Ambient Room Light Research Articles

Time-gated scintillator imaging for real-time optical surface dosimetry in total skin electron therapy

The purpose of this study was to measure surface dose by remote time-gated imaging of plastic scintillators. A novel technique for time-gated, intensified camera imaging of scintillator emission was demonstrated, and key parameters influencing the signal were analyzed, including distance, angle and thickness. A set of scintillator samples was calibrated by using thermo-luminescence detector response as reference. Examples of use in total skin electron therapy are described. The data showed excellent room light rejection (signal-to-noise ratio of scintillation SNR ≈ 470), ideal scintillation dose response linearity, and 2% dose rate error. Individual sample scintillation response varied by 7% due to sample preparation. Inverse square distance dependence correction and lens throughput error (8% per meter) correction were needed. At scintillator-to-source angle and observation angle <50°, the radiant energy fluence error was smaller than 1%. The achieved standard error of the scintillator cumulative dose measurement compared to the TLD dose was 5%. The results from this proof-of-concept study documented the first use of small scintillator targets for remote surface dosimetry in ambient room lighting. The measured dose accuracy renders our method to be comparable to thermo-luminescent detector dosimetry, with the ultimate realization of accuracy likely to be better than shown here. Once optimized, this approach to remote dosimetry may substantially reduce the time and effort required for surface dosimetry.

Photo-enhanced antibacterial activity of ZnO/graphene quantum dot nanocomposites.

Synthesis of new, highly active antibacterial agents has become increasingly important in light of emerging antibiotic resistance. In the present study, ZnO/graphene quantum dot (GQD) nanocomposites were produced by a facile hydrothermal method and characterized by an array of microscopic and spectroscopic measurements, including transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis and photoluminescence spectroscopy. Antibacterial activity of the ZnO/GQD nanocomposites was evaluated with Escherichia coli within the context of minimum inhibitory concentration and the reduction of the number of bacterial colonies in a standard plate count method, in comparison to those with ZnO and GQD separately. It was found that the activity was markedly enhanced under UV photoirradiation as compared to that in ambient light. This was ascribed to the enhanced generation of reactive oxygen species under UV photoirradiation, with minor contributions from membrane damage, as manifested in electron paramagnetic resonance and fluorescence microscopic measurements. The results highlight the significance of functional nanocomposites based on semiconductor nanoparticles and graphene derivatives in the development of effective bactericidal agents.

The quality of fixed prosthodontic impressions: An assessment of crown and bridge impressions received at commercial laboratories

BackgroundThe authors evaluated and quantified clinically detectable errors commonly seen in impressions sent to commercial laboratories and determined possible relationships between finish line errors and other factors involved. MethodsThe authors visited 3 large and 1 small commercial dental laboratories over a 12-month period. Three calibrated examiners evaluated the impressions. The examiners evaluated all impressions for errors by using ×2.5 magnification loupes under ambient room lighting without the aid of additional illumination. ResultsThe authors evaluated 1,157 impressions; 86% of the examined impressions had at least 1 detectable error, and 55% of the noted errors were critical errors pertaining to the finish line. The largest single error categories evaluated were tissue over the finish line (49.09%), lack of unprepared stops in dual-arch impressions (25.63%), pressure of the tray on the soft tissue (25.06%), and void at the finish line (24.38%). The factors blood on the impression (odds ratio, 2.31; P < .001) and tray type (odds ratio, 1.68; P < .001) were associated significantly with finish line errors. ConclusionsMarginal discrepancies made up the largest category of error noted in impressions evaluated. The authors noted an increase in errors at the finish line with dual-arch impression techniques and in the presence of blood. Practical ImplicationsDentists have ethical, moral, and legal obligations bestowed on them by the profession and need to evaluate critically the work they send to laboratories. The authors strongly recommend an improvement in technique and reviewing of all impressions and working casts.

Optimization of fluorescent imaging in the operating room through pulsed acquisition and gating to ambient background cycling.

The design of fluorescence imaging instruments for surgical guidance is rapidly evolving, and a key issue is to efficiently capture signals with high ambient room lighting. Here, we introduce a novel time-gated approach to fluorescence imaging synchronizing acquisition to the 120 Hz light of the room, with pulsed LED excitation and gated ICCD detection. It is shown that under bright ambient room light this technique allows for the detection of physiologically relevant nanomolar fluorophore concentrations, and in particular reduces the light fluctuations present from the room lights, making low concentration measurements more reliable. This is particularly relevant for the light bands near 700nm that are more dominated by ambient lights.

