Hormonal interactions in the control of Arabidopsis hypocotyl elongation

The Arabidopsis hypocotyl, together with hormone mutants and chemical inhibitors, was used to study the role of auxin iri cell elongation and its possible interactions with ethylene and gibberellin. When wild-type Arabidopsis seedlings were grown on media containing a range of auxin concentrations, hypocotyl growth was inhibited. However, when axr1-12 and 35S-iaaL (which have reduced auxin response and levels, respectively) were grown in the same conditions, auxin was able to promote hypocotyl growth. In contrast, auxin does not promote hypocotyl growth of axr3-1, which has phenotypes that suggest an enhanced auxin response. These results are consistent with the hypothesis that auxin levels in the wild-type hypocotyl are optimal for elongation and that additional auxin is inhibitory. When ethylene responses were reduced using either the ethylene-resistant mutant etr1 or aminoethoxyvinylglycine, an inhibitor of ethylene synthesis, auxin responses were unchanged, indicating that auxin does not inhibit hypocotyl elongation through ethylene. To test for interactions between auxin and gibberellin, auxin mutants were grown on media containing gibberellin and gibberellin mutants were grown on media containing auxin. The responses were found to be the same as wild-type Arabidopsis seedlings in all cases. In addition, 1 muM of the auxin transport inhibitor 1-naphthylphthalmic acid does not alter the response of wild-type seedlings to gibberellin. Double mutants were made between gibberellin and auxin mutants and the phenotypes of these appear additive. These results indicate that auxin and gibberellin are acting independently in hypocotyl elongation. Thus auxin, ethylene, and gibberellin each regulate hypocotyl elongation independently

Influence of biochar composition and source material on catalytic performance : the carboxylation of glycerol with CO2 as a case study

The impact of the chemical and physical composition of biochar catalysts is demonstrated in the carboxylation of glycerol with carbon dioxide for the first time, using acetonitrile as a dehydrating agent. Biochars are an important emerging class of catalytic material that can readily be produced from low-value biomass residues; however, the impact of feedstock choice is often overlooked. The ash content of biochar from three different feedstocks is shown to be catalytically active for the production of glycerol carbonate and triacetin, whilst low-ash catalysts such as soft wood biochar and commercial activated charcoal are inactive. Following treatment with hydrochloric acid, yields of glycerol carbonate over ash were reduced by over 94%, and triacetin was no longer produced. This has been attributed to the loss of potassium content. Carbon content was shown to be catalytically active for the synthesis of diacetin, and graphitic carbon may be beneficial. Through the development of structure–performance relationships, biomass feedstocks with the most suitable properties can therefore be selected to produce biochars for specific catalytic applications. This would expand the range of reactions which can be effectively catalysed by these materials and enhance the development of a more circular and sustainable chemicals industry

Polarization and decoherence in a two-component Bose-Einstein Condensate

We theoretically investigate polarization properties of a two-component Bose-Einstein condensate (BEC) and influence of decoherence induced by environment on BEC polarization through introducing four BEC Stokes operators which are quantum analog of the classical Stokes parameters for a light field. BEC polarization states can be geometrically described by a Poincar\'{e} sphere defined by expectation values of BEC Stokes operators. Without decoherence, it is shown that nonlinear inter-atomic interactions in the BEC induce periodic polarization oscillations whose periods depend on the difference between self-interaction in each component and inter-component interaction strengths. In particular, when inter-atomic nonlinear self-interaction in each BEC component equals inter-component nonlinear interaction, Stokes vector associated with Stokes operators precesses around a fixed axis in the dynamic evolution of the BEC. The value of the processing frequency is determined by the strength of the linear coupling between two components of the BEC. When decoherence is involved, we find each component of the Stokes vector decays which implies that decoherence depolarizes the BEC.Comment: 10 pages, 2 figure

Separating Reflection and Transmission Images in the Wild

The reflections caused by common semi-reflectors, such as glass windows, can impact the performance of computer vision algorithms. State-of-the-art methods can remove reflections on synthetic data and in controlled scenarios. However, they are based on strong assumptions and do not generalize well to real-world images. Contrary to a common misconception, real-world images are challenging even when polarization information is used. We present a deep learning approach to separate the reflected and the transmitted components of the recorded irradiance, which explicitly uses the polarization properties of light. To train it, we introduce an accurate synthetic data generation pipeline, which simulates realistic reflections, including those generated by curved and non-ideal surfaces, non-static scenes, and high-dynamic-range scenes.Comment: accepted at ECCV 201

