Local Structural Variability Research Articles

Temperature-induced structure evolution in CoxBy liquids studied by ab initio molecular dynamics simulation

The relationship between the local structures and the thermodynamic properties of metallic liquids has been a fundamental issue, which significantly impacts the comprehensive performances of metallic materials. The temperature-induced structure evolution in CoxBy alloy liquids, involving CoB, Co2B, Co3B, and Co23B6, was investigated using ab initio molecular dynamics simulations. The results show that the clusters of icosahedral-like polyhedrons are found predominantly in all alloys at low temperature, while the heating induces the decrease in ideal icosahedral and the increase in defected icosahedral. At high temperature, the polyhedron clusters decrease significantly and the ideal icosahedra transforms into smaller short-range polyhedrons, signifying the temperature-induced chemical structure change from long-range to short-range ordering. The aggregation of B atoms at high temperature is confirmed by atomic configuration, charge density, and B-centered Voronoi polyhedrons, and the α-Co single phase is observed below 1600 K. This study is helpful for understanding the local structure variability in eutectic Co-B alloys and guiding solidification path in theory.

일본의 COC+정책에서 지역지향교육이 지역애착과 지역정착에 미치는 효과

Purpose: The purpose of this paper is to find the educational effects of ‘the community-oriented education’ using the data of follow-up surveys of local university students. Japan’s MEXT had promoted the community-oriented education through twice COC and COC+ projects by mobilizing all local resources. It was consistent with the direction of educational reform at local universities. Korean society can obtained some important implications from this research results for the local youth settlement policy.
 Research design, data, and methodology: The existing studies on local settlement were used to cross-section data, so dynamic changes could not be confirmed. This study can confirm the attitude changes in the local attachment and the local-employment settlement between those who received and did not receive the community-oriented education by using data from two times: May of freshmen, November of third grade. This study used DD analysis.
 Results: According to this study, the educational effect only appeared to be limited to the students coming from other regions rather than those within the region. Rather, we find out that local experiences such as volunteer activities and club activities increase the attachment to the local community. According to the estimation results on local-employment of local youth, local industrial structure and job opportunities variables were more significant. The local employment opportunities were a direct factor in local employment decisions of local university students.
 Implications: The community-oriented education is not only a classroom-based local studies, but also a new approach to opportunities to contact the local community, such as volunteer activities in the region. The conclusions that regional experiences such as solving local problems, internship activities at local companies and local volunteer working increase local attachment are also meaningful in Korea’s regional policy. At the same time, it can be said that community-oriented education has a greater effective meaning in the elementary and secondary school curriculum than in universities.

Regioselectivity of the Thunbergia alata Δ6-16:0-acyl carrier protein desaturase by molecular dynamics.

The plant acyl-acyl carrier protein (ACP) desaturases are a family of soluble enzymes that convert saturated fatty-acyl ACPs into their cis-monounsaturated equivalents in an oxygen-dependent reaction. These enzymes play a key role in biosynthesis of mono-unsaturated fatty acids in plants. The archetype of this group is the Δ9-18:0-ACP desaturase that introduces a cis double bond between carbons 9 and 10 to produce oleoyl-ACP. Several variants expressing distinct regioselectivity have been described including a Δ6-16:0-ACP desaturase from black-eyed Susan vine (Thunbergia alata). ACPs are central proteins in the fatty acid biosynthesis that deliver the substrate to the desaturase. They have been reported to show a varying degree of local dynamics and structural variability depending on the substrate length. It has been suggested that the substrate specific change in structure and dynamics is crucial for the decreasing enzymatic activity in the case of the Δ9-Desaturase for chains length shorter than 18. Using molecular dynamics (MD) simulations, we identified a low-energy complex between 16:0-ACP and the desaturase that would position carbons 6 and 7 of the acyl chain adjacent to the diiron active site. The model complex was used to identify mutant variants that could convert the T. alata Δ6 desaturase to Δ9 regioselectivity. Additional modeling between ACP and the mutant variants confirmed the predicted regioselectivity. The computational workflow for revealing the mechanistic understanding of regioselectivity presented herein lays a foundation for designing acyl-ACP desaturases with novel selectivities to increase the diversity of monoenes available for bioproduct applications.

