Southern Hemisphere Observations of a 101810^{18}eV Cosmic Ray Source Near the Direction of the Galactic Centre

We report on an analysis of data from the southern hemisphere SUGAR cosmic ray detector. We confirm the existence of an excess of $10^{18}$eV cosmic rays from a direction close to the Galactic Centre, first reported by the AGASA group. We find that the signal is consistent with that from a point source, and we find no evidence for an excess of cosmic rays coming from the direction of the Galactic Centre itself.Comment: 14 pages including 5 postscript figures, corrected the title (replaced "Cosmic Ray Source" instead of "Cosmic Ray"

Low-order methods for the unsteady aerodynamics of finite wings

The development of modern unmanned aerial vehicles, high-altitude long-endurance drones, wind turbines, energy harvesting devices and micro air vehicles all require the consideration of unsteady aerodynamics. Unsteady flow simulation is not only more computationally expensive than steady simulations, but the unsteadiness expands the range of relevant parameters to be considered. This makes the use of traditional unsteady computational fluid dynamics methods too computationally expensive for many applications. Low-order methods provide an alternative. By neglecting less important aspects of the problem being solved, the cost of obtaining a solution can be greatly reduced. However, currently available low-order methods are limited by being either too narrow in the phenomena they model, still too computationally expensive, or not sufficiently well understood to be used with confidence. In this dissertation, low-order methods for the unsteady aerodynamics of finite wings are investigated. Uncertainties around Unsteady Lifting-Line Theory (ULLT) are resolved and new methods are derived where existing methods are either too slow or do not exist. This thesis primarily studies ULLT. ULLT allows a problem to be modelled as interacting two-dimensional problems, reducing the cost of obtaining a solution. This approach is applied to Euler cases and low Reynolds number (Re = 10 000) cases for both sinusoidal oscillation kinematics and arbitrary kinematics. Small and large amplitude kinematics are investigated, with large amplitudes introducing additional complications including leading-edge vortex structures. Frequency-domain problems are initially considered in the Euler regime using frequency domain ULLT. It is shown that existing methods produce good solutions when the assumptions made in their derivation are satisfied. For low Reynolds number cases, where their assumptions are violated, they still provide reasonable accuracy, even in the presence of aerodynamic non-linearities. Frequency-domain methods are then applied to time-domain problems using a new, low-computational-cost method. It is shown how Fourier transforms can be used to obtain solutions for arbitrary input kinematics. Some of the limitations of this method are then alleviated with a new time-marching geometrically non-linear ULLT. However, this method cannot model the leading-edge vortex. For that, another new method is obtained, based on the 3D vortex particle method

Unsteady lifting-line theory and the influence of wake vorticity on aerodynamic loads

Frequency-domain unsteady lifting-line theory (ULLT) provides a means by which the aerodynamics of oscillating wings may be studied at low computational cost without neglecting the interacting effects of aspect ratio and oscillation frequency. Renewed interest in the method has drawn attention to several uncertainties however. Firstly, to what extent is ULLT practically useful for rectangular wings, despite theoretical limitations? And secondly, to what extent is a complicated wake model needed in the outer solution for good accuracy? This paper aims to answer these questions by presenting a complete ULLT based on the work of Sclavounos, along with a novel ULLT that considers only the streamwise vorticity and a Prandtl-like pseudosteady ULLT. These are compared to Euler CFD for cases of rectangular wings at multiple aspect ratios and oscillation frequencies. The results of this work establish ULLT as a low computational cost model capable of accounting for interacting finite-wing and oscillation frequency effects and identify the aspect ratio and frequency regimes where the three ULLTs are most accurate. This research paves the way towards the construction of time-domain or numerical ULLTs which may be augmented to account for nonlinearities such as flow separation

Applying frequency-domain unsteady lifting-line theory to time-domain problems

Frequency-domain unsteady lifting-line theory is better developed than its time-domain counterpart. To take advantage of this, this paper proposes a method to transform time-domain kinematics to the frequency domain, perform a convolution, and then return the results back to the time domain. This paper demonstrates how well-developed frequency-domain methods can be easily applied to time-domain problems, enabling prediction of forces and moments on finite wings undergoing arbitrary kinematics. Results are presented for rectangular wings of various aspect ratios, undergoing pitch and heave kinematics. Computational fluid dynamics is used to test the effectiveness of the method in the Euler and low-Reynolds-number (Re=10,000) regimes. Overall, the proposed method provides fast and reasonably accurate predictions of lift and moment coefficients, particularly in comparison to strip theory, which is commonly used for problems involving arbitrary kinematics

The rate of cosmic ray showers at large zenith angles: a step towards the detection of ultra-high energy neutrinos by the Pierre Auger Observatory

It is anticipated that the Pierre Auger Observatory can be used to detect cosmic neutrinos of >10^19 eV that arrive at very large zenith angles. However showers created by neutrino interactions close to the detector must be picked out against a background of similar events initiated by cosmic ray nