The solar flare and cosmic gamma-ray burst experiment aboard the Ulysses spacecraft

The HUS-Ulysses team has prepared an instrument for the Ulysses spacecraft consisting of 2 Csi detectors and 2 Si surface barrier detectors for measuring x rays in the range 5 to 200 keV with up to 8 ms time resolution. The prime objectives of the experiment are the study of solar flares and cosmic gamma-ray bursts. The Ulysses mission will leave the ecliptic during the forthcoming solar maximum. The total time above ecliptic latitudes + or - 70 degrees is expected to be 230 days. The solar data can be used in conjunction with other experiments to measure the directivity of the emission and for correlative studies

The extensive age gradient of the Carina dwarf galaxy

The evolution of small systems such as dwarf spheroidal galaxies (dSph) is likely to have been a balance between external environmental effects and internal processes within their own relatively shallow potential wells. Assessing how strong such environmental interactions may have been is therefore an important element in understanding the baryonic evolution of dSphs and their derived dark matter distribution. Here we present results from a wide-area CTIO/MOSAIC II photometric survey of the Carina dSph, reaching down to about two magnitudes below the oldest main sequence turn-off (MSTO). This data-set enables us to trace the structure of Carina in detail out to very large distances from its center, and as a function of stellar age. We observe the presence of an extended structure made up primarily of ancient MSTO stars, at distances between 25arcmin-60arcmin from Carina's center, confirming results in the literature that Carina extends well beyond its nominal tidal radius. The large number statistics of our survey reveals features such as isophote twists and tails that had gone undetected in other previous shallower surveys. This is the first time that such unambiguous signs of tidal disruption have been found in a Milky Way "classical" dwarf other than Sagittarius. We also demonstrate the presence of a negative age gradient in Carina directly from its MSTOs, and trace it out to very large distances from the galaxy center. The signs of interaction with the Milky Way make it unclear whether the age gradient was already in place before Carina underwent tidal disruption.Comment: Accepted for publication in The Astrophysical Journal Letter

The black silicon method: a universal method for determining the parameter setting of a fluorine-based reactive ion etcher in deep silicon trench etching with profile control

Very deep trenches (up to 200 µm) with high aspect ratios (up to 10) in silicon and polymers are etched using a fluorine-based plasma (SF6/O2/CHF3). Isotropic, positively and negatively (i.e. reverse) tapered as well as fully vertical walls with smooth surfaces are achieved by controlling the plasma chemistry. A convenient way to find the processing conditions needed for a vertical wall is described: the black silicon method. This new procedure is checked for three different reactive ion etchers (RIE), two parallel-plate reactors and a hexode. The influence of the RF power, pressure and gas mixture on the profile will be shown. Scanning electron microscope (SEM) photos are included to demonstrate the black silicon method, the influence of the gases on the profile, and the use of this method in fabricating microelectromechanical systems (MEMS)

Lorentz shift measurements in heavily irradiated silicon detectors in high magnetic fields

An external magnetic field exerts a Lorentz force on drifting electric charges inside a silicon strip sensor and thus shifts the cluster position of the collected charge. The shift can be related to the Lorentz angle which is typically a few degrees for holes and a few tens of degrees for electrons in a 4 T magnetic field. The Lorentz angle depends upon magnetic field, electric field inside the sensor and temperature. In this study the sensitivity to radiation for fluences up to 10^16 n/cm^2 has been studied. The Lorentz shift has been measured by inducing ionization with 670 nm red or 1070 nm infrared laser beams injected into the back side of the irradiated silicon sensor operated in magnetic fields up to 8 T. For holes the shift as a function of radiation is increasing, while for electrons it is decreasing and even changes sign. The fact that for irradiated sensors the Lorentz shift for electrons is smaller than for holes, in contrast to the observations in non-irradiated sensors, can be qualitatively explained by the structure of the electric field in irradiated sensors.Comment: Accepted publication for RD09 conference in Proceedings of Scienc

