Measurement of Lepton-Jet Correlation in Deep-Inelastic Scattering with the H1 Detector Using Machine Learning for Unfolding.

The first measurement of lepton-jet momentum imbalance and azimuthal correlation in lepton-proton scattering at high momentum transfer is presented. These data, taken with the H1 detector at HERA, are corrected for detector effects using an unbinned machine learning algorithm (multifold), which considers eight observables simultaneously in this first application. The unfolded cross sections are compared with calculations performed within the context of collinear or transverse-momentum-dependent factorization in quantum chromodynamics as well as Monte Carlo event generators.

Determination of the strong coupling constant α s ( m Z ) in next-to-next-to-leading order QCD using H1 jet cross section measurements: H1 Collaboration.

The strong coupling constant α s is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of α s ( m Z ) at the Z-boson mass m Z are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be α s ( m Z ) = 0.1157 ( 20 ) exp ( 29 ) th . Complementary, α s ( m Z ) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value α s ( m Z ) = 0.1142 ( 28 ) tot obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.

Human tear glucose.

By means of a photometric method, the glucose concentrations of 875 human tear samples were analyzed. The arithmetic mean for the total population was 7.5 mg/dl, although significant differences in average concentration among individuals were found (3.4 to 12.7 mg/dl). Although the total population mode, 3.2 mg/dl, did fall within range limits often cited in the current literature, the higher arithmetic mean found here is attributed to special precautions taken to minimize reflex tear inclusion, to corrections made for effects of processing delay, and to the assembly of more extensive and time-balanced sample bases (an average of 73 specimens taken hourly throughout the waking periods of 5 days) for each individual studied. The population diurnal profile (i.e., the average of 60 individual profile days constructed here) was found to have some phase characteristics resembling those of serum glucose population profiles in the literature.

Ganzfeld blankout occurs in bowl perimetry and is eliminated by translucent occlusion.

An intermittent darkening of the visual field (ganzfeld "blankout") is perceived during bowl perimetry. Since this may be a form of rivalry, we hypothesized that occluding the nontested eye with a translucent occluder may eliminate the phenomenon. Ten normal subjects underwent visual field testing with both a translucent and an opaque occluder. Eight of the 10 reported darkening to occur with the opaque patch, while none reported it with the translucent occluder. The darkening occurred with a mean latency of 10.9 seconds, occupied 34.4% of the time, and on average occurred 3.25 times per minute. With the translucent occluder, retest threshold variability was 18.8% less and sensitivity was increased by 0.7 dB. The elimination of this darkening using translucent occluders in bowl perimetry will allow reduced variability and increased sensitivity and comfort.

Pupillary micro movements apparently related to pulse frequency.

Pupillary micro changes in diameter apparently related to pulse frequency are superimposed on the larger fluctuations called the pupillary unrest. This small component of the pupillary unrest waxes and wanes with each pulsation of the blood. The effect was found to vary inversely with the average pupil diameter which can be controlled by making the eye accommodate or allowing more or less light to enter the eye.

A performance evaluation study of three types of alpha-track detector radon monitors.

Three models of alpha-track detector (ATD) Rn monitors were exposed in Environmental Protection Agency (EPA) Rn chambers to obtain estimates of precision and bias for the National Residential Radon Survey (NRRS). Exposures in this study ranged from 37 to 740 Bq y m-3 (1 to 20 pCi y L-1), plus blanks. These exposures correspond to the range expected in most U.S. residences. All detectors were purchased through a Rn mitigation firm to assure that the vendors did not give special attention to the ATDs used in this study. Ten ATDs of each model were studied at 12 exposures. The mean and standard deviation of the reported values for each model were calculated and compared with the continuously monitored chamber concentrations to determine the bias and precision at each exposure. Results of this analysis were discussed with the vendors, who took corrective actions. Changes in track counting procedures and calibrations improved detector performance. Readings of one detector were adjusted based on a regression of the monitored values on the reported values.

Motorist vision policy.

BACKGROUND: The primary purpose of public policy requiring vision testing for driver license renewal is to identify individuals with functional vision impairments and, when necessary, to restrict their driving. This is based on the presumption that poor vision is causally related to poor driving and traffic crashes. METHODS: The AOA Environmental and Occupational Vision Committee performed a synthesis of relevant empirical literature on policy-based research and developed potential options for enhancing traffic safety. RESULTS: Presently, some states require vision testing for driver's license renewal and some do not. Regional and nationwide studies report that vision-related license renewal policies are associated with enhanced traffic safety. However, contemporary vision screening tests may be of limited value in identifying individuals with functional vision impairments. CONCLUSION: The most cost-effective and valid method for identifying, treating and counseling visually impaired drivers is to require a comprehensive eye examination as a condition for driver license renewal for those with a high prevalence or high probability of vision impairment.

Prevención de síntomas visuales y músculo-esqueléticos asociados al uso de ordenador en el trabajo / Workplace interventions to prevent musculoskeletal and visual symptoms and disorders among computer users: A systematic review

Antecedentes: La literatura científica sobre el efecto de las intervenciones en el puesto de trabajo, en la compensación de un defecto refractivo y en la conducta sobre los síntomas músculo-esqueléticos y visuales en los usuarios de ordenador, es amplia y heterogénea. Método: Se realizó una revisión sistemática de la literatura como la mejor síntesis de la evidencia para abordar la siguiente cuestión general: ¿Tienen las intervenciones en trabajadores de oficina que son usuarios de ordenador un efecto sobre la salud músculo-esquelética o visual? También se realizó una evaluación de intervenciones específicas. Resultados: La búsqueda inicial identificó 7.313 artículos que se redujeron a 31 estudios tras analizar contenido y calidad. En general, se observó un nivel mixto de evidencia para la pregunta general. Se observó una evidencia moderada de que: (1) la adaptación de los puestos de trabajo no tenía ningún efecto, (2) tampoco la realización de descansos y ejercicio y (3) utilizar dispositivos alternativos a los ratones convencionales sí tenía un efecto positivo. Para el resto de intervenciones se observó una evidencia del efecto mixta o insuficiente. Conclusión: Se encontraron pocos estudios de alta calidad que examinaran los efectos de las intervenciones en oficinas sobre los problemas musculo-esqueléticos y de la salud visual

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Double-blind placebo-controlled examination of timing effects in the training of positive vergences.

The purpose of this study was to document the effects of positive fusional vergence therapy and to determine the most effective timing of such training. Four experimental protocols were selected and five subjects were assigned randomly to each of the four experimental groups. Each subject in each group spent 120 min (total) over a period of 3 weeks doing positive fusional vergence training. Group A trained in twelve 10-min sessions; group B in six 20-min sessions; and group C in three 40-min sessions. Group D was a control group. All the training was in-office and consisted of positive fusional vergence training on the synoptophore. Each of the test groups showed increases in their positive fusional vergence ability at both distance and near. Group A (shorter sessions) demonstrated the largest increases overall. In addition, the group which trained in short 10-min sessions (Group A) was the only one which showed significant increases in the negative fusional vergences and the positive blur finding. I conclude that it is best to use short, frequent training sessions to increase the amplitude of positive fusional vergence. The results and implications of the study are discussed briefly.

Characteristics of exodeviations: I. A comparison of three classes.

A retrospective study of 179 patients (69 males and 110 females) with binocular visual dysfunction and an exodeviation at distance or near or at both distances has been completed. The mean age of 19.7 years was significantly younger than the population from which they were referred. The patients were classed as convergence insufficiency, equal exodeviation, or divergence excess, based on the relation of the distance and near angles of deviation. Based on these criteria, interaction was found to be present between the diagnostic class and the frequency of the deviation, the symptoms reported, and a variety of clinical parameters such as the angles of deviation at distance and near, the AC/A ratio, positive and negative vergence values, the amplitude of accommodation, and the threshold of stereopsis. A number of statistical relations were noted between the frequency of the deviation vs. the symptoms reported and a variety of the clinical parameters. The implications of these results are discussed.