Effects of diurnal, lighting, and angle-of-incidence variation on anterior segment optical coherence tomography (AS-OCT) angle metrics

BackgroundFirst reported study to assess the effect of diurnal variation on anterior chamber angle measurements, as well as, to re-test the effects of lighting and angle-of-incidence variation on anterior chamber angle (ACA) measurements acquired by time-domain anterior segment optical coherence tomography (AS-OCT).MethodsA total of 30 eyes from 15 healthy, normal subjects underwent anterior chamber imaging using a Visante time-domain AS-OCT according to an IRB-approved protocol. For each eye, the inferior angle was imaged twice in the morning (8 am – 10 am) and then again in the afternoon (3 pm – 5 pm), under light meter-controlled conditions with ambient room lighting ‘ON’ and lights ‘OFF’, and at 5° angle of incidence increments. The ACA metrics measured for each eye were: angle opening distance (AOD, measured 500 and 750 μm anterior from scleral spur), the trabecular-iris-space area (TISA, measured 500 and 750 μm anterior from scleral spur), and scleral spur angle. Measurements were performed by masked, certified Reading Center graders using the Visante’s Internal Measurement Tool. Differences in measurements between morning and afternoon, lighting variations, and angle of incidence were compared.ResultsMean age of the participants was 31.2 years (range 23–58). Anterior chamber angle metrics did not differ significantly from morning to afternoon imaging, or when the angle of incidence was offset by 5° in either direction away from the inferior angle 6 o’clock position. (p-value 0.13-0.93). Angle metrics at the inferior corneal limbus, 6 o’clock position (IC270), with room lighting ‘OFF’, showed a significant decrease (p < 0.05) compared to room lighting ‘ON’.ConclusionsThere does not appear to be significant diurnal variation in AS-OCT parameters in normal individuals, but lighting conditions need to be strictly controlled since variation in lighting led to significant variability in AS-OCT parameters. No changes in ACA parameters were noted by varying the angle-of-incidence, which gives confidence in being able to perform longitudinal studies in approximately the same area (plus/minus 5° of original scan location).

Can Lighting Influence Self-Disclosure?

With the advent of social networks where people disclose a lot of their information and opinions publicly, this research attempted to re-look at the effect of environmental lighting on willingness and actual disclosure of personal information. Previous literatures mostly addressed counseling setups and the findings were mixed. In order to clarify the effect of lighting on self-disclosure, two experiments were conducted with reported willingness to disclose (Experiment 1) as well as actual disclosure (Experiment 2) on a range of topics like social issues, body, money, work, and personality. While quite a handful of studies have reported differences in disclosure from very subtle environmental lighting manipulations, in both experiments we could not find any effect of ambient room lighting conditions on self-disclosure. These results call for caution both in over-interpreting subtle environmental effects and in increased generalization of perceptual metaphors to actual behavior.

Psychophysiological Effects of a Single, Short, and Moderately Bright Room Light Exposure on Mildly Depressed Geriatric Inpatients: A Pilot Study

Background: Light interventions typically exert their mood-related effects during morning bright light exposures over several weeks. Evidence about immediate ambient room light effects on depressed individuals is still sparse. Objective: The present study aimed at examining the acute effects of a single moderately bright room light exposure on mood, and behavioural and cardiac stress reactions of mildly depressed geriatric inpatients during a short cognitive stimulation and while resting. Methods: Twenty-one inpatients were tested in a balanced cross-over design on 2 consecutive days under either conventional room light (standard light) or artificial sunlight conditions for 30 min. Room illumination was implemented with an artificial skylight, which perfectly imitated solar indoor illumination (e.g., cloudless sky and bright artificial sun). Light-induced changes of mood, heart rate, and heart rate variability were recorded while performing a perseveration test (acted as cognitive stimulation) twice. Additionally, light-related behaviour was observed during a resting period between the cognitive tests and various subjective ratings were obtained. Results: Compared to standard light, exposure to artificial sunlight had a subjective calming effect over time (p = 0.029) as well as decreased heart rate and increased vagal tone (root mean squared of successive inter-beat intervals), both under cognitive workload and in resting conditions. Effect sizes of reported cardiac reactions were large. Cognitive variables were not influenced by light. Additionally, under the higher corneal illuminance of the artificial sunlight, patients perceived stronger glare (p = 0.030) and kept their eyes closed for longer times (p = 0.033) during the resting period. However, patients did not avoid bright light exposure while resting but voluntarily stayed within the area directly lit by the artificial sun nearly all the time (97%). Conclusion: To our knowledge, this study for the first time demonstrated immediate psychophysiological effects of a single, short room light exposure in mildly depressed geriatric inpatients during a short cognitive stimulation and while resting. The findings complement reported evidence on immediate alerting and mood-related effects of bright light exposures.

