Arthropods on Mars?

As presented in this report numerous fossils like forms resembling a variety of marine arthropods including crustaceans, sea spiders, scorpions, arachnids, nematodes, annelids, tube worms, sea snakes, Kimberlla, Namacalathus, Lophotrochozoa, armored trilobites and millipedes have been found in Gale Crater (on Sols 302, 553, 753, 781, 809, 869, 880, 905, 1032), and Meridiani Planum both of which have hosted rivers, lakes, and inland seas. Similar specimens are mixed within a variety of divergent fossillike forms and are also found on distant sediment and mud stone. All specimens are distinct from underlying substrate and there are no obvious patterns or repetitions typically produced by erosion or weathering. Although without extraction and direct examination it is impossible to precisely determine the identity of all these specimens, the same problems bedevil identification of Burgess Shale fossils some of which are presented in this report for comparative analysis. The discoveries presented here and in other reports supports the theory that metazoans and other marine organisms evolved in the lakes, oceans and inland seas of Mars

Altered developmental programs and oriented cell divisions lead to bulky bones during salamander limb regeneration

There are major differences in duration and scale at which limb development and regeneration proceed, raising the question to what extent regeneration is a recapitulation of development. We address this by analyzing skeletal elements using a combination of micro-CT imaging, molecular profiling and clonal cell tracing. We find that, in contrast to development, regenerative skeletal growth is accomplished based entirely on cartilage expansion prior to ossification, not limiting the transversal cartilage expansion and resulting in bulkier skeletal parts. The oriented extension of salamander cartilage and bone appear similar to the development of basicranial synchondroses in mammals, as we found no evidence for cartilage stem cell niches or growth plate-like structures during neither development nor regeneration. Both regenerative and developmental ossification in salamanders start from the cortical bone and proceeds inwards, showing the diversity of schemes for the synchrony of cortical and endochondral ossification among vertebrates

Interaction of the tetracyclines with double-stranded RNAs of random base sequence: new perspectives on the target and mechanism of action

The 16S rRNA binding mechanism proposed for the antibacterial action of the tetracyclines does not explain their mechanism of action against non-bacterial pathogens. In addition, several contradictory base pairs have been proposed as their binding sites on the 16S rRNA. This study investigated the binding of minocycline and doxycycline to short double-stranded RNAs (dsRNAs) of random base sequences. These tetracyclines caused a dose-dependent decrease in the fluorescence intensities of 6-carboxyfluorescein (FAM)-labelled dsRNA and ethidium bromide (EtBr)-stained dsRNA, indicating that both drugs bind to dsRNA of random base sequence in a manner that is competitive with the binding of EtBr and other nucleic acid ligands often used as stains. This effect was observable in the presence of Mg2+. The binding of the tetracyclines to dsRNA changed features of the fluorescence emission spectra of the drugs and the CD spectra of the RNA, and inhibited RNase III cleavage of the dsRNA. These results indicate that the double-stranded structures of RNAs may have a more important role in their interaction with the tetracyclines than the specific base pairs, which had hitherto been the subject of much investigation. Given the diverse functions of cellular RNAs, the binding of the tetracyclines to their double-stranded helixes may alter the normal processing and functioning of the various biological processes they regulate. This could help to explain the wide range of action of the tetracyclines against various pathogens and disease condition

The Immune System in Stroke

Stroke represents an unresolved challenge for both developed and developing countries and has a huge socio-economic impact. Although considerable effort has been made to limit stroke incidence and improve outcome, strategies aimed at protecting injured neurons in the brain have all failed. This failure is likely to be due to both the incompleteness of modelling the disease and its causes in experimental research, and also the lack of understanding of how systemic mechanisms lead to an acute cerebrovascular event or contribute to outcome. Inflammation has been implicated in all forms of brain injury and it is now clear that immune mechanisms profoundly influence (and are responsible for the development of) risk and causation of stroke, and the outcome following the onset of cerebral ischemia. Until very recently, systemic inflammatory mechanisms, with respect to common comorbidities in stroke, have largely been ignored in experimental studies. The main aim is therefore to understand interactions between the immune system and brain injury in order to develop novel therapeutic approaches. Recent data from clinical and experimental research clearly show that systemic inflammatory diseases -such as atherosclerosis, obesity, diabetes or infection - similar to stress and advanced age, are associated with dysregulated immune responses which can profoundly contribute to cerebrovascular inflammation and injury in the central nervous system. In this review, we summarize recent advances in the field of inflammation and stroke, focusing on the challenges of translation between pre-clinical and clinical studies, and potential anti-inflammatory/immunomodulatory therapeutic approaches

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

CEO transformational leadership and top management team performance: study from GCC

Purpose: Various research studies have been carried out to study Chief Executive Officers (CEOs) transformational leadership in driving organizational performance and success. Evidence shows that few studies were carried out on CEO transformational leadership and top management team (TMT) performance in Gulf Cooperation Council (GCC) region. Thus, this study aims to provide a unique contribution and the first of its kind to examine the CEO leadership TMT performance link across GCC countries. Design/methodology/approach: In this study, the researchers approached 500 employees and 30 CEOs working in 30 different organizations operating in the GCC countries. The firms were selected conveniently from different industries located in the UAE, Saudi Arabia, Kuwait, Oman and Bahrain. The researchers used the PASW (SPSS) program to analyze the data. Findings: The findings show that psychological empowerment has no significant role in moderating the transformational leadership TMT performance relationship. Internal support for innovation plays a significant role in mediating the relationship between transformational leadership and TMT performance. Research limitations/implications: The present study has not examined the behavioral aspects of CEO followers. Future research may study behavioral characteristics of the entire TMT. Originality/value: This study contributes to body of research that identifies CEO transactional leadership as perceived by the followers was found to be more important in predicting TMT performance than transformational leadership in the context of organizations located in GCC countries. Managerial implications and future research areas are further discussed.Scopu

CHARGE PUMPING IN SILICON ON INSULATOR STRUCTURES USING GATED P-I-N DIODES

Nous présentons une extension de la technique de pompage de charge sur des diodes P+IN+ à grille de contrôle, fabriquées sur silicium sur isolant. Cette méthode nous permet d'accéder aux propriétés des interfaces des structures SOS et SIMOX, tout en évitant l'utilisation de transistors MOS à 5 contacts. Les mesures effectuées sur SIMOX en pulsant la grille et/ou le substrat révèlent l'existence d'une forte densité d'états d'interface rapides et de pièges volumiques au voisinage de l'oxyde enterré.The extension of the charge pumping technique to gated P+IN+ diodes fabricated on silicon on insulator is analysed. This method allows us to evaluate the interface properties in SOS and SIMOX structures, without the need for 5-terminal MOS transistors. The experiment, performed on SIMOX films by pulsing both the gate and substrate, reveal the existence of a high density of fast interface states and bulk traps near the buried oxide