The Influence of Internal Time,Time Awake,and Sleep Duration on Cognitive Performance in Shiftworkers

To date, studies investigating the consequences of shiftwork have predominantly focused on external (local) time. Here, we report the daily variation in cognitive performance in rotating shiftworkers under real-life conditions using the psychomotor vigilance test (PVT) and show that this function depends both on external and internal (biological) time. In addition to this high sensitivity of PVT performance to time-of-day, it has also been extensively applied in sleep deprivation protocols. We, therefore, also investigated the impact of shift-specific sleep duration and time awake on performance. In two separate field studies, 44 young workers (17 females, 27 males; age range 20–36 yrs) performed a PVT test every 2?h during each shift. We assessed chronotype by the MCTQ^Shift (Munich ChronoType Questionnaire for shiftworkers). Daily sleep logs over the 4-wk study period allowed for the extraction of shift-specific sleep duration and time awake in a given shift, as well as average sleep duration (“sleep need”). Median reaction times (RTs) significantly varied across shifts, depending on both Local Time and Internal Time. Variability of reaction times around the 24 h mean (≈ ±5%) was best explained by a regression model comprising both factors, Local Time and Internal Time (p < .001). Short (15th percentile; RT_15%) and long (85th percentile; RT_85%) reaction times were differentially affected by Internal Time and Local Time. During night shifts, only median RT and RT_85% were impaired by the duration of time workers had been awake (p?<?.01, consistent with the highest sleep pressure), but not RT_15%. Proportion of sleep before a test day (relative to sleep need) significantly affected median RT and RT_85% during morning shifts (p?<?.01). RT_15% was worst in the beginning of the morning shift, but improved to levels above average with increasing time awake (p < .05), whereas RT_85% became worse (p < .05). Hierarchical mixed models confirmed the importance of chronotype and sleep duration on cognitive performance in shiftworkers, whereas the effect of time awake requires further research. Our finding that both Local Time and Internal Time, in conjunction with shift-specific sleep behavior, strongly influence performance extends predictions derived from laboratory studies. (Author correspondence: roenneberg@lmu.de)     

Time budget and activity patterns of the lion-tailed macaque (Macaca silenus)

We studied time budgeting of lion-tailed macaques in the Anamalai Wildlife Sanctuary, Tamil Nadu, India, with regard to seven activity categories. Groups spent >50% of their time feeding and foraging, 33% of the time resting, and 15% moving. More energetic activities were spread uniformly through the day. Feeding had two annual peaks: one closely following the northeast monsoon and the other corresponding to the southwest monsoon. These also coincided with peaks of food availability and mating. Time saved in feeding was spent mostly on resting. Ranging showed a pattern contrary to that of time spent moving and was related more to weather than to food availability; it increased during cooler periods. The middle and upper stories of the canopy were used >93% of the time. The ground was used rarely. Time budgeting characteristics of the lion-tailed macaque are primarily frugiinsectivorous adaptations to a wet evergreen forest habitat.     

The Meaning of Time

Abstract

Jeremy Rifkin. Time Wars. New York: Touchstone Books, Simon & Schuster, 1989. 302 pp. $9.95 paperback.     

Assessment of HER-2 gene overexpression in Isfahan province breast cancer patients using Real Time RT-PCR and immunohistochemistry

Purpose

Overexpression of proto-oncogene HER-2 is one of the main molecular markers of breast cancer involved in prognosis and diagnosis and also in trastuzumab therapy. Thus, a request for the evaluation of HER-2 status in breast cancer has been increasing. The aim of our study was assessment of HER-2 overexpression in malignant and benign breast cancer specimens by Real Time RT-PCR technique and comparison of its results with IHC outcomes.

Methods

Twenty benign and sixty malignant breast cancers in addition to fifteen normal breast tissue specimens were analyzed by Real Time RT-PCR method. Fresh tissue samples were disrupted by mortar and pestle. A syringe and a needle were used for complete homogenization of the tissues. The RNA was then isolated from the samples and converted to cDNA. A standard curve was initially plotted using BioEasy SYBR Green I and then all 95 specimens were studied by Real Time RT-PCR using 2^− ΔΔCt method.

Results

23.3% of 60 malignant specimens showed HER-2 overexpression, while all of the benign samples represented the normal expression level of HER-2 gene. The concordance rate between the results of Real Time RT-PCR and IHC was 86.6%.

Conclusion

Real Time RT-PCR method is an almost reliable technique and at least can be used as a complementary method for confirming IHC results. This is emanated from relatively high rate of concordance between outcomes of IHC test, as a routine method of detecting the HER-2 gene expression status, and Real Time RT-PCR technique.     

Stitches on Time: Colonial Textures and Postcolonial Tangles

Stitches on Time: Colonial Textures and Postcolonial Tangles . Saurabh Dube. Durham, NC: Duke University Press, 2004. 259 pp.     

From Time Immemorial: Indigenous Peoples and State Systems

From Time Immemorial: Indigenous Peoples and State Systems. Richard J. Perry. Austin: University of Texas Press, 1996. 302 pp.     

Dress and Ethnicity: Change across Time and Space

Dress and Ethnicity: Change across Time and Space. Joanne B. Eicher. ed. Oxford, England: Berg Publishers Limited, 1995.316 pp.     

Time, a quality-control parameter in flow cytometry

Time has been used as a quality-control parameter in our flow cytometer. This parameter was automatically incorporated into the list-mode data base by hooking the computer clock directly into the acquisition logic. Quality control can then be checked by "replaying" fluorescence or light scatter data vs. time and any instrumental drift can be observed and degraded data can be excised. The technique is illustrated with a number of DNA data sets from a tissue culture cell line in which artificial perturbations were introduced during data acquisition to simulate potential causes of instrumental drift.     

Time, Process and Structured Transformation in Archaeology

Time, Process and Structured Transformation in Archaeology. Sander E. van der Leeuw and James McGlade. eds. New York: Routledge, 1997.484pp.     

Current Studies in Archaeoastronomy: Conversations across Time and Space

Current Studies in Archaeoastronomy: Conversations across Time and Space. John W. Fountain and Rolf M. Sinclair, eds. Durham, NC: Carolina Academic Press, 2005. 579 pp.     

Prothrombin Time and Activated Partial Thromboplastin Time Testing: A Comparative Effectiveness Study in a Million-Patient Sample

Background

A substantial fraction of all American healthcare expenditures are potentially wasted, and practices that are not evidence-based could contribute to such waste. We sought to characterize whether Prothrombin Time (PT) and activated Partial Thromboplastin Time (aPTT) tests of preoperative patients are used in a way unsupported by evidence and potentially wasteful.

Methods and Findings

We evaluated prospectively-collected patient data from 19 major teaching hospitals and 8 hospital-affiliated surgical centers in 7 states (Delaware, Florida, Maryland, Massachusetts, New Jersey, New York, Pennsylvania) and the District of Columbia. A total of 1,053,472 consecutive patients represented every patient admitted for elective surgery from 2009 to 2012 at all 27 settings. A subset of 682,049 patients (64.7%) had one or both tests done and history and physical (H&P) records available for analysis. Unnecessary tests for bleeding risk were defined as: PT tests done on patients with no history of abnormal bleeding, warfarin therapy, vitamin K-dependent clotting factor deficiency, or liver disease; or aPTT tests done on patients with no history of heparin treatment, hemophilia, lupus anticoagulant antibodies, or von Willebrand disease. We assessed the proportion of patients who received PT or aPTT tests who lacked evidence-based reasons for testing.

Conclusions

This study sought to bring the availability of big data together with applied comparative effectiveness research. Among preoperative patients, 26.2% received PT tests, and 94.3% of tests were unnecessary, given the absence of findings on H&P. Similarly, 23.3% of preoperative patients received aPTT tests, of which 99.9% were unnecessary. Among patients with no H&P findings suggestive of bleeding risk, 6.6% of PT tests and 7.1% of aPTT tests were either a false positive or a true positive (i.e. indicative of a previously-undiagnosed potential bleeding risk). Both PT and aPTT, designed as diagnostic tests, are apparently used as screening tests. Use of unnecessary screening tests raises concerns for the costs of such testing and the consequences of false positive results.     

