Fast aquatic escape with a jet thruster

The ability to collect water samples rapidly with aerial–aquatic robots would increase the safety and efficiency of water health monitoring and allow water sample collection from dangerous or inaccessible areas. An aquatic micro air vehicle (AquaMAV) able to dive into the water offers a low cost and robust means of collecting samples. However, small-scale flying vehicles generally do not have sufficient power for transition to flight from water. In this paper, we present a novel jet propelled AquaMAV able to perform jumpgliding leaps from water and a planar trajectory model that is able to accurately predict aquatic escape trajectories. Using this model, we are able to offer insights into the stability of aquatic takeoff to perturbations from surface waves and demonstrate that an impulsive leap is a robust method of flight transition. The AquaMAV uses a CO 2 powered water jet to escape the water, actuated by a custom shape memory alloy gas release. The 100 g robot leaps from beneath the surface, where it can deploy wings and glide over the water, achieving speeds above 11 m/s

Plastering the Prehistory: Marl as a unique material to cover, maintain and decorate the Neolithic walls of Catalhöyük.

Çatalhöyük (World Heritage site, c.7400 BC) is a renowned Neolithic site in central Anatolia, Turkey on account of its size, well-preserved mudbrick architecture and wall art. The current international project led by Professor Ian Hodder has been continuing since the 1990’s and the studies showed that people of Çatalhöyük were highly aware of their natural environment and knew how to skillfully modify their resources to develop various material technologies according to their needs. One of the most important material technologies evident at Çatalhöyük makes the site unique within the Neolithic Anatolia and the Near East is the use of ‘Marl’ as a plastering material to cover the internal surfaces of the mudbrick walls. This paper is based on the most recent research undertaken on the technology of the Çatalhöyük wall ‘plasters’ and paintings and will aim to look at what it is meant by ‘plaster and plastering’ in the context of Neolithic Çatalhöyük, identify materials and their characteristics, define the areas of use and terminologies between the different materials and answer some of the controversial questions on the Çatalhöyük wall plasters, such as the use of true lime plaster

Medieval Mortars and the Gothic Revival: The Cosmati Pavement at Westminster Abbey

In the 1870s the architect Sir George Gilbert Scott was appointed Surveyor to the Fabric at Westminster Abbey and one of his major initiatives was to restore the Cosmati Pavement in the Sanctuary. Originally commissioned by Henry III in the late 14th Century, this luxury pavement employed the Cosmatesque technique with materials and possibly artisans imported from Rome. As such, this pavement is the only remaining example if this type north of the Alps, and is one of the very few examples which retains much of its original mortars. These original mortars were developed to cope with the damp conditions of the Thames riverbank and are hydraulic limes which use crushed terracotta as a pozzolana. During the restoration in the 1870s, Gilbert-Scott attempted to replicate the appearance of these materials whilst using contemporary Portland cement mixes with a series of special additives. This paper presents a textural and petrological study, using optical polarising light microscopy, and compares the compositions and manufacturing technologies of the original 14th Century mortars with those of the 19th Century restorations

Ttk69-dependent repression of lozenge prevents the ectopic development of R7 cells in the Drosophila larval eye disc

Background: During the development of the Drosophila eye, specific cell types differentiate from an initially equipotent group of uncommitted precursor cells. The lozenge (lz) gene, which is a member of the Runt family of transcriptional regulators, plays a pivotal role in mediating this process through regulating the expression of several fate-specifying transcription factors. However, the regulation of lz, and the control of lz expression levels in different cell types is not fully understood. Results: Here, we show a genetic interaction between Tramtrack69 (Ttk69) a key transcriptional repressor and an inhibitor of neuronal fate specification, and lz, the master patterning gene of cells posterior to the morphogenetic furrow in the Drosophila eye disc. Loss of Ttk69 expression causes the development of ectopic R7 cells in the third instar eye disc, with these cells being dependent upon Lz for their development. Using the binary UAS Gal4 system, we show that overexpression of Ttk69 causes the loss of lz-dependent differentiating cells, and a down-regulation of Lz expression in the developing eye. The loss of lz-dependent cells can be rescued by overexpressing lz via a GMR-lz transgene. We provide additional data showing that factors functioning upstream of Ttk69 in eye development regulate lz in a Ttk69-dependent manner. Conclusions: Our results lead us to conclude that Ttk69 can either directly or indirectly repress lz gene expression to prevent the premature development of R7 precursor cells in the developing eye of Drosophila. We therefore define a mechanism for the tight regulatory control of the master pre-patterning gene, lz, in early Drosophila eye development and provide insight into how differential levels of lz expression can be achieved to effect specific cell fate outcomes

Ideating IDNA: Lessons and Limitations From Leeches in Legacy Collections

Indirect methods for conducting faunal inventories present great promise, and genomic inventories derived from environmental sources (eDNA) are improving. Invertebrate ingested DNA (iDNA) from terrestrial leeches in the family Haemadipsidae has shown potential for surveying vertebrates and biodiversity monitoring in protected areas. Here we present an initial, and critical, evaluation of the limitations and biases of current iDNA protocols for biodiversity monitoring using both standard and NGS barcoding approaches. Key findings include the need for taxon relevant multi-locus markers and reference databases. In particular, the limitations of available reference databases have profound potential to mislead and bias eDNA and iDNA results if not critically interpreted. Nevertheless, there is great potential for recovery of amplifiable DNA from gut contents of invertebrate museum specimens which may reveal both temporal patterns and cryptic diversity in protected areas with increased efficiency. Our analyses of ingested DNA (iDNA) from both freshly stored and previously collected (legacy) samples of terrestrial leeches successfully identified vertebrates from Myanmar, Australia and Madagascar and indicate the potential to characterize microbial communities, pathogen diversity and interactions at low cost

Are metabolic equivalents (METS) an accurate method for estimating change in peak oxygen consumption after cardiac rehabilitation?

