement Intervention During Prolonged Standing for Office Work

Objective: To investigate whether use of a movement intervention when undertaking prolonged standing affected discomfort and cognitive function. Background: Alternate work positions to break up prolonged sitting for office workers are being trialed, such as standing. Prolonged standing has potential negative health implications, including low back and lower limb discomfort, and may influence cognitive function. Introducing movement during standing may provide a healthy and productive alternative work posture. Method: Twenty adult participants undertook a laboratory study of 2 hr of standing and standing with movement (using a footrest) while performing computer work. Changes in discomfort and cognitive function, with muscle fatigue, low back angle, pelvis movement, lower limb swelling, and mental state, were investigated. Results: Discomfort increased significantly over time across all body regions. Ankle/foot differed between conditions (incident rate ratio [95% confidence interval]: 1.89 [1.10–3.23]), with higher discomfort during standing with movement. Creative problem-solving errors increased during standing with movement and decreased during standing (Time × Condition: ß = 0.64 [0.10–1.18]), with no other cognitive function measure differences. Mental state deteriorated over time for both conditions, greater during standing with movement (Time × Condition: ß = 2.44 [0.23–4.66]). No significant interaction effects were found for the other outcome variables. Conclusion: Standing with movement provided no advantage in discomfort or cognitive function. There were some negative effects for ankle/foot discomfort and creative problem solving. An alternate footrest design and protocol for use may yield more favorable results. Application: Based on the results from this study, footrest use to raise alternative foot for forced 5-min intervals would not be recommended to assist with managing discomfort while prolonged standing in workplaces

Unmasking group III metabotropic glutamate autoreceptor function at excitatory synapses in the rat CNS

Presynaptic group III metabotropic glutamate receptor (mGluR) activation by exogenous agonists (such as l-2-amino-4-phosphonobutyrate (l-AP4)) potently inhibit transmitter release, but their autoreceptor function has been questioned because endogenous activation during high-frequency stimulation appears to have little impact on synaptic amplitude. We resolve this ambiguity by studying endogenous activation of mGluRs during trains of high-frequency synaptic stimuli at the calyx of Held. In vitro whole-cell patch recordings were made from medial nucleus of the trapezoid body (MNTB) neurones during 1 s excitatory postsynaptic current (EPSC) trains delivered at 200 Hz and at 37°C. The group III mGluR antagonist (R,S)-cyclopropyl-4-phosphonophenylglycine (CPPG, 300 μm) had no effect on EPSC short-term depression, but accelerated subsequent recovery time course (τ: 4.6 ± 0.8 s to 2.4 ± 0.4 s, P= 0.02), and decreased paired pulse ratio from 1.18 ± 0.06 to 0.97 ± 0.03 (P= 0.01), indicating that mGluR activation reduced release probability (P). Modelling autoreceptor activation during repetitive stimulation revealed that as P declines, the readily releasable pool size (N) increases so that the net EPSC (NP) is unchanged and short-term depression proceeds with the same overall time course as in the absence of autoreceptor activation. Thus, autoreceptor action on the synaptic response is masked but the synapse is now in a different state (lower P, higher N). While vesicle replenishment clearly underlies much of the recovery from short-term depression, our results show that the recovery time course of P also contributes to the reduced response amplitude for 1–2 s. The results show that passive equilibration between N and P masks autoreceptor modulation of the EPSC and suggests that mGluR autoreceptors function to change the synaptic state and distribute metabolic demand, rather than to depress synaptic amplitude

A small pool of vesicles maintains synaptic activity in vivo

Chemical synapses contain substantial numbers of neurotransmitter-filled synaptic vesicles, ranging from approximately 100 to many thousands. The vesicles fuse with the plasma membrane to release neurotransmitter and are subsequently reformed and recycled. Stimulation of synapses in vitro generally causes the majority of the synaptic vesicles to release neurotransmitter, leading to the assumption that synapses contain numerous vesicles to sustain transmission during high activity. We tested this assumption by an approach we termed cellular ethology, monitoring vesicle function in behaving animals (10 animal models, nematodes to mammals). Using FM dye photooxidation, pHluorin imaging, and HRP uptake we found that only approximately 1–5% of the vesicles recycled over several hours, in both CNS synapses and neuromuscular junctions. These vesicles recycle repeatedly, intermixing slowly (over hours) with the reserve vesicles. The latter can eventually release when recycling is inhibited in vivo but do not seem to participate under normal activity. Vesicle recycling increased only to ≈5% in animals subjected to an extreme stress situation (frog predation on locusts). Synapsin, a molecule binding both vesicles and the cytoskeleton, may be a marker for the reserve vesicles: the proportion of vesicles recycling in vivo increased to 30% in synapsin-null Drosophila. We conclude that synapses do not require numerous reserve vesicles to sustain neurotransmitter release and thus may use them for other purposes, examined in the accompanying paper