Introduction to "Landscapes over Time"

There is a growing recognition that modern environmental problems bear striking resemblance to those faced by past societies and that to understand the environmental present we must consider the total sweep of anthropogenic environmental change on specific landscapes. This "In Focus" assembles five articles encompassing diverse time periods and different global regions to make the case that long-term perspectives on the relationship between people and their environmental contexts are critical for understanding and evaluating contemporary environmental debates, interpretations, and even policies.     

Study of Natural Genetic Variation in Early Fitness Traits Reveals Decoupling Between Larval and Pupal Developmental Time in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

Characterizing the relationships between genotype and phenotype for developmental adaptive traits is essential to understand the evolutionary dynamics underlying biodiversity. In holometabolous insects, the time to reach the reproductive stage and pupation site preference are two such traits. Here we characterize aspects of the genetic architecture for Developmental Time (decomposed in Larval and Pupal components) and Pupation Height using lines derived from three natural populations of Drosophila melanogaster raised at two temperatures. For all traits, phenotypic differences and variation in plasticity between populations suggest adaptation to the original thermal regimes. However, high variability within populations shows that selection does not exhaust genetic variance for these traits. This could be partly explained by local adaptation, environmental heterogeneity and modifications in the genetic architecture of traits according to environment and ontogenetic stage. Indeed, our results show that the genetic factors affecting Developmental Time and Pupation Height are temperature-specific. Varying relationships between Larval and Pupal Developmental Time between and within populations also suggest stage-specific modifications of genetic architecture for this trait. This flexibility would allow for a somewhat independent evolution of adaptive traits at different environments and life stages, favoring the maintenance of genetic variability and thus sustaining the traits’ evolvabilities.     

20th International Symposium on Shiftwork and Working Time: Biological Mechanisms,Recovery, and Risk Management in the 24-h Society

This dedicated issue of Chronobiology International is devoted to the selected proceedings of the 20th International Symposium on Shift Work and Working Time held in Stockholm, Sweden, 28 June to 1 July 2011. It constitutes the fifth such issue of the journal since 2004 dedicated to the selected proceedings to the meetings of the Working Time Society. The key theme of the 20th Symposium was “Biological Mechanisms, Recovery, and Risk Management in the 24-h Society.” The collection of papers of this dedicated issue represents the best of contemporary research on the effects of night and rotating shift schedules on worker health and safety. The contents cover such topics as sleep restriction, injuries, health, and performance of night work and rotating shiftwork, plus light treatment as a countermeasure against the circadian disruption of shiftwork. The majority of the papers are observational field studies, including some of large sample size, and three studies are well-designed laboratory experiments. (Author correspondence: goran.kecklund@stress.su.se)     

Time and Complexity in Historical Ecology: Studies in the Neotropical Lowlands

Time and Complexity in Historical Ecology: Studies in the Neotropical Lowlands . William Baleé and Clark L. Erickson, eds. New York: Columbia University Press, 2006. 417 pp.     

The Night Is Young: Sexuality in Mexico in the Time of AIDS

The Night Is Young: Sexuality in Mexico in the Time of AIDS. Héctor Carrillo. Chicago: University of Chicago Press, 2002. 352 pp.     

Contingent Lives: Fertility, Time, and Aging in West Africa.

Contingent Lives: Fertility, Time, and Aging in West Africa. Caroline H. Bledsoe. Chicago: University of Chicago Press, 2002. xii. 396 pp.     

A Place against Time: Land and Environment in the Papua New Guinea Highlands

Place against Time: Land and Environment in the Papua New Guinea Highlands. Paul Sillitoe. London: Harwood Academic Publishers, 1996. 438 pp.     

The Construction of Minorities: Cases for Comparison across Time and around the World.

The Construction of Minorities: Cases for Comparison across Time and around the World. Andre Burguiere and Raymond Grew. eds. Ann Arbor: University of Michigan Press, 2001. 345 pp.