Characteristics of exodeviations: II. Changes with treatment with orthoptics.

This study examined retrospectively the records of 179 patients who had binocular visual dysfunction as a result of an exodeviation (either at distance or near or both). The patients were classified as having convergence insufficiency (N = 110), equal exodeviations (N = 49), or divergence excess (N = 18). The diagnostic groups and the different frequencies of deviation reacted differently to treatment with a standard orthoptic regimen. Nearly all the patients (97%) achieved some improvement in either objective or subjective areas or both. However, fewer were able to satisfy the criteria set for total success. Factors correlated with the success of the treatment were the initial angle of deviation at distance and the initial level of stereopsis. The results and implications of this study are discussed.

Negative vergence training in humans.

Two healthy subjects (male and female, ages 22 and 25 years) spent 50 h over a period of 7 consecutive weeks training the negative vergence system. The training was performed in two 45-min daily sessions, usually immediately before and after the workday. The training was exclusively negative vergence training using devices such as variable vectograms, the aperture rule, the synoptophore, and loose or bar prisms. An extensive examination of the visual systems before, after, and periodically during the training demonstrated that the negative vergences increased at distance by 5.0 delta and at near by 9.1 delta (using hand-held prisms, bar prisms, and the synoptophore). The phorias of both subjects became more exophoric or less esophoric at both distance and near by 3.6 delta (using average of changes on the cover test, von Graefe subjective phoria technique, and the synoptophore). A haploscope equipped with a coincidence optometer showed only small increases in vergence amplitude but confirmed that the lag of accommodation became more stable after the training than it was before. Other testing suggested that the negative relative accommodation, the angle of deviation at both distance and near, positive vergences, the associated phoria, and the slope of the fixation disparity curve changed significantly over the period of training. I conclude that negative vergence training can increase the negative vergence capabilities and also affect the phoria position of the eyes via feed-back into the slow vergence system.

Characteristics of convergence insufficiency.

Convergence insufficiency (CI) is a well-known syndrome of binocular visual dysfunction. In a review of 58 papers, considerable variation was noted in the criteria used to define the condition. Symptoms and decreased positive fusional vergences (both at the nearpoint) were the only criteria named in more than one-half of the studies. An extended nearpoint of convergence (NPC) and increased exophoria at near were criteria in about one-third of the papers. Examination of data in the reviewed papers shows that although considerable variability was noted, the distance exodeviation, distance negative vergences, visual acuity, refraction, and stereopsis were about the same as population norms. Positive vergences, negative vergence at near, and NPC were somewhat less than population norms. Vergences relative to Sheard's criterion, the near exophoria, accommodative amplitude, and the AC/A ratio were consistently below those derived from population norms. This considerable variation may largely be a result of different criteria used for diagnosis, subpopulations within the data, and other confounding factors.

Analysis of seven methods of measuring the angle of deviation.

The correlations between seven methods of measuring the angle of deviation were assessed in two groups of subjects. Group 1 consisted of 343 subjects with normal binocular vision. Group 2 was made up of 18 subjects with strabismus. The correlation coefficients (r) between various testing procedures varied significantly in the two groups. Group 1 could be separated into three levels of correlation and group 2 could be separated into two levels of correlation based on the 95% confidence limits of the correlation coefficients. Significant differences also could be demonstrated in the average measured values of the angle of deviation of group 1, while the second group was indistinguishable at the 5% significance level using a one-way analysis of variance procedure. These data are briefly discussed in light of their clinical implications.

Characteristics of a video-type pupillometer.

In using a video-type pupillometer, the adjustment of the clipping level, the illumination of the target, the focus of the camera, and the viewing angle have been shown to affect the measurement. The focus of the camera and the viewing angle are the most important variables. The precision of this instrument can be as good as 0.01 mm. The accuracy of the instrument is good with regard to clinical standards; however, all measurements vary slightly from the known value. Interexaminer variation appears to be small.

