What makes physiology hard for students to learn? Results of a faculty survey

Teachers of physiology at all postsecondary levels were asked to participate in a survey about the possible sources of students' difficulty in learning physiology. Sixty-three physiology teachers responded to the 18-question survey; 35 of the respondents also responded to a request for written comments about this issue prior to taking the survey. Three categories of possible factors contributing to physiology being hard to learn were defined: 1) the nature of the discipline, 2) the way it is taught, and 3) what students bring to the task of learning physiology. Respondents thought that characteristics of the discipline (it requires causal reasoning, it uses graphs and mathematics, and it is highly integrative) and characteristics of students (they believe that learning and memorizing are the same thing, they cannot or will do attempt to integrate, and they compartmentalize) were significantly more important than any aspect of teaching in making physiology hard to learn. Recommendations are offered in this article to help students deal with the sources of difficulty that were identified.     

What makes a good neighborhood? Interaction of spatial scale and fruit density in the predator satiation dynamics of a masting juniper tree

Spatio-temporal variability in fruit production (masting) has been regarded as a key mechanism to increase plant fitness by reducing seed predation. However, considerably more effort has been devoted into understanding the consequences of temporal rather than spatial variations in fruit crop for plant fitness. In order to simultaneously evaluate both components, we quantify fruit production and pre-dispersal damage by three arthropod species (mites, chalcid wasps and moths) in the Spanish juniper (Juniperus thurifera) during 3 years in a spatially explicit context. Our aims were to assess (1) the interaction between fruit production and pre-dispersal fruit damage by arthropods, (2) the potential interference or competition between arthropods, and (3) the form of the phenotypic selection exerted by arthropods on fruit traits considering the spatial context. Arthropods damaged a substantial fraction of fruits produced by Spanish juniper with levels of damage showing sharp inter-annual variations. Fruit damage by mites was negatively related to yearly fruit crop and positively correlated at individual trees fruiting in consecutive years. Increased interspecific interference was an additional consequence of reduced fruit availability during small crop years. During a masting year, fruit damage by less mobile species such as mites was negatively affected by tree crop size, and no spatial structure was observed for mite damage. The incidence of chalcid wasps was low, so the spatial pattern of seed predation was unclear, and no preferences for fruit or seed traits were detected. Conversely, moths selected larger fruits and their incidence on trees was spatially aggregated up to 20 m, with predation levels being negatively affected by fruit abundance at the patch level, suggesting a positive density-dependent effect of neighbors on fruit output. These results highlight the importance of including the spatial component to understand complex species interactions at local scales.     

What makes a good home for hermits? Assessing gastropod shell density and relative strength

The survival and reproductive success of hermit crabs is intrinsically linked to the quality of their domicile shells. Because damaged or eroded shells can result in greater predation, evaluating shell structure may aid our understanding of population dynamics. We assessed the structural attributes of Cerithium atratum shells through assessments of (a) density using a novel approach involving computed tomography and (b) tolerance to compressive force. Our goal was to investigate factors that may influence decision making in hermit crabs, specifically those that balance the degree of protection afforded by a shell (i.e. density and strength) with the energetic costs of carrying such resources. We compared the density and relative strength (i.e. using compression tests) of shells inhabited by live gastropods, hermit crabs (Pagurus criniticornis) and those found empty in the environment. Results failed to show any relationship between density and shell size, but there was a notable effect of shell density among treatment groups (gastropod/empty/hermit crab). There was also a predictable effect of shell size on maximum compressive force, which was consistent among occupants. Our results suggest that hermit crabs integrate multiple sources of information, selecting homes that while less dense (i.e. reducing the energy costs of carrying these resources), still offer sufficient resistance to compressive forces (e.g. such as those inflicted by shell-breaking predators). Lastly, we show that shell size generally reflects shell strength, thus explaining the motivation of hermit crabs to search for and indeed fight over the larger homes.     

What is mtDNA good for in the study of primate evolution?

Recombinant DNA methods have made accessible the nuclear and organelle genomes of a vast array of plant and animal species.^1–3 Although evolutionary biologists and anthropologists have begun to exploit the full range of these methods, a disproportionate share of this research has centered on the mitochondrial genome (mtDNA). Because of its small size, conserved organization, mode of inheritance, and combination of rapidly and slowly evolving regions, mtDNA (Fig. 1) has appeared in many ways to be the ideal molecule for evolutionary studies of primates.^4,5 However, recent research on higher primates raises serious concerns about the utility of this molecule for evolutionary analysis in the absence of parallel data from the nuclear genome.^6–8 These studies suggest that we need to rethink our research strategies and define more clearly what mtDNA can be used for in the study of primate evolution.     