Leveraging Emerging Technologies and the “Internet of Things” to Improve the Quality of Cancer Care

Kevin Ashton coined the term “Internet of Things” in 2009 in the setting of supply chain management, but since that time, the Internet of Things (IoT) has had an impact on many other markets. Over the past several years, advances in computing and sensing have sparked the emergence of the IoT for health care. The IoT refers to a connection of smart objects such as appliances, sensors, controllers, wearables, andmedical devices to the Internet. Overall, the IoT health care market is predicted to grow from 32.4 billion in 2015 to 163 billion by the year 2020. In 2015, there were already 25 billion Internet-connected devices, which is double the number of humans on Earth. In addition, the number of IoT devices will have unprecedented growth and is expected to increase to more than 50 billion by 2020. Within the IoT, wearable devices and sensors alonewill grow tomore than 118 million devices predicted to be sold by 2018. As health care moves away from traditional encounterand office-based care paradigmstomorecontinuous interactions between the patient and the health care system, there is an unparalleled opportunity to leverage emerging technologies to create an ecosystem with the patient at the center. It is now possible to track various types of data in the patient’s own environment. Examples include accelerometer data (physical activity and intensity), temperature, heart rate and heart rate variability, blood pressure, sleep, caloric intake/expenditure, brain wave activity, pulse oximetry, glucose, and other biometric data. Wristbands and smartwatches currently predominate the fitness wearables market, but there will be a shift toward smart garments by 2020. There are also several ingestible and implantable sensors for tracking biometric data that already have or are currently undergoingUS Food andDrugAdministration approval. Beyond wearables, sensors can now be attached to appliances, objects, and the environment to detect carbon dioxide and carbon monoxide, particulate matter, ambient room temperature, light, and allergens such as pollen. Information technology was cited as a key requirement forbuildingahigh-quality cancer care delivery system by the Institute of Medicine and also as the foundation for a learning health care system. This vision for digitally capturing the health care experience for “real-time generation and application of knowledge for care improvement” has made substantial progress since that report in 2009. One exemplar is CancerLinQ, which is an initiative of the American Society of Clinical Oncology for aggregating and analyzing data from electronic health records, clinical trials, and clinical practice guidelines. Recently, CancerLinQ and the Cancer Informatics for Cancer Centers announced a collaboration to apply big data methodologies to drive discovery in cancer care. Understanding health care delivery through

Review of fluorescence guided surgery systems: identification of key performance capabilities beyond indocyanine green imaging.

There is growing interest in using fluorescence imaging instruments to guide surgery, and the leading options for open-field imaging are reviewed here. While the clinical fluorescence-guided surgery (FGS) field has been focused predominantly on indocyanine green (ICG) imaging, there is accelerated development of more specific molecular tracers. These agents should help advance new indications for which FGS presents a paradigm shift in how molecular information is provided for resection decisions. There has been a steady growth in commercially marketed FGS systems, each with their own differentiated performance characteristics and specifications. A set of desirable criteria is presented to guide the evaluation of instruments, including: (i) real-time overlay of white-light and fluorescence images, (ii) operation within ambient room lighting, (iii) nanomolar-level sensitivity, (iv) quantitative capabilities, (v) simultaneous multiple fluorophore imaging, and (vi) ergonomic utility for open surgery. In this review, United States Food and Drug Administration 510(k) cleared commercial systems and some leading premarket FGS research systems were evaluated to illustrate the continual increase in this performance feature base. Generally, the systems designed for ICG-only imaging have sufficient sensitivity to ICG, but a fraction of the other desired features listed above, with both lower sensitivity and dynamic range. In comparison, the emerging research systems targeted for use with molecular agents have unique capabilities that will be essential for successful clinical imaging studies with low-concentration agents or where superior rejection of ambient light is needed. There is no perfect imaging system, but the feature differences among them are important differentiators in their utility, as outlined in the data and tables here.

