255 research outputs found

    Unexpected hard-object feeding in Western lowland gorillas

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    The cranial morphology of the earliest known hominins in the genus Australopithecus remains unclear. The oldest species in this genus (Australopithecus anamensis, specimens of which have been dated to 4.2–3.9 million years ago) is known primarily from jaws and teeth, whereas younger species (dated to 3.5–2.0 million years ago) are typically represented by multiple skulls. Here we describe a nearly complete hominin cranium from Woranso-Mille (Ethiopia) that we date to 3.8 million years ago. We assign this cranium to A. anamensis on the basis of the taxonomically and phylogenetically informative morphology of the canine, maxilla and temporal bone. This specimen thus provides the first glimpse of the entire craniofacial morphology of the earliest known members of the genus Australopithecus. We further demonstrate that A. anamensis and Australopithecus afarensis differ more than previously recognized and that these two species overlapped for at least 100,000 years—contradicting the widely accepted hypothesis of anagenesis

    A capability perspective on sustainable employability:A Dutch focus group study on organizational, work and personal conversion factors

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    Objective In the field of work, there is a shift towards more value-based approaches to study the sustainable employability of the present-day worker. The capability approach offers a value based and innovative conceptualisation and framework of sustainable employability characterized by contextuality, normativity and diversity. The capabilities of Dutch employees have been established and validated, yet it is not known which conversion factors on a personal, work and organizational level enable employees to achieve value in work in different Dutch occupational sectors. Methods Our qualitative approach included seven focus groups in different occupational sectors including elderly care, higher education, insurance work, facility management and the oil-, car- and chemical industry. Each focus group included 5–11 participants and took approximately one and a half hour. A qualitative content analysis was used to analyse the data, by combining deductive and inductive coding respectively. Deductive coding involved assigning themes to the conversion of resources into capabilities at the organizational, work and personal level. Results On the organizational conversion level, important themes were cultural aspects, power relations, shortage of personnel and policies for self-management. On the work conversion level, social contacts, communication and workload, tasks and schedules were identified. Social contacts were described as a work value in itself, but also conditional for achieving other work values. On the personal conversion level, experienced work stress, motivation and the ability to achieve values informally within the company. Conclusion From our findings it follows that focus groups are sensitive to identify conversion factors on all three levels of conversion. In addition, companies and their employees might effectively increase work capabilities by being sensitive to all three conversion levels simultaneously. Further research is necessary to study the effect of a capability-based intervention at the work floor

    Sex differences in migraine attack characteristics:A longitudinal E-diary study

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    Objective: In this prospective cohort study, characteristics of perimenstrual and non-perimenstrual migraine attacks in women were compared with migraine attacks in men. Background: Women report longer migraine attacks and more accompanying symptoms than men in cross-sectional questionnaire studies, but this has not been confirmed in longitudinal studies. Supposed differences could result from different characteristics specific to perimenstrual migraine attacks, or of attacks in women in general. Methods: This cohort study was performed among patients with migraine who were treated at the Leiden Headache Clinic. We assessed differences in migraine attack characteristics between men and women who were prospectively followed by a previously validated electronic headache diary. The primary outcome was “attack” duration. Differences between perimenstrual (Days −2 to +3 of the menstrual cycle) and non-perimenstrual attacks in women versus attacks in men were corrected for age, chronic migraine, and medication overuse headache. Results: A total of 1347 women and 284 men were included, reflecting the preponderance of women in migraine prevalence. Crude median (first and third quartile [Q1−Q3]) attack duration in men was 32.1 [17.7–53.6] h, compared to 36.7 [21.9–62.4] h for non-perimenstrual migraine attacks and 44.4 [17.9–79.0] h for perimenstrual migraine attacks in women. After correction for confounding, perimenstrual migraine attacks were 1.62 (95% confidence interval [CI] 1.47–1.79; p &lt; 0.001) and non-perimenstrual 1.15 (95% CI 1.05–1.25; p = 0.003) times longer compared to migraine attacks in men. The mean relapse percentage in men was 9.2%, compared to 12.6% for non-perimenstrual migraine attacks, and 15.7% for perimenstrual migraine attacks. Relapse risk was greater for perimenstrual (odds ratio [OR] 2.39, 95% CI 1.93–2.95; p &lt; 0.001), but not for non-perimenstrual (OR 1.18, 95% CI 0.97–1.45; p = 0.060) attacks. Migraine attacks in women were more often accompanied by photophobia, phonophobia, and nausea, but less often aura. Conclusion: Compared to attacks in men, both perimenstrual and non-perimenstrual migraine attacks are of longer duration and are more often accompanied by associated symptoms. A sex-specific approach to migraine treatment and research is needed.</p