Background: Maximal cardiopulmonary exercise testing (CPET) is the “gold standard” method of determining Vo2peak. When CPET is unavailable, VO2peak and metabolic equivalents (METs) are estimated from treadmill or cycle ergometer workloads. UK cardiac rehabilitation programmes (CR) use estimated METs to report changes in cardiorespiratory fitness (CRF). However, the accuracy of determining changes in VO2peak based on changes in estimated METs is not known. Methods: 27 patients with coronary heart disease (88.9% male; age 59.5 ± 10.0 years, body mass index 29.6 ± 3.8 kg.m-2) performed maximal CPET before and after an exercise based CR intervention. VO2peak was directly determined using ventilatory gas exchange data and was also estimated using the American College of Sports Medicine (ACSM) leg cycling equation for METs. Agreement between changes in directly determined VO2peak and VO2peak estimated from METs was tested using Bland-Altman limits of agreement (LoA), and intraclass correlation coefficients. Results: Directly determined VO2peak did not increase significantly following CR (0.5 ml.kg-1.min-1 (2.7%); p=0.332). In contrast, estimated VO2peak increased significantly (0.4 METs; 1.4 ml.kg-1.min-1; 6.7%; p=0.006). The mean bias for estimated VO2peak versus directly-determined VO2peak was 0.7 ml.kg-1.min-1 (LoA -4.7 to 5.9 ml.kg-1.min-1). Aerobic efficiency, (ΔVO2/ΔWR slope) was significantly associated with estimated VO2peak measurement error. Conclusion: Changes in estimated VO2peak determined using the ACSM equation for leg cycling are not accurate surrogates for directly determined changes in VO2peak. Reporting mean CRF changes using estimated METs may over-estimate the efficacy of CR and lead to a different interpretation of study findings compared to directly determined VO2peak

Thalamic activity and biochemical changes in individuals with neuropathic pain following spinal cord injury

There is increasing evidence relating thalamic changes to the generation and/or maintenance of neuropathic pain. We have recently reported that neuropathic orofacial pain is associated with altered thalamic anatomy, biochemistry, and activity, which may result in disturbed thalamocortical oscillatory circuits. Despite this evidence, it is possible that these thalamic changes are not responsible for the presence of pain per se, but result as a consequence of the injury. To clarify this subject, we compared brain activity and biochemistry in 12 people with below-level neuropathic pain after complete thoracic spinal cord injury with 11 people with similar injuries and no neuropathic pain and 21 age- and gender-matched healthy control subjects. Quantitative arterial spinal labelling was used to measure thalamic activity, and magnetic resonance spectroscopy was used to determine changes in neuronal variability quantifying N-acetylaspartate and alterations in inhibitory function quantifying gamma amino butyric acid. This study revealed that the presence of neuropathic pain is associated with significant changes in thalamic biochemistry and neuronal activity. More specifically, the presence of neuropathic pain after spinal cord injury is associated with significant reductions in thalamic N-acetylaspartate, gamma amino butyric acid content, and blood flow in the region of the thalamic reticular nucleus. Spinal cord injury on its own did not account for these changes. These findings support the hypothesis that neuropathic pain is associated with altered thalamic structure and function, which may disturb central processing and play a key role in the experience of neuropathic pain.NHMR

Giant crystal-electric-field effect and complex magnetic behavior in single-crystalline CeRh3Si2

Single-crystalline CeRh3Si2 was investigated by means of x-ray diffraction, magnetic susceptibility, magnetization, electrical resistivity, and specific heat measurements carried out in wide temperature and magnetic field ranges. Moreover, the electronic structure of the compound was studied at room temperature by cerium core-level x-ray photoemission spectroscopy (XPS). The physical properties were analyzed in terms of crystalline electric field and compared with results of ab-initio band structure calculations performed within the density functional theory approach. The compound was found to crystallize in the orthorhombic unit cell of the ErRh3Si2 type (space group Imma -- No.74, Pearson symbol: oI24) with the lattice parameters: a = 7.1330(14) A, b = 9.7340(19) A, and c = 5.6040(11) A. Analysis of the magnetic and XPS data revealed the presence of well localized magnetic moments of trivalent cerium ions. All physical properties were found to be highly anisotropic over the whole temperature range studied, and influenced by exceptionally strong crystalline electric field with the overall splitting of the 4f1 ground multiplet exceeding 5700 K. Antiferromagnetic order of the cerium magnetic moments at TN = 4.70(1)K and their subsequent spin rearrangement at Tt = 4.48(1) K manifest themselves as distinct anomalies in the temperature characteristics of all investigated physical properties and exhibit complex evolution in an external magnetic field. A tentative magnetic B-T phase diagram, constructed for B parallel to the b-axis being the easy magnetization direction, shows very complex magnetic behavior of CeRh3Si2, similar to that recently reported for an isostructural compound CeIr3Si2. The electronic band structure calculations corroborated the antiferromagnetic ordering of the cerium magnetic moments and well reproduced the experimental XPS valence band spectrum.Comment: 32 pages, 12 figures, to appear in Physical Review

Forum. Stratigraphic Fit to Phylogenies: A Proposed Solution

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73634/1/j.1096-0031.1998.tb00333.x.pd