A modified protocol for rapid desensitization to chemotherapy agents

Desensitization protocols for chemotherapy agents (taxanes and platinum salts) have been extensively performed to safely administer these drugs to patients who have previously suffered a hypersensitivity reaction (HSR). Standardized protocols have been published using 12 or 16 steps to reach the cumulative dose in every patient. All these protocols were based on the preparation of 3 different solutions at 100-fold, 10-fold, and 1fold dilution of the final target concentration. However, from the pharmacological point of view, a reasonable doubt on the stability of diluted concentrations arises because there are no published data available. For example, concentrations higher than 0.2 and 0.1 mg/mL are known to be stable for paclitaxel and carboplatin, respectively, but no studies have been performed with lower concentrations. Docetaxel is the least stable drug. According to the Food and Drug Administration, a sodium chloride solution or 5% dextrose solution to produce a final docetaxel concentration of 0.3 to 0.74 mg/mL is stable for 4 hours under ambient room temperature and lighting conditions but there are no data for longer periods of time or lower concentrations. To address this potential problem of stability, a new protocol of desensitization with carboplatin and taxanes was developed. We present a proposed protocol that perfectly fits with the recommended published dosages for these chemotherapy agents but using the same solution during the whole procedure. Twelve patients with HSR to taxanes or platinum salts and for whom continued treatment with these drugs was considered advantageous were evaluated between July 2013 and April 2016. All patients were women with a median age of 50 years (range, 35-72 years) and had received antineoplastic treatment due to either ovarian and/or breast cancer. Eight of them had suffered at least 1 reaction with carboplatin and the remaining 4 with taxanes (2, paclitaxel and 2, docetaxel). Nine patients presented severe reactions involving the respiratory and/or the cardiovascular system. Most patients (11 of 12) presented with cutaneous symptoms (pruritus, flushing, or urticaria). During this period we have used different brands according to the availability at the hospital: docetaxel (Taxotere, Sanofi Aventis, Essex, United Kingdom; Docetaxel, Accord, Middlesex, United Kingdom; Docetaxel, Actavis, Devon, United Kingdom), carboplatin (Carboplatin, Pharmacia Nostrum, Madrid, Spain; Carboplatin, Accord, Middlesex, United Kingdom; Carboplatin, Kabi, Hampshire, United Kingdom), and paclitaxel (Taxol, Bristol Myers Squibb, Latina, Italy; Paclitaxel, Hospira, Madrid, Spain).

Visible-Light-Activated Bactericidal Functions of Carbon "Quantum" Dots.

Carbon dots, generally defined as small carbon nanoparticles with various surface passivation schemes, have emerged as a new class of quantum-dot-like nanomaterials, with their optical properties and photocatalytic functions resembling those typically found in conventional nanoscale semiconductors. In this work, carbon dots were evaluated for their photoinduced bactericidal functions, with the results suggesting that the dots were highly effective in bacteria-killing with visible-light illumination. In fact, the inhibition effect could be observed even simply under ambient room lighting conditions. Mechanistic implications of the results are discussed and so are opportunities in the further development of carbon dots into a new class of effective visible/natural light-responsible bactericidal agents for a variety of bacteria control applications.

Rose Bengal– and Riboflavin-Mediated Photodynamic Therapy to Inhibit Methicillin-Resistant Staphylococcus aureus Keratitis Isolates