What is the evidence for the clinical value of SBRT in cancer of the cervix?

AimThe aim of this review is to describe and analyze indications and results of the use of SBRT in uterine cervix cancer, reviewing articles published from January 2010 up to August 2017, for any one of the four indications listed:

• 1Patient refusal or anatomic impediments to interstitial or intracavitary brachytherapy (BCT), i.e. SBRT as an “alternative” for BCT;
• 2Patients with voluminous tumors, or asymmetric tumors where BCT alone would not achieve curative doses, i.e. SBRT as a primary adjunct to BCT;
• 3Pelvic and para aortic adenopathy where SBRT could be used as a boost, i.e. SBRT as a primary adjunct to external beam pelvic radiotherapy;
• 4Small volume recurrences (postoperative or post radiotherapy), i.e. SBRT for salvage.

BackgroundCervix cancer standard treatment involves pelvic irradiation and chemotherapy, recent advances in irradiation techniques might offer new possible approaches.Material and methodsSystematic review of the English language literature about Cervix cancer, SBRT, published from January 2010 to January 2018 identified through a database search of PubMed, and Ovid MEDLINE, using pre-defined search phrases.ResultsThe results in the literature, in general, demonstrate rather weak efficacy of SBRT. In this review, we did not find strong evidence to recommend routine SBRT as a primary treatment for cervico-uterine cancers, i.e. as a replacement for BCT; in highly selected cases it might be considered useful as salvage therapy for relapsed cervix cancer.ConclusionThe existing data to not warrant recommending SBRT for the definitive treatment of cervix cancer, but may have some value in the recurrent/relapsed setting.     

What makes a feather shine? A nanostructural basis for glossy black colours in feathers

Colours in feathers are produced by pigments or by nanostructurally organized tissues that interact with light. One of the simplest nanostructures is a single layer of keratin overlying a linearly organized layer of melanosomes that create iridescent colours of feather barbules through thin-film interference. Recently, it has been hypothesized that glossy (i.e. high specular reflectance) black feathers may be evolutionarily intermediate between matte black and iridescent feathers, and thus have a smooth keratin layer that produces gloss, but not the layered organization of melanosomes needed for iridescence. However, the morphological bases of glossiness remain unknown. Here, we use a theoretical approach to generate predictions about morphological differences between matte and glossy feathers that we then empirically test. Thin-film models predicted that glossy spectra would result from a keratin layer 110-180 nm thick and a melanin layer greater than 115 nm thick. Transmission electron microscopy data show that nanostructure of glossy barbules falls well within that range, but that of matte barbules does not. Further, glossy barbules had a thinner and more regular keratin cortex, as well as a more continuous underlying melanin layer, than matte barbules. Thus, their quasi-ordered nanostructures are morphologically intermediate between matte black and iridescent feathers, and perceived gloss may be a form of weakly chromatic iridescence.     

What makes a cry a cry? A review of infant distress vocalizations

In contrast to the cries of human infants,sounds made by non-human infants in different stressful behavioral contexts (hunger or physical discomfort,isolation,capture by humans or predators) are usually treated as distinct types of vocalizations.However,if distress vocalizations produced by different species and in different contexts share a common motivational state and associated neurochemical pathways,we can expect them to share a common acoustic structure and adaptive function,showing only limited variation that corresponds to the infant's level of arousal.Based on this premise,we review the acoustic structure and adaptive function of two types of distress calls,those given when infants were isolated from their mothers (isolation calls) or captured by humans (capture calls).We conducted a within-context comparison examining the two call types across a diverse selection of mammalian species and other vertebrate groups,followed by a comparison of how acoustic structure and function differs between these contexts.In addition,we assessed acoustic traits that are critical to the response of caregivers.Across vertebrate species,distress vocalizations produced in these two behavioral contexts tend to be tonal with a simple chevron,flat or descending pattern of frequency modulation.Reports that both isolation and capture calls of vertebrate infants serve to attract caregivers are universal,and the fundamental frequency of infant vocalizations is often critical to this response.The results of our review are consistent with the hypothesis that differences in the acoustic structure of isolation and capture distress vocalizations reflect differences in arousal,and not discrete functions.The similarity in acoustic structure and caregiver response observed across vertebrates adds support to the hypothesis that the production and processing of distress vocalizations are part of a highly-conserved system of social vocal behaviour in vertebrates.Bioacoustic research may move forward by recognizing the commonality among different forms of infant solicitations that attract caregivers,and the commonality of these solicitations with vocalizations that attract conspecifics in still other behavioral contexts.     