Subsalt Rotliegend Sediments—A New Challenge for Geothermal Systems in Poland

New seismic data and the completion of the K-1 petroleum exploratory well, located close to the axial zone of the Mogilno-Łódź Trough (Polish Lowlands) delivered new insight into local structural, tectonic, facial and thermal variability of this geological unit. In this paper, the two variants of 3D models (SMV1 and SMV2) of Permian-Mesozoic strata are presented for the salt pillow related Kłecko Anticline, while resources assessment was confined to the Rotliegend Enhanced Geothermal System (EGS) type reservoir, that is divided into Playa, Eolian and Fluvial facies-based complexes. Using very conservative assumptions on the methods of the EGS reservoir development, authors assessed that heat in place and technical potential for eolian sandstones are about 386 PJ and ca. 2814 kW, respectively, and for Fluvial 367 PJ and ca. 2850 kW in relation to the volume of 1 km3 at depths of about 5000 m b.s.l. The authors recommend for the further development of the Eolian complex because of its low shale content, influencing the high susceptibility to fracking. The presented research is the first Polish local resources assessment for an EGS reservoir in sedimentary Rotliegend, within thermal anomaly below the salt pillow, which is one of over 100 salt structures mapped in Poland.

The co-occurrence of Ural Owls Strix uralensis and Northern Goshawks Accipiter gentilis differs between extensive and fragmented forests

ABSTRACT Capsule Territories of the nocturnal Ural Owl Strix uralensis and diurnal Northern Goshawk Accipiter gentilis were spatially associated in fragmented forest but not in extensive forest. Aims To test the hypotheses that (i) the patterns of distribution of Ural Owl and Northern Goshawk territories are different in extensive and fragmented forests and (ii) the distribution of their territories do not depend on local forest structure and habitat variables. Methods The territories of Northern Goshawks and Ural Owls were identified in forests in southern Poland. Spatial analysis was used to examine the co-occurrence patterns of the two species, and multivariate analysis to examine the impact of environmental cues on territory selection. Results Most habitat parameters were not significantly related to the presence of territories of either species. For Northern Goshawk there was a positive association with the occurrence of old-growth patches and a negative association with clear-cut areas and proximity to forest edge in fragmented forests; for Ural Owl there was a significant effect of wood type in extensive forest. None of the habitat parameters distinguished the territories of the two species, suggesting similarity in the habitats used. The territories of the two species were spatially associated in fragmented forests, suggesting some positive interspecific relationship. In contrast, the distributions of the two species were not significantly associated in extensive forest. Conclusions To explain the spatial co-occurrence between Northern Goshawks and Ural Owls we suggest: (i) Ural Owls can occupy unused Northern Goshawk nests in managed extensive forest where there is a deficiency of large tree cavities; (ii) restricted availability of habitat in fragmented forests forces both species to nest in close proximity, and/or (iii) Ural Owls use social information from Northern Goshawks about habitat quality when selecting territories in some landscapes.

Seed rain in cocoa agroforests is induced by effects of forest loss on frugivorous birds and management intensity

Tropical forests have been intensively degraded and deforested for different anthropogenic uses, mostly associated to agricultural expansion due to increasing human demands. Therefore, an emerging number of studies has advocated on the benefits of land-sharing strategies such as agroforestry systems which conciliate biodiversity conservation with production. Yet features at both landscape and local scales could affect ecological processes and productivity within agroforests. Here, we used structural equation models to investigate the direct and indirect effects of landscape forest cover, animal seed dispersers and local vegetation variables on the seed rain structure of cocoa (Theobroma cacao) agroforests of the Brazilian Atlantic forest. We sampled seed rain for 12 consecutive months, performed bird and bat surveys and measured local structure variables related to management intensification (i.e., lower abundance and richness of adult trees and lower canopy shading indicating farm intensification) in 15 farms embedded within landscapes showing varying forest cover amount (2.3–74.9 %). Our results indicate that total and animal-dispersed seed richness in cocoa agroforests increased in more forested landscapes induced by the frugivorous bird richness, whereas the abundance of total and animal-dispersed seeds was greater in more shaded farms. Contrary to expectations, the abundance of total and animal-dispersed trees negatively influenced the richness of frugivorous birds, thus indirectly affecting the richness of total and animal-dispersed seeds. Finally, we observed a weak similarity among the composition of arrived seeds and adult trees of animal-dispersed species recorded in the same sampling sites, suggesting that several seeds were actively dispersed from other localities. Our results therefore demonstrate that landscape forest amount and local management intensification play key roles in determining the seed diversity reaching cocoa agroforestry farms. We emphasize the importance of retaining native vegetation cover around the cocoa agroforestry, by either preserving the existing forest remnants or promoting restoration programs within deforested landscapes, in addition to locally ensure tree shading to boost seed arrival and enhance ecosystem functionality.