To evaluate the invitro efficacy of rose bengal- and riboflavin-mediated photodynamic therapy for inhibition of methicillin-resistant Staphylococcus aureus (MRSA) isolates. Experimental study. Two different multidrug-resistant, clinical MRSA isolates were grown on nutrient agar, prepared in suspension, and adjusted to concentrations of 1.5× 10(4) colony-forming units per milliliter. Bacterial suspensions were mixed with rose bengal, riboflavin, or water according to experimental group. Tested in triplicate, groups included: Group I, MRSA control; Group II, MRSA with 0.1% rose bengal; Group III, MRSA with 0.03% rose bengal; and Group IV, MRSA with 0.1% riboflavin. All experimental groups were exposed to 3 lighting conditions: dark, ambient room light for 30minutes, and 5.4 J/cm(2) with either green light-emitting diode (LED) or ultraviolet-A (UV-A) irradiation. Plates were photographed at 72 hours and custom software measured bacterial growth inhibition. Complete growth inhibition of both MRSA strains was demonstrated (1) for both rose bengal concentrations under ambient and green LED irradiation, and (2) for the 0.1% rose bengal in the dark. The 0.03% rose bengal in dark conditions showed complete inhibition of strain 2 but incomplete inhibition of strain 1. Riboflavin showed almost complete inhibition with UV-A irradiation but demonstrated minimal inhibition for both strains in dark and ambient light conditions. Rose bengal- and riboflavin-mediated photodynamic therapy demonstrated complete growth inhibition invitro of 2 multidrug-resistant MRSA strains. Rose bengal was also effective in dark and ambient conditions. These results may have implications for invivo therapy.

Demonstration of the Spectrophotometric Complementary Color Wheel Using LEDs and Indicator Dyes

A quick, simple, and engaging demonstration of the spectrophotometric complementary color wheel is presented. Colored indicator dye solutions are illuminated under ambient room light and with different colors of light-emitting diodes (LEDs) in a dark room. The solutions are observed to be colored, black and opaque, or transparent and colorless in accordance with the color wheel, their optical absorption spectra, and the illumination conditions.

Real Time 3D Beam Visualization for Monitoring External Beam Radiation Therapy

The administration of radiation therapy has advanced steadily throughout its history. However, in spite of large advances in planning accuracy and motion tracking techniques, the actual administration of radiation continues to be a blind procedure. We propose that a system consisting of a flexible scintillation sheet and an array of digital cameras can be used to simultaneously visualize the patient surface and the delivered radiation beam in three dimensions and in real time. For the proof of concept system, scintillating sheets were made by mixing Gd2O2S:Tb (GOS) with silicone and casting the mixture into a thin sheet. The sheet was placed on a solid water phantom and irradiated with therapeutic photon beams from a medical linear accelerator (LINAC). The light emitted from the sheet was collected using a pair of cameras calibrated as a stereo pair. Custom designed image processing software was used to reconstruct the 3D scene and extract the beam profile. The shape and location of the extracted profile was compared to known collimator settings for validation. The system was capable of acquiring high quality images of both the phantom and the beam under various levels of ambient room lighting including those most commonly used during therapy. Images were obtained at a rate of 20 fps. The system demonstrated sub-millimeter resolution and accuracy in identifying both the shape and location of radiation beams. The intensity of the beam profile was found to be linear with dose rate and correlated to the expected surface dose as beam energy changes. A system consisting of digital cameras and a flexible scintillation sheet is capable of three dimensional visualization of external beam radiation therapy in real-time. The accuracy of the data is sufficient that further development of the system may provide the ability to verify the accuracy of treatment as it is occurring and provide a record for post-treatment analysis.

Using reaction time in visual search and decision making task to measure visual field thresholds in multifixation perimetry

PurposeThe ability to make eye movements to point the fovea toward object perceived in peripheral visual field is a fundamental feature of human visual system. We studied if reaction time (RT) in visual search task can be used for deciding if a peripheral visual field stimulus is visible when measuring visual field thresholds.MethodsOcusweep™ ambient light perimeter was programmed to display peripheral 0.2° stimulus of 100 ms duration for triggering a reflex saccade to point the fovea towards the location of the stimulus which was replaced with a faint arrow figure for reporting its direction with a button press and thus confirming foveal fixation. Next peripheral stimulus followed by a new arrow was then displayed. RT between button presses were recorded. Thresholds of the right eye of eight experienced healthy persons (mean age 43, range 22–58 years) using Humphrey 30–2 grid were measured with a staircase algorithm adjusting the intensity of the stimulus in response to the RT. Measurement reliability was estimated with catch trials, viewing distance controlled using ultrasonic rangers and variation in ambient room lighting (94–240 cd/m²) compensated using ambient light sensors of Ocusweep™.ResultsThresholds measured with RT perimetry were close to normal age corrected values of Octopus perimeter: mean MD was 0.7 dB and mean sLV 2.5 dB. The RT difference between positive (no stimulus, pure visual search, mean RT 1980 ms) and negative catch trials (suprathreshold stimulus, reflex saccade, mean RT 649 ms) was 1331 ms (SD 369 ms).ConclusionsReaction time perimetry can be used to measure visual field thresholds and also to assess reflex saccades.