Accommodative insufficiency.

A retrospective review of the records of 96 patients with accommodative insufficiency has been completed. In addition to the major sign of reduced accommodative amplitude for their ages, I often found a reduction in the facility of accommodation, a smaller lag of accommodation, a tendency toward convergence insufficiency, slightly reduced fusional vergence and stereopsis, and a reduced nearpoint of convergence. Suppression was not generally found. The results of orthoptic exercises and/or a plus lens addition at near were examined. Most patients (90%) obtained some relief with treatment. About 53% had their objective and subjective problems totally solved during an average treatment period of 3.7 weeks. I determined the characteristics of the patients before and after treatment. The current state of the treatment of accommodative insufficiency is discussed.

Accommodative dysfunction.

A retrospective review of the records of 114 subjects with accommodative dysfunction has been completed. Most subjects (N = 96) were found to have accommodative insufficiency. Lesser numbers of subjects were categorized in the class of infacility of accommodation (N = 14), spasm of accommodation (N = 3) and fatigue of accommodation (N = 1). A majority of the subjects presented with complaints of blur, headaches and/or asthenopia while attempting nearwork. Most subjects presented with reduced abilities in one or more of the following areas: accommodative amplitude and facility, fusional vergences, near point of convergence and stereo acuities. The clinical characteristics of the group as a whole and the major subgroups have been examined both before and after treatment of the condition with orthoptic exercises and/or plus lenses at the nearpoint. The result of the treatment indicates that although most subjects (96%) experienced some relief with treatment only about half (53%) had their problems totally solved. The importance of these findings is briefly discussed.

A comparison of the results of tonic and phasic vergence training.

Thirty-four healthy asymptomatic young adults were randomly divided into two groups. All subjects underwent training aimed at expanding the vergence ranges. The training in one group consisted of tasks emphasizing smooth, slow activities. The other group trained using quicker, stepwise, more phasic tasks. The vergence ranges were subjectively measured using a small (1.72 degree diameter) target in a major amblyoscope. The study lasted 6 weeks. The first 3 weeks served as a control period over which time the vergences proved to be stable. The training was done for 10 min on the weekdays of the last 3 weeks of the study. Analysis of the data indicates that the group training via the stepwise or phasic paradigm showed greater increases in both the positive and negative vergences. Both groups achieved substantial increases in both the negative and positive vergences. The significance of these results is discussed.

Classification criterion for success in the treatment of convergence insufficiency.

Using data collected from a retrospective study of the records of 110 patients diagnosed as having convergence insufficiency, a model has been developed which allows the classification of a patient into one of two categories of success (total or partial/none) on the basis of an initial examination. The subjects were treated with orthoptics and classified into either the total success group (no objective or subjective visual difficulties) or the partial/no success group. Stepwise discriminant analysis was used in the data reduction phase in which 6 of 14 possible variables were selected which best explained the variation in the degree of success. These six variables were: (1) the AC/A ratio; (2) the negative vergence blur value at 40 cm; (3) the recovery value of the positive vergences at 6 m; (4) the break value of the positive vergence at 6 m; (5) the amplitude of accommodation; and (6) the frequency of the deviation. Subjects were more likely to be successful when 1, 2 and 3 were high, 4 and 5 were low, and the deviation was latent. Discriminant analysis using these six variables allowed 25 of 33 (76%) of the patients to be correctly classified in terms of their success. The application of the model for classifying patients with convergence insufficiency is presented and briefly discussed.

Convergence insufficiency.

A retrospective study of 110 subjects with convergence insufficiency has been completed. Their mean age was 19.9 years. There were 72 females and 38 males in the group. The clinical profiles of these subjects were examined before and after a standard orthoptic treatment regimen. Over the course of treatment, the near angle of deviation, the AC/A ratio, a portion of the negative vergence values, all the positive vergence values, the nearpoint of convergence, and the amplitude of accommodation were found to have changed in a statistically significant manner. The importance of these findings is discussed.