Atomistic insight on structure and dynamics of spinach acyl carrier protein with substrate length

The plant acyl-acyl carrier protein (ACP) desaturases are a family of soluble enzymes that convert saturated fatty acyl-ACPs into their cis-monounsaturated equivalents in an oxygen-dependent reaction. These enzymes play a key role in biosynthesis of monounsaturated fatty acids in plants. ACPs are central proteins in fatty acid biosynthesis that deliver acyl chains to desaturases. They have been reported to show a varying degree of local dynamics and structural variability depending on the acyl chain size. It has been suggested that substrate-specific changes in ACP structure and dynamics have a crucial impact on the desaturase enzymatic activity. Using molecular dynamics simulations, we investigated the intrinsic solution structure and dynamics of ACP from spinach with four different acyl chains: capric (C10), myristic (C14), palmitic (C16), and stearic (C18) acids. We found that the fatty acids can adopt two distinct structural binding motifs, which feature different binding free energies and influence the ACP dynamics in a different manner. Docking simulations of ACP to castor Δ9-desaturase and ivy Δ4-desaturase suggest that ACP desaturase interactions could lead to a preferential selection between the motifs.

The influence of structural variations on the constitutive response and strain variations in thin fibrous materials

The stochastic variations in the structural properties of thin fiber networks govern to a great extent their mechanical performance. To assess the influence of local structural variability on the local strain and mechanical response of the network, we propose a multiscale approach combining modeling, numerical simulation and experimental measurements. Based on micro-mechanical fiber network simulations, a continuum model describing the response at the mesoscale level is first developed. Experimentally measured spatial fields of thickness, density, fiber orientation and anisotropy are thereafter used as input to a macroscale finite-element model. The latter is used to simulate the impact of spatial variability of each of the studied structural properties. In addition, this work brings novelty by including the influence of the drying condition during the production process on the fiber properties. The proposed approach is experimentally validated by comparison to measured strain fields and uniaxial responses. The results suggest that the spatial variability in density presents the highest impact on the local strain field followed by thickness and fiber orientation. Meanwhile, for the mechanical response, the fiber orientation angle with respect to the drying restraints is the key influencer and its contribution to the anisotropy of the mechanical properties is greater than the contribution of the fiber anisotropy developed during the fiber sheet-making.

Local Population Structure and Seasonal Variability of Borrelia garinii Genotypes in Ixodes ricinus Ticks, Slovakia.

Lyme disease (LD) is the most common tick-borne human disease in Europe, and Borrelia garinii, which is associated with avian reservoirs, is one of the most genetically diverse and widespread human pathogenic genospecies from the B. burgdorferi sensu lato (s.l.) complex. The clinical manifestations of LD are known to vary between regions and depend on the genetic strain even within Borrelia genospecies. It is thus of importance to explore the genetic diversity of such pathogenic borreliae for the wide range of host and ecological contexts. In this study, multilocus sequence typing (MLST) was employed to investigate the local population structure of B. garinii in Ixodes ricinus ticks. The study took place in a natural wetland in Slovakia, temporally encompassing spring and autumn bird migration periods as well as the breeding period of resident birds. In total, we examined 369 and 255 ticks collected from 78 birds and local vegetation, respectively. B. burgdorferi s.l. was detected in 43.4% (160/369) of ticks recovered from birds and in 26.3% (67/255) of questing ticks, respectively. Considering the ticks from bird hosts, the highest prevalence was found for single infections with B. garinii (22.5%). Infection intensity of B. garinii in bird-feeding ticks was significantly higher than that in questing ticks. We identified ten B. garinii sequence types (STs) occurring exclusively in bird-feeding ticks, two STs occurring exclusively in questing ticks, and one ST (ST 244) occurring in both ticks from birds and questing ticks. Four B. garinii STs were detected for the first time herein. With the exception of ST 93, we detected different STs in spring and summer for bird-feeding ticks. Our results are consistent with previous studies of the low geographic structuring of B. garinii genotypes. However, our study reveals some consistency in local ST occurrence and a geographic signal for one of the clonal complexes.

Detection of single DNA mismatches by force spectroscopy in short DNA hairpins.