    External Quality Assessment Schemes for Biomarker Testing in Oncology:Comparison of Performance between Formalin-Fixed, Paraffin-Embedded-Tissue and Cell-Free Tumor DNA in Plasma

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    Liquid biopsies have emerged as a useful addition to tissue biopsies in molecular pathology. Literature has shown lower laboratory performances when a new method of variant analysis is introduced. This study evaluated the differences in variant analysis between tissue and plasma samples after the introduction of liquid biopsy in molecular analysis. Data from a pilot external quality assessment scheme for the detection of molecular variants in plasma samples and from external quality assessment schemes for the detection of molecular variants in tissue samples were collected. Laboratory performance and error rates by sample were compared between matrices for variants present in both scheme types. Results showed lower overall performance [65.6% (n = 276) versus 89.2% (n = 1607)] and higher error rates [21.0% to 43.5% (n = 138) versus 8.7% to 16.7% (n = 234 to 689)] for the detection of variants in plasma compared to tissue, respectively. In the plasma samples, performance was decreased for variants with an allele frequency of 1% compared to 5% [56.5% (n = 138) versus 74.6% (n = 138)]. The implementation of liquid biopsy in the detection of circulating tumor DNA in plasma was associated with poor laboratory performance. It is important both to apply optimal detection methods and to extensively validate new methods for testing circulating tumor DNA before treatment decisions are made

    Occurrence of testicular microlithiasis in androgen insensitive hypogonadal mice

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    &lt;b&gt;Background&lt;/b&gt;: Testicular microliths are calcifications found within the seminiferous tubules. In humans, testicular microlithiasis (TM) has an unknown etiology but may be significantly associated with testicular germ cell tumors. Factors inducing microlith development may also, therefore, act as susceptibility factors for malignant testicular conditions. Studies to identify the mechanisms of microlith development have been hampered by the lack of suitable animal models for TM.&lt;BR/&gt; &lt;b&gt;Methods&lt;/b&gt;: This was an observational study of the testicular phenotype of different mouse models. The mouse models were: cryptorchid mice, mice lacking androgen receptors (ARs) on the Sertoli cells (SCARKO), mice with a ubiquitous loss of androgen ARs (ARKO), hypogonadal (hpg) mice which lack circulating gonadotrophins, and hpg mice crossed with SCARKO (hpg.SCARKO) and ARKO (hpg.ARKO) mice.&lt;BR/&gt; &lt;b&gt;Results&lt;/b&gt;: Microscopic TM was seen in 94% of hpg.ARKO mice (n=16) and the mean number of microliths per testis was 81 +/- 54. Occasional small microliths were seen in 36% (n=11) of hpg testes (mean 2 +/- 0.5 per testis) and 30% (n=10) of hpg.SCARKO testes (mean 8 +/- 6 per testis). No microliths were seen in cryptorchid, ARKO or SCARKO mice. There was no significant effect of FSH or androgen on TM in hpg.ARKO mice.&lt;BR/&gt; &lt;b&gt;Conclusions&lt;/b&gt;: We have identified a mouse model of TM and show that lack of endocrine stimulation is a cause of TM. Importantly, this model will provide a means with which to identify the mechanisms of TM development and the underlying changes in protein and gene expression

    Feeding postural behaviors and food geometric and material properties in bearded capuchin monkeys (Sapajus libidinosus)

