A field comparison of neck and shoulder postures in symptomatic and asymptomatic office workers

Poor neck and shoulder postures have been suggested to be a cause of neck and shoulder pain in computer workers. The present study aimed to evaluate and compare the head, neck and shoulder postures of office workers with and without symptoms in these regions, in their actual work environments. The two all female subject groups reported significantly different discomfort scores across five trials repeated in a single working day. The results of repeated video capture and two-dimensional motion analysis showed that there were trends for increased head tilt and neck flexion postures in the symptomatic subjects (n = 8), compared to the asymptomatic subjects (n = 8). Symptomatic subjects also tended to have more protracted acromions compared with asymptomatic subjects and showed greater movement excursions in the head segment and the acromion. All subjects demonstrated an approximately 10% increase in forward head posture from their relaxed sitting postures when working with the computer display, but there were no significant changes in posture as a result of time-at-work.     

A multi-institutional, multinational study of programming concepts using card sort data

Abstract: This paper presents a case study of the use of a repeated single‐criterion card sort with an unusually large, diverse participant group. The study, whose goal was to elicit novice programmers' knowledge of programming concepts, involved over 20 researchers from four continents and 276 participants drawn from 20 different institutions. In this paper we present the design of the study and the unexpected result that there were few discernible systematic differences in the population. The study was one of the activities of the National Science Foundation funded Bootstrapping Research in Computer Science Education project (2003).     

Cross-validation of an abbreviated form of the Halstead Category Test.

Cross-validated the use of a short form of the Halstead Category Test as suggested by D. A. Calsyn et al (see record 1981-02450-001). For 60 Ss (mean age 36.72 yrs), it was found that the total score estimated from their formula (based on the 1st 4 subtests of the Category Test) correlated .88 with the overall score. The formula was cross-validated in 3 samples with all correlations above .83. It was found that the formula could reliably predict who would exceed the cutoff of the entire test, with an overall accuracy across the 4 samples of 184 out of 205. (3 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Survival and recovery of viable but nonculturable Listeria monocytogenes cells in a nutritionally depleted medium

Survival of a desiccated five-strain Listeria monocytogenes mixture during storage in sand at 4 degrees C for 2 months was determined using the acridine orange direct count method with novobiocin and plate counts. Samples of inoculated sand were taken every 2 weeks, incubated at 37 degrees C for 6 h, stained with acridine orange, and then examined with a fluorescence microscope. Elongated viable but nonculturable cells were most frequently observed during weeks 2 and 4. At weeks 6 and 8, most of the cells either remained viable or were dead. In each microscopic field, only one or two viable but nonculturable cells were observed among hundreds of other viable culturable cells, indicating that L. monocytogenes does not generally become viable but nonculturable. Therefore, viable but nonculturable cells are not a concern when plating environmental samples or desiccated L. monocytogenes cells on nonselective media. Tryptic soy agar with 0.6% (wt/vol) yeast extract (TSAYE) and Columbia agar were used as nonselective plate count media. Modified Oxford agar and TSAYE + 5% (wt/vol) sodium chloride were used as the selective plate count media. The effects of aerobic or anaerobic incubation and media supplementation with 0.1% or 1% (wt/vol) sodium pyruvate were tested to optimize recovery of desiccated cells. Nonselective media showed better recovery when TSAYE and Columbia agar contained 0.1% (wt/vol) pyruvate and were incubated aerobically. These two culture methods were equally effective (P > 0.05) for recovering desiccated L. monocytogenes cells.     

Integral Antireflective Surface Production on Optical Glass

Integral antireflective surfaces with extremely high laser-damage thresholds were prepared on optical glasses by controlled corrosion in neutral solution. Properties of such surfaces are discussed and compared with gradient antireflective surfaces produced on phase-separated borositicate glasses.     

Midlatitude cirrus cloud climatology from the Facility for Atmospheric Remote Sensing. IV. Optical displays

In this fourth of a series of papers that describe long-term cloud research at the Facility for Atmospheric Remote Sensing at Salt Lake City, Utah, an approximately 10-year record of polarization lidar and photographic observations is analyzed to characterize the occurrence of optical displays in our local varieties of midlatitude cirrus clouds. The frequencies of occurrence of various types of halo, arc, and corona displays are evaluated according to their appearance and longevity over nominal 1-h observation periods and to the meteorological source of the cirrus. We find that complex halo-arc displays are rare at our locale and that even the so-called common 22 degree halo occurs infrequently as a complete long-lived ring. For example, only approximately 6% of the 1561-h daytime cirrus periods have bright and prolonged 22 degree halos, although a total of 37.3% have some indications of this halo, even if they are brief and fragmentary. Other fairly frequent features are the 22 degree upper tangent arc (8.6%), 22 degree parhelia (8.5%), and solar corona (7.2%). Of the optical displays observed, 83.6% are refraction based, only 1.9% are due to reflection phenomena, and a surprising 15.4% are caused by diffraction. Complex halo-arc displays are disproportionally associated with cirrus formed in tropical or subtropical airflow and also contain more horizontally oriented planar ice crystals. Lidar linear depolarization ratios from a subset of vivid displays show significant differences between halo- and the corona-producing cirrus, reflecting the effects of particle shape. Halos are associated with relatively warm cirrus that contain randomly and horizontally oriented planar ice crystals, whereas the colder corona cirrus produce much stronger depolarization from crystals too small to be uniformly oriented. Comparisons are made with available information from other locales, and we attempt to explain the geographical differences in terms of basic cirrus cloud processes.     

Multiple-Instance Learning of Real-Valued Geometric Patterns

Recently there has been significant research in multiple-instance learning, yet most of this work has only considered this model when there are Boolean labels. However, in many of the application areas for which the multiple-instance model fits, real-valued labels are more appropriate than Boolean labels. We define and study a real-valued multiple-instance model in which each multiple-instance example (bag) is given a real-valued label in [0, 1] that indicates the degree to which the bag satisfies the target concept. To provide additional structure to the learning problem, we associate a real-valued label with each point in the bag. These values are then combined using a real-valued aggregation operator to obtain the label for the bag. We then present on-line agnostic algorithms for learning real-valued multiple-instance geometric concepts defined by axis-aligned boxes in constant-dimensional space and describe several possible applications of these algorithms. We obtain our learning algorithms by reducing the problem to one in which the exponentiated gradient or gradient descent algorithm can be used. We also give a novel application of the virtual weights technique. In typical applications of the virtual weights technique, all of the concepts in a group have the same weight and prediction, allowing a single representative concept from each group to be tracked. However, in our application there are an exponential number of different weights and possible predictions. Hence, boxes in each group have different weights and predictions, making the computation of the contribution of a group significantly more involved. However, we are able to both keep the number of groups polynomial in the number of trials and efficiently compute the overall prediction.