What are definitions of life good for? Transdisciplinary and other definitions in astrobiology

The attempt to define life has gained new momentum in the wake of novel fields such as synthetic biology, astrobiology, and artificial life. In a series of articles, Cleland, Chyba, and Machery claim that definitions of life seek to provide necessary and sufficient conditions for applying the concept of life—something that such definitions cannot, and should not do. We argue that this criticism is largely unwarranted. Cleland, Chyba, and Machery approach definitions of life as classifying devices, thereby neglecting their other epistemic roles. We identify within the discussions of the nature and origin of life three other types of definitions: theoretical, transdisciplinary, and diagnostic definitions. The primary aim of these definitions is not to distinguish life from nonlife, although they can also be used for classificatory purposes. We focus on the definitions of life within the budding field of astrobiology, paying particular attention to transdisciplinary definitions, and diagnostic definitions in the search for biosignatures from other planets.     

What makes an aquaporin a glycerol channel? A comparative study of AqpZ and GlpF

The recent availability of high-resolution structures of two structurally highly homologous, but functionally distinct aquaporins from the same species, namely Escherichia coli AqpZ, a pure water channel, and GlpF, a glycerol channel, presents a unique opportunity to understand the mechanism of substrate selectivity in these channels. Comparison of the free energy profile of glycerol conduction through AqpZ and GlpF reveals a much larger barrier in AqpZ (22.8 kcal/mol) than in GlpF (7.3 kcal/mol). In either channel, the highest barrier is located at the selectivity filter. Analysis of substrate-protein interactions suggests that steric restriction of AqpZ is the main contribution to this large barrier. Another important difference is the presence of a deep energy well at the periplasmic vestibule of GlpF, which was not found in AqpZ. The latter difference can be attributed to the more pronounced structural asymmetry of GlpF, which may play a role in attracting glycerol.     

Towards an updated ESTRO-EFOMP core curriculum for education and training of medical physics experts in radiotherapy – A survey of current education and training practice in Europe

PurposeESTRO-EFOMP intend to update the core curriculum (CC) for education and training of medical physicists in radiotherapy in line with the European Commission (EC) guidelines on Medical Physics Experts (MPE), the CanMEDS methodology and recent developments in radiotherapy. As input, a survey of the current structure of radiotherapy MPE national training schemes (NTS) in Europe was carried out.MethodsA 35-question survey was sent to all European medical physics national societies (NS) with a focus on existence of an NTS, its format and duration, required entry-level education, and financial support for trainees.ResultsTwenty-six of 36 NS responded. Twenty had an NTS. Minimum required pre-training education varied from BSc in physics or related sciences (5/2) to MSc in medical physics, physics or related sciences (6/5/2) with 50–210 ECTS in fundamental physics and mathematics. The training period varied from 1 to 5 years (median 3 years with 50% dedicated to radiotherapy). The ratio of time spent on university lectures versus hospital training was most commonly 25%/75%. In 14 of 20 countries with an NTS, a research project was mandatory. Residents were paid in 17 of 20 countries. The recognition was mostly obtained by examination. Medical physics is recognised as a healthcare profession in 19 of 26 countries.ConclusionsThe NTS entrance level, duration and curriculum showed significant variations. This survey serves to inform the design of the updated CC to define a realistic minimum training level for safe and effective practice aiming at further harmonization in line with EC guidelines.     

What makes a gene name? Named entity recognition in the biomedical literature

The recognition of biomedical concepts in natural text (named entity recognition, NER) is a key technology for automatic or semi-automatic analysis of textual resources. Precise NER tools are a prerequisite for many applications working on text, such as information retrieval, information extraction or document classification. Over the past years, the problem has achieved considerable attention in the bioinformatics community and experience has shown that NER in the life sciences is a rather difficult problem. Several systems and algorithms have been devised and implemented. In this paper, the problems and resources in NER research are described, the principal algorithms underlying most systems sketched, and the current state-of-the-art in the field surveyed.