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    Foods that are geometrically and mechanically challenging to eat have been associated with specializations in feeding behavior and craniodental morphology across primates, and many of these foods are embedded, requiring a variety of positional behaviors during feeding. However, variation in positional behaviors in response to food properties is not well understood. Here, we examine differences in feeding postural behaviors across feeding events in relation to substrate and food geometric and material properties in a species of extractive foragers, bearded capuchins (Sapajus libidinosus).Methods and materialsWe coded over 1400 co-occurring postural and feeding behaviors, their durations, and relative sizes of substrate and food from videos recorded at Fazenda Boa Vista in Gilbués, Piauí, Brazil. Food material properties were measured from foods collected at the time of the video recordings.ResultsOur results suggest that bearded capuchin feeding postures significantly differ across the feeding sequence, with substrate size, and between foods of high and low toughness and elastic modulus. Feeding postures were less variable for highly mechanically challenging foods. Food size also had a significant effect on postural behaviors. Large foods were more likely to be associated with suspended postures and small foods with sitting and squatting. Feeding postural behaviors were best explained by a combination of substrate and food variables.ConclusionsOur results indicate that food geometric and mechanical properties have a significant influence on feeding postural behaviors in bearded capuchins. We posit that feeding postural behaviors reflect a combination of substrate variables and food properties, and large, mechanically challenging foods have a limiting effect on postural variation.<br

    Food mechanical properties and isotopic signatures in forest versus savannah dwelling eastern chimpanzees

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    Chimpanzees are traditionally described as ripe fruit specialists with large incisors but relatively small postcanine teeth, adhering to a somewhat narrow dietary niche. Field observations and isotopic analyses suggest that environmental conditions greatly affect habitat resource utilization by chimpanzee populations. Here we combine measures of dietary mechanics with stable isotope signatures from eastern chimpanzees living in tropical forest (Ngogo, Uganda) and savannah woodland (Issa Valley, Tanzania). We show that foods at Issa can present a considerable mechanical challenge, most saliently in the external tissues of savannah woodland plants compared to their tropical forest equivalents. This pattern is concurrent with different isotopic signatures between sites. These findings demonstrate that chimpanzee foods in some habitats are mechanically more demanding than previously thought, elucidating the broader evolutionary constraints acting on chimpanzee dental morphology. Similarly, these data can help clarify the dietary mechanical landscape of extinct hominins often overlooked by broad C3/C4 isotopic categories

    The similarity problem for JJ-nonnegative Sturm-Liouville operators

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    Sufficient conditions for the similarity of the operator A:=1/r(x)(−d2/dx2+q(x))A := 1/r(x) (-d^2/dx^2 +q(x)) with an indefinite weight r(x)=(\sgn x)|r(x)| are obtained. These conditions are formulated in terms of Titchmarsh-Weyl mm-coefficients. Sufficient conditions for the regularity of the critical points 0 and ∞\infty of JJ-nonnegative Sturm-Liouville operators are also obtained. This result is exploited to prove the regularity of 0 for various classes of Sturm-Liouville operators. This implies the similarity of the considered operators to self-adjoint ones. In particular, in the case r(x)=\sgn x and q∈L1(R,(1+∣x∣)dx)q\in L^1(R, (1+|x|)dx), we prove that AA is similar to a self-adjoint operator if and only if AA is JJ-nonnegative. The latter condition on qq is sharp, i.e., we construct q∈∩γ<1L1(R,(1+∣x∣)Îłdx)q\in \cap_{\gamma <1} L^1(R, (1+|x|)^\gamma dx) such that AA is JJ-nonnegative with the singular critical point 0. Hence AA is not similar to a self-adjoint operator. For periodic and infinite-zone potentials, we show that JJ-positivity is sufficient for the similarity of AA to a self-adjoint operator. In the case q≡0q\equiv 0, we prove the regularity of the critical point 0 for a wide class of weights rr. This yields new results for "forward-backward" diffusion equations.Comment: 36 pages, LaTeX2e, version 2; addresses of the authors added, the reference [38] update
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