Identification of defective DNA structures is a difficult task, since small differences in base-pair bonding are hidden in the local structural variability of a generally random base-pair sequence. Defects, such as base mismatches, missing bases, crosslinks, and so on, occur in DNA with high frequency and must be efficiently identified and repaired to avoid dire consequences such as genetic mutations. Here, we focus on the detection of base mismatches, which is local deviations from the ideal Watson-Crick pairing rule, which may typically originate from DNA replication process, foreign chemical attack, or ionizing radiation. Experimental detection of a mismatch defect demands the ability to measure slight deviations in the free energy and molecular structure. We introduce different mismatches in short DNA hairpins (10 or 20 base pairs plus a 4-base loop) sandwiched between dsDNA handles to be used in single-molecule force spectroscopy with optical tweezers. We perform both hopping and force-pulling experiments to measure the excess free energies and deduce the characteristic kinetic signatures of the mismatch from the force-distance curves. All-atom molecular dynamics simulations lend support to the detailed interpretation of the experimental data. Such measurements, at the lowest sensitivity limits of this experimental technique, demonstrate the capability of identifying the presence of mismatches in a random complementary dsDNA sequence and provide lower bounds for the ability to distinguish different structural defects.

Resolving Free-Energy Contributions of Substrate Delivery to Desaturase by Atomistic Simulations

The plant acyl-acyl carrier protein (ACP) desaturases are a family of soluble enzymes that convert saturated fatty-acyl ACPs into their cis-monounsaturated equivalents in an oxygen-dependent reaction. These enzymes play a key role in biosynthesis of mono-unsaturated fatty acids in plants. The archetype of this group is the ▵9-18:0-ACP desaturase that introduces a cis double bond between carbons 9 and 10 to produce oleoyl-ACP. ACPs are central proteins in the fatty acid biosynthesis that deliver the substrate to the desaturase. They have been reported to show a varying degree of local dynamics and structural variability depending on the substrate length. It has been suggested that the substrate specific change in structure and dynamics is crucial for the decreasing enzymatic activity in the case of the ▵9-desaturase for chains length shorter than 18. We investigated the solution structure and dynamics of ACP with four different substrate lengths (10, 14, 16, and 18) based on published NMR solution structures using extensive all atom molecular dynamics simulations. Umbrella sampling and replica exchange dynamics simulations highlight the chain length depend free energy of substrate binding and chain length depended binding motifs. This suggests that longer substrates have a lower binding energy, but also a much larger ensemble of structures that are accessible. Thereby estimating the effect on changes in the binding affinity of the substrate bound Acyl carrier protein to the ▵9-desaturase will not be able without taking into account the Enzyme itself.

Regulation of the functional structure of aquatic communities across spatial scales in a major river network.

Moving beyond species count data is an essential step to better understand the effects of environmental perturbations on biodiversity and ecosystem functions, and to eventually better predict the strength and direction of those effects. Here, coupling an integrative path analysis approach with data from an extensive countrywide monitoring program, we tested the main spatial, environmental and anthropogenic drivers of change in the functional structure of aquatic macroinvertebrate communities along the entire Swiss Rhine river catchment. Functional structure was largely driven by inherent altitudinal variation influencing and cascading to regional scaled factors such as land use change and position in the riverine network, which, in turn, transformed local habitat structure variables. Those cascading effects across scales propagated through the biotic community, first affecting prey and, in turn, predators. Our results illustrate how seemingly less important local factors can act as essential transmission belts, propagating through direct and indirect pathways across scales to generate the specific context in which each functional group will strive or not, leading to characteristic landscape wide variations in functional community structure.

The effect of structural variability and local site conditions on building fragility functions

In this study, the effect of local site conditions (site class and site amplifications) and structural variability are investigated on fragility functions of typical building structures. The study area is chosen as Eastern Turkey. The fragility functions are developed using site-specific uniform hazard spectrum (UHS). The site-specific UHS is obtained based on simulated ground motions. The implementation of ground motion simulation into seismic hazard assessment has the advantage of investigating detailed local site effects. The typical residential buildings in Erzincan are represented by equivalent single degree of freedom systems (ESDOFs). Predictive equations are accomplished for structural seismic demands of ESDOFs to derive fragility functions in a straightforward manner. To study the sensitivity of fragility curves to site class, two sites on soft and stiff soil are taken into account. Two alternative site amplification functions known as generic and theoretical site amplifications are examined for these two sites. The reinforced concrete frames located on soft soil display larger fragilities than those on stiff soil. Theoretical site amplification mostly leads to larger fragilities than generic site amplification more evidently for reinforced concrete buildings. Additionally, structural variability of ESDOFs is generally observed to increase the fragility especially for rigid structural models.