Achromatizing a liquid-crystal spectropolarimeter: Retardance vs Stokes-based calibration of HiVIS

Astronomical spectropolarimeters can be subject to many sources of systematic error which limit the precision and accuracy of the instrument. We present a calibration method for observing high-resolution polarized spectra using chromatic liquid-crystal variable retarders (LCVRs). These LCVRs allow for polarimetric modulation of the incident light without any moving optics at frequencies >10Hz. We demonstrate a calibration method using pure Stokes input states that enables an achromatization of the system. This Stokes-based deprojection method reproduces input polarization even though highly chromatic instrument effects exist. This process is first demonstrated in a laboratory spectropolarimeter where we characterize the LCVRs and show example deprojections. The process is then implemented the a newly upgraded HiVIS spectropolarimeter on the 3.67m AEOS telescope. The HiVIS spectropolarimeter has also been expanded to include broad-band full-Stokes spectropolarimetry using achromatic wave-plates in addition to the tunable full-Stokes polarimetric mode using LCVRs. These two new polarimetric modes in combination with a new polarimetric calibration unit provide a much more sensitive polarimetric package with greatly reduced systematic error.Comment: Accepted in PAS

Wood ants learn the magnetic direction of a route but express uncertainty because of competing directional cues

Wood ants were trained indoors to follow a magnetically specified route that went from the centre of an arena to a drop of sucrose at the edge. The arena, placed in a white cylinder, was in the centre of a 3D coil system generating an inclined Earth-strength magnetic field in any horizontal direction. The specified direction was rotated between each trial. The ants' knowledge of the route was tested in trials without food. Tests given early in the day, before any training, show that ants remember the magnetic route direction overnight. During the first 2 s of a test, ants mostly faced in the specified direction, but thereafter were often misdirected, with a tendency to face briefly in the opposite direction. Uncertainty about the correct path to take may stem in part from competing directional cues linked to the room. In addition to facing along the route, there is evidence that ants develop magnetically directed home and food vectors dependent upon path integration. A second experiment asked whether ants can use magnetic information contextually. In contrast to honeybees given a similar task, ants failed this test. Overall, we conclude that magnetic directional cues can be sufficient for route learning

Modeling the Searching Behavior of Social Monkeys

We discuss various features of the trajectories of spider monkeys looking for food in a tropical forest, as observed recently in an extensive {\it in situ} study. Some of the features observed can be interpreted as the result of social interactions. In addition, a simple model of deterministic walk in a random environment reproduces the observed angular correlations between successive steps, and in some cases, the emergence of L\'evy distributions for the length of the steps.Comment: 7 pages, 3 figure

The transition from medical student to junior doctor: today's experiences of Tomorrow's Doctors.

CONTEXT Medical education in the UK has recently undergone radical reform. Tomorrow's Doctors has prescribed undergraduate curriculum change and the Foundation Programme has overhauled postgraduate education. OBJECTIVES This study explored the experiences of junior doctors during their first year of clinical practice. In particular, the study sought to gain an understanding of how junior doctors experienced the transition from the role of student to that of practising doctor and how well their medical school education had prepared them for this. METHODS The study used qualitative methods comprising of semi-structured interviews and audio diary recordings with newly qualified doctors based at the Peninsula Foundation School in the UK. Purposive sampling was used and 31 of 186 newly qualified doctors self-selected from five hospital sites. All 31 participants were interviewed once and 17 were interviewed twice during the year. Ten of the participants also kept audio diaries. Interview and audio diary data were transcribed verbatim and thematically analysed with the aid of a qualitative data analysis software package. RESULTS The findings show that, despite recent curriculum reforms, most participants still found the transition stressful. Dealing with their newly gained responsibility, managing uncertainty, working in multi-professional teams, experiencing the sudden death of patients and feeling unsupported were important themes. However, the stress of transition was reduced by the level of clinical experience gained in the undergraduate years. CONCLUSIONS Medical schools need to ensure that students are provided with early exposure to clinical environments which allow for continuing 'meaningful' contact with patients and increasing opportunities to 'act up' to the role of junior doctor, even as students. Patient safety guidelines present a major challenge to achieving this, although with adequate supervision the two aims are not mutually exclusive. Further support and supervision should be made available to junior doctors in situations where they are dealing with the death of a patient and on surgical placements