Fully broadband vAPP coronagraphs enabling polarimetric high contrast imaging

We present designs for fully achromatic vector Apodizing Phase Plate (vAPP) coronagraphs, that implement low polarization leakage solutions and achromatic beam-splitting, enabling observations in broadband filters. The vAPP is a pupil plane optic, inducing the phase through the inherently achromatic geometric phase. We discuss various implementations of the broadband vAPP and set requirements on all the components of the broadband vAPP coronagraph to ensure that the leakage terms do not limit a raw contrast of 1E-5. Furthermore, we discuss superachromatic QWPs based of liquid crystals or quartz/MgF2 combinations, and several polarizer choices. As the implementation of the (broadband) vAPP coronagraph is fully based on polarization techniques, it can easily be extended to furnish polarimetry by adding another QWP before the coronagraph optic, which further enhances the contrast between the star and a polarized companion in reflected light. We outline several polarimetric vAPP system designs that could be easily implemented in existing instruments, e.g. SPHERE and SCExAO.Comment: 11 pages, 5 figures, presented at SPIE Astronomical Telescopes and Instrumentation 201

Probing F-theory With Multiple Branes

We study multiple 3-branes on an F theory orientifold. The world-volume theory of the 3-branes is d=4, N=2 Sp(2k) gauge theory with an antisymmetric tensor and four flavors of matter in the fundamental. The solution of this gauge theory is found for vanishing bare mass of the antisymmetric tensor matter, and massive fundamental matter. The integrable system underlying this theory is constructed.Comment: 9 pages, harvma

Segmentation and Feature Extraction of Human Gait Motion

This paper presents segmentation and feature extraction of human gait motion. The methodology of this paper focuses on segmenting ‘XYZ’ position curves, in reference to time of gait motion based on the velocity or acceleration of the movement. The extracted features include amplitude, time, and equally spaced sample data, maximum and minimum for each segment. The results can be used for reconstruction of a viable dataset that is critical for simulation and validation of human gaits. We propose a method to enables the fitting of the same curve with limited data. Such data sets may prove valuable for studying impairments and improving simulations of rehabilitation tools, and statistical classification for researchers worldwide

TBP binding and the rate of transcription initiation from the human β-globin gene.

DNA-protein interaction studies in vitro revealed several factors binding over the TATA box and the region of transcription initiation (cap) site of the human beta-globin promoter; TATA binding protein TBP at -30, Sp1 at -19, GATA-1 at -12 and +5, YY1 at -9 and a novel factor C1 over the site of initiation (-4 to +7). Point mutants which specifically abolish the binding of each of these proteins were tested in a beta-globin locus control region (LCR) construct which allows quantitative comparisons at physiological levels of transcription. Only mutants which drastically affect the binding of TBP resulted in decreased levels of transcription. A threshold value of TBP binding of 15-30% of wild type was sufficient to give normal levels of transcription. This indicates that the association of TF IID with the TATA box is not limiting in the rate of initiation of transcription