The direct and indirect effects of economic wealth on time to take-off

Our objective is to decompose the influence of the economic wealth on the time to sales take-off into a direct effect and an indirect effect through time to introduction. We use a traditional regression based and an advanced counterfactual framework for our analysis, based on adoption data for four generations of mobile phone from 172 countries. Our study extends the sales take-off literature by better understanding how the commercialization stage (time to introduction) affects the confirmation stage (time to sales take-off) in innovation diffusion while controlling for local market structure, socio-economic, demographic and cultural variables suggested in the literature. We show that economic wealth exerts: a positive direct effect by shortening sales take-off time; a negative indirect effect by shortening time to introduction which tends to extend time to sales take-off. The uncovering of this relationship is achieved by treating time to introduction as a mediating variable, departing from previous studies where it is treated as an exogeneous variable. We further show that the negative indirect effect is diluted in the case of high income countries but not in the case of upper middle-income countries. A sensitivity analysis shows the robustness of our findings. Our findings will help firms develop optimal market entry strategies considering the resources available.

Exploring the potential of a structural alphabet-based tool for mining multiple target conformations and target flexibility insight.

Protein flexibility is often implied in binding with different partners and is essential for protein function. The growing number of macromolecular structures in the Protein Data Bank entries and their redundancy has become a major source of structural knowledge of the protein universe. The analysis of structural variability through available redundant structures of a target, called multiple target conformations (MTC), obtained using experimental or modeling methods and under different biological conditions or different sources is one way to explore protein flexibility. This analysis is essential to improve the understanding of various mechanisms associated with protein target function and flexibility. In this study, we explored structural variability of three biological targets by analyzing different MTC sets associated with these targets. To facilitate the study of these MTC sets, we have developed an efficient tool, SA-conf, dedicated to capturing and linking the amino acid and local structure variability and analyzing the target structural variability space. The advantage of SA-conf is that it could be applied to divers sets composed of MTCs available in the PDB obtained using NMR and crystallography or homology models. This tool could also be applied to analyze MTC sets obtained by dynamics approaches. Our results showed that SA-conf tool is effective to quantify the structural variability of a MTC set and to localize the structural variable positions and regions of the target. By selecting adapted MTC subsets and comparing their variability detected by SA-conf, we highlighted different sources of target flexibility such as induced by binding partner, by mutation and intrinsic flexibility. Our results support the interest to mine available structures associated with a target using to offer valuable insight into target flexibility and interaction mechanisms. The SA-conf executable script, with a set of pre-compiled binaries are available at http://www.mti.univ-paris-diderot.fr/recherche/plateformes/logiciels.

Oxygen Vacancy Formation, Mobility, and Hydrogen Pick-up during Oxidation of Zirconium by Water

A comprehensive first principles understanding of the oxidation of zirconium alloys by water was reiterated. Two channels were taken to jointly constitute to the oxidation process: one according to classical oxidation theory involving hydrogen evolution and the second reflected by inwards transport of protons causing hydrogen pick-up. The two were associated with charged and uncharged oxygen vacancies, respectively. The purpose of the present study was to clarify the nature of the effective anode during oxidation of zirconium as to the detailed role of the metal. Oxygen dissolution in the alloy resulted in a “pre-anodic” property associated with the formation of oxygen vacancy VO in the oxide, i.e., preceding VO2+/2e− separation. Atomistic perspective on the metal/oxide interface before nucleation of VO was provided. The rapid convergence of the model interface to bulk properties in spite of the local structural variability provided new insight as to the nature of an amorphous metal/oxide interface.

Exploring the spatial heterogeneity of entrepreneurship in Chinese manufacturing industries

The prevalence of entrepreneurship not only varies across regions, but also differs among industries. Based on a unique data set of 146 manufacturing industries across 30 provincial-level regions in China, this study investigates the importance of geographical conditions and industry dynamism on net entry rates of Chinese manufacturing firms, and empirically explores how these two sets of factors jointly influence the distributional pattern of entrepreneurship. By testing for the significance of interactions between industry dynamism and local condition variables, it is found that growth-driven entrepreneurial activities favor agglomerated regions and do not value knowledge creation capability much, although both knowledge creation capability and factor market maturity are important for a region to attract entrepreneurs pursuing technological opportunities. For start-ups exploiting niche opportunities, agglomeration and local competition both act as deterring factors. Overall, the results confirm the importance of local conditions and industry structural variables as joint determinants of entrepreneurship in Chinese manufacturing industries.