Camera selection for real-time in vivo radiation treatment verification systems using Cherenkov imaging.

To identify achievable camera performance and hardware needs in a clinical Cherenkov imaging system for real-time, in vivo monitoring of the surface beam profile on patients, as novel visual information, documentation, and possible treatment verification for clinicians. Complementary metal-oxide-semiconductor (CMOS), charge-coupled device (CCD), intensified charge-coupled device (ICCD), and electron multiplying-intensified charge coupled device (EM-ICCD) cameras were investigated to determine Cherenkov imaging performance in a clinical radiotherapy setting, with one emphasis on the maximum supportable frame rate. Where possible, the image intensifier was synchronized using a pulse signal from the Linac in order to image with room lighting conditions comparable to patient treatment scenarios. A solid water phantom irradiated with a 6 MV photon beam was imaged by the cameras to evaluate the maximum frame rate for adequate Cherenkov detection. Adequate detection was defined as an average electron count in the background-subtracted Cherenkov image region of interest in excess of 0.5% (327 counts) of the 16-bit maximum electron count value. Additionally, an ICCD and an EM-ICCD were each used clinically to image two patients undergoing whole-breast radiotherapy to compare clinical advantages and limitations of each system. Intensifier-coupled cameras were required for imaging Cherenkov emission on the phantom surface with ambient room lighting; standalone CMOS and CCD cameras were not viable. The EM-ICCD was able to collect images from a single Linac pulse delivering less than 0.05 cGy of dose at 30 frames/s (fps) and pixel resolution of 512 × 512, compared to an ICCD which was limited to 4.7 fps at 1024 × 1024 resolution. An intensifier with higher quantum efficiency at the entrance photocathode in the red wavelengths [30% quantum efficiency (QE) vs previous 19%] promises at least 8.6 fps at a resolution of 1024 × 1024 and lower monetary cost than the EM-ICCD. The ICCD with an intensifier better optimized for red wavelengths was found to provide the best potential for real-time display (at least 8.6 fps) of radiation dose on the skin during treatment at a resolution of 1024 × 1024.

Changes in the objective amplitude of accommodation with pupil size.

We evaluate the effect of pupil size on objectively measured amplitude of accommodation (AA). Pupil diameter and wavefront aberrometry were obtained in 15 eyes when stimulus swept across the range of clear vision in steps of 0.5 diopters. Wavefront refraction techniques were used to compute objective AA as the maximum refractive change. Measurements were obtained monocularly under low and high ambient room lighting conditions with a fixed luminance of the fixation target. Amplitude of accommodation computations were performed taking into account just paraxial rays (paraxial AA) or including the effects of the change of spherical aberration during accommodation (minRMS AA). Mean pupil size values at low light level were 6.26 mm (relaxed) and 4.15 mm (maximum accommodation), whereas at the high light level, those values became 4.74 and 3.04 mm, respectively. The effects of both light level on accommodation were significant (p < 0.001), and accommodative miosis was slightly larger at low light levels. Mean minRMS and paraxial AA were always greater by more than 1 diopter in high than in low ambient lighting conditions (p < 0.01), indicating a significant impact of pupil size on AA. The influence of the ambient lighting on the objective AA is not only attributed to the increased effects of spherical aberration as the pupil dilates but mostly attributed to a decrease in the paraxial accommodation as pupil dilates.

Determining appropriate ambient lighting levels in Radiology reporting rooms

Determining appropriate ambient lighting levels in Radiology reporting rooms

Flicker-induced retinal arteriole dilation is reduced by ambient lighting.