Conceptual design of a light sport aircraft

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering by course work and research project. Johannesburg, May 2016The design of a conceptual aircraft was required to fulfil the recreational and commercial flight training roles as part of a rural development initiative. The regulations regarding the airworthiness of aircraft and the South African microlight and ultralight aircraft market were investigated to determine the niche performance requirements. The large sales enjoyed by the new Light Sport Aircraft (LSA) category created an opportunity to design an aircraft conforming to both the non-prescriptive ultralight and prescriptive LSA consensus standards. This would allow the aircraft be used in several countries. The best practices regarding design for manufacture used in industry were investigated to create a framework of consideration for the detailed design of the aircraft. The performance of the market leading ultralight and LSA was analysed. The Cessna C-162 Skycatcher and Tecnam P-92 were investigated as the main competitors. Flight speed, payload, structural efficiency and aerodynamic efficiency were analysed to set target performance requirements. The aircraft was required to have a minimum power utilisation of 1.05kt/hp, minimum useful load of 250kg and a minimum cruise speed of 110kts. The aircraft was constrained to a 100hp engine. These performance user requirements were used with cost, environmental and operational requirements to design a high-level concept. The concept was developed so that each major system on the aircraft had been designed to create a complete concept. The method used to develop several concepts for several systems and assess them against the user requirements was developed from the dialectic engine principle of destruction and creation. This process was performed simultaneously. The systems were broken into basic principles and components before being creatively integrated into improved systems. Three design features were generated and patented. The designs included a propeller spinner that assisted with air induction for better cooling, a winglet to assist with breakdown of wake vortices and an excrescence free flap system for a light aircraft. The only design used on this aircraft was the flap system. The aircraft concept was further refined using the same destruction and creation synthesis technique. The concept aircraft was the subject of a detailed business plan and launch strategy that would use the aircraft to leverage funding to start a new industry in the Eastern Cape province. The performance of the aircraft concept was calculated using standard performance techniques that were modified for use, based on experience with other light aircraft. The major emphasis was on the energy available to accelerate, climb and turn. The method developed to analyse a descending turn without power was used to demonstrate that the aircraft could manoeuvre better than the competitors at low power settings. The energy levels needed to surpass the competition were used to design an aircraft with a significant energy margin at speeds of 65-85KCAS, making the aircraft ideal for flight training. The aircraft was designed with a higher aspect ratio and lower wing loading than the competitors to achieve better energy levels and better performance in hot and high conditions. The reduction in maximum speed was not significant when compared to the turn and manoeuvre performance. The structure of the aircraft was then designed to withstand the loads prescribed by the consensus standards. The aircraft was shown to comply with the standards. The completion of the structural design of the major components allowed for the design to be costed. The business plan was revised to include the cost of the manufacturing facility and total investment cost required to realise the project. The proposer of the project funded a full-size mock-up of the aircraft that was launched at a major airshow. The regulatory framework of regulations and technical standards was extensively revised, making the process of obtaining production-built type approval for a design less onerous. Recommendations for structural testing and transient energy analysis were made.MT201

A Pharmacokinetic Model for Protamine Dosing After Cardiopulmonary Bypass

ObjectiveThis study investigated postoperative hemostasis of patients subjected to conventional protamine dosing compared with protamine dosing based on a pharmacokinetic (PK) model following cardiopulmonary bypass.DesignRetrospective case-control study.SettingTertiary university hospital.ParticipantsPatients undergoing elective cardiac surgery with cardiopulmonary bypass.InterventionsIn 56 patients, protamine was dosed in a fixed ratio (CD), while 62 patients received protamine based on the PK model.Measurements and Main ResultsThere was no difference in heparin administration (414±107 mg (CD) v 403±90 mg (PK); p = 0.54), whereas protamine dosing was considerably different with a protamine-to-heparin dosing ratio of 1.1±0.3 for the CD group and 0.5±0.1 for the PK group (p<0.001). The changes in activated coagulation time (ΔACT) values (ACT after protamine minus preoperative ACT;+17±77 s v+6±15 s; p = 0.31) were equal between groups. Yet, the thromboelastometric intrinsically activated coagulation test clotting time (CT; 250±76 s v 203±44 s; p<0.001) and intrinsically activated coagulation test without the heparin effect CT (275±105 v 198±32 s; p<0.001) were prolonged in the CD group. Median packed red blood cell transfusion (0 [0–2] v 0 [0–0]), fresh frozen plasma transfusion (1 [0–2] v 0 [0–0]), and platelet concentrate transfusion (0 [0–1] v 0 [0–0]) were different between the fixed ratio and PK group, respectively (all p<0.001).ConclusionsThis study showed that patient-tailored protamine dosing based on a PK model was associated with a reduction in protamine dosing, with better hemostatic test results when compared with fixed-ratio protamine dosing