Predicting wood fiber attributes using local-scale metrics from terrestrial LiDAR data: A case study of Newfoundland conifer species

Knowledge of wood fiber attributes (WFA) is important for evaluating forest resources and optimizing efficiency in the forest industry. To improve our ability to estimate WFA in the forest, we analyzed the relationships between structural metrics derived from terrestrial laser scanner (TLS) data and four key attributes of industrial significance: wood density, fiber length, microfibril angle, and coarseness. We developed a suite of structural metrics that relate to four aspects of the forest: canopy structure, competition, vegetation density, and local topography. We modeled WFA for sites dominated by black spruce (Picea mariana) and balsam fir (Abies balsamea) trees. For black spruce sites, R2 values ranged from 63% to 72%. Structural metrics that relate to competition were the strongest explanatory variables. For balsam fir sites, R2 ranged from 37% to 63% using structural metrics that relate mostly to canopy structure. Our results demonstrate that local structural variables are useful explanatory variables for predicting WFA of the dominant coniferous species in Newfoundland.

Quantitative assessment of multiscale structural and functional alterations in asthmatic populations.

Relationships between structural and functional variables in asthmatic lungs at local and global (or lobar) levels remain to be discovered. This study aims to investigate local alterations of structural variables [bifurcation angle, circularity, airway wall thickness (WT), and hydraulic diameter (Dh)] in asthmatic subjects, and their correlations with other imaging and pulmonary function test-based global and lobar metrics, including lung shape, air-trapping, regional volume change, and more. Sixty-one healthy subjects, and 67 nonsevere and 67 severe asthmatic subjects were studied. The structural variables were derived from computed tomography images at total lung capacity (TLC). Air-trapping was measured at functional residual capacity, and regional volume change (derived from image registration) was measured between functional residual capacity and TLC. The tracheal diameter and WT predicted by 61 healthy subjects were used to normalize the Dh and WT. New normalization schemes allowed for the dissociation of luminal narrowing and wall thickening effects. In severe asthmatic subjects, the alteration of bifurcation angle was found to be correlated with a global lung shape at TLC, and circularity was significantly decreased in the right main bronchus. While normalized WT increased especially in the upper lobes of severe asthmatic subjects, normalized Dh decreased in the lower lobes. Among local structural variables, normalized Dh was the most representative variable, because it was significantly correlated with alterations of functional variables, including pulmonary function test's data. In conclusion, understanding multiscale phenomena may help to provide guidance in the search for potential imaging-based phenotypes for the development and outcomes assessment of therapeutic intervention.

Factors affecting sick leave prescribing in occupational health care: a survey based on hypothetical patient cases.

BackgroundSeveral studies have shown considerable differences in the way that physicians prescribe sick leave. The aim of this study was to examine the sick leave prescribing practices of occupational health care physicians and factors affecting these practices.MethodsA questionnaire study with 19 hypothetical patient cases was conducted among 356 Finnish occupational health care physicians. The effects of both physician-related and local structural background variables on sick leave prescribing were studied using regression models. Economic consequences of the variation in sick leave prescribing were estimated.ResultsWhen the cases were considered individually, the variation in prescribed sick leave days was relatively small. However, when considered together, variation in prescribing practice became apparent. On average, the overall number of days of sick leave prescribed for the entire group of 19 patient cases was 85.8, varying between 21 and 170 days. The physicians working at a public health center and those with more than 20 years experience as an occupational health physician tended to prescribe more days of sick leave than others. The quartile of physicians who prescribed the fewest days of sick leave would have resulted in mean production losses (17,100 euro, 95% CI 16,400-17,700) that were half those in the quartile with the most days of sick leave (34,800 euro, 95% CI 33,600-35,900).ConclusionsThere was variation in the sick leave prescribing practices of occupational health care physicians. The most significant factor affecting this variation was the health care sector (public, private or employer clinic) employing the physicians. Variation in sick leave prescribing patterns can lead to inequality between patients.