To investigate the impact of ambient room lighting on the magnitude of flicker light-induced retinal vasodilations in healthy individuals. Twenty healthy nonsmokers participated in a balanced 2 × 2 crossover study. Retinal vascular imaging was performed with the dynamic vessel analyzer under reduced or normal ambient lighting, then again after 20 minutes under the alternate condition. Baseline calibers of selected arteriole and venule segments were recorded in measurement units. Maximum percentage dilations from baseline during 20 seconds of luminance flicker were calculated from the mean of three measurement cycles. Within-subject differences were assessed by repeated measures analysis of variance with the assumption of no carryover effects and pairwise comparisons from the fitted model. Mean (SD) maximum arteriole dilations during flicker stimulation under reduced and normal ambient lighting were 4.8% (2.3%) and 4.1% (1.9%), respectively (P = 0.019). Maximum arteriole dilations were (mean ± 95% confidence interval) 0.7% ± 0.6% lower under normal ambient lighting compared with reduced lighting. Ambient lighting had no significant effect on maximum venular dilations during flicker stimulation or on the baseline calibers of arterioles or venules. Retinal arteriole dilation in response to luminance flicker stimulation is reduced under higher ambient lighting conditions. Reduced responses with higher ambient lighting may reflect reduced contrast between the ON and OFF flicker phases. Although it may not always be feasible to conduct studies under reduced lighting conditions, ambient lighting levels should be consistent to ensure that comparisons are valid.

First Report of Race 2 of Colletotrichum trifolii Causing Anthracnose on Alfalfa (Medicago sativa) in Wisconsin.

Anthracnose of alfalfa (Medicago sativa), caused by Colletotrichum trifolii, is widespread in the United States. In addition to loss of forage due to death of stems, the pathogen causes crown rot, reducing stand life and winter survival (2), making it one of the most serious diseases of alfalfa. Three physiological races have been described (2). Race 1 is reported to be the dominant race that is present wherever alfalfa is grown, while race 2 was reported in a limited area in the Mid-Atlantic states, and race 4 was found in Ohio (1). Conspicuous, straw-colored dead stems with a "shepherd's crook" wilt and large, sunken, diamond-shaped lesions with a dark border were observed in experimental plots and breeding nurseries of experimental lines in Clinton and West Salem, WI, in August 2011 and in West Salem, WI, in mid-August 2012. Acervuli with black setae and orange spore masses were observed in lesions placed in moist chambers for 2 days at room temperature with ambient room lighting. Conidia were germinated on 1% water agar and then single hyphae were transferred to potato dextrose agar (PDA) plates. DNA was extracted from pure cultures of strains DA-1 (Clinton, WI) and FGI-3 (West Salem, WI), the rDNA ITS1-5.8S-ITS2 region was amplified with primers ITS1 (5'-TCCGTAGGTGAACCTGCGG-3') and ITS4 (5'-TCCTCCGCTTATTGATATGC-3'), the products sequenced directly, and the sequences compared to the ITS region of known race 1 and race 2 strains of C. trifolii. The sequences from DA-1 and FGI-3 were identical to the ITS sequence of C. trifolii 2sp2 (race 1; KF444778) and C. trifolii SB-2 (race 2; KF444779), but distinct from the ITS sequence of C. destructivum (JQ005764) and C. dematium (JX567507), which can cause anthracnose on alfalfa (1). Conidia from DA-1 and FGI-3 were harvested from 7-day-old cultures grown on PDA plates, diluted to 2 × 106 conidia/ml, and sprayed to runoff on 10-day-old growth chamber grown plants of three differential cultivars: Saranac (susceptible to races 1 and 2), Arc (resistant to race 1, susceptible to race 2), and Saranac AR (resistant to races 1 and 2). Plants were maintained at 100% relative humidity for 48 h and then grown in a growth chamber at 24°C with a 16-h photoperiod. Symptoms were rated at 14 days after inoculation. In the three repetitions of the experiment using 75 plants of each cultivar in each experiment, less than 10% of the Saranac and Arc plants survived, while survival of Saranac AR was 31 to 44%. The approximate expected survival of differential cultivars inoculated with race 1 is 1% for Saranac, 65 to 70% for Arc, and 45% for Saranac AR (2). Aggressiveness of race 2 strains on Saranac AR is variable, ranging from 12 to 68% plant survival (3). The susceptibility of Arc when inoculated with DA-1 and FGI-3 is consistent with the reaction to race 2 strains, indicating that both strains are race 2. The isolation of race 2 strains in major alfalfa growing regions in Wisconsin indicates that this physiological race is currently more widespread than previously observed. Although most modern alfalfa cultivars have resistance to race 1, few cultivars with resistance to race 2 are available. The occurrence of C. trifolii race 2 in the Midwest United States should be considered in alfalfa breeding programs when developing multi-pest resistant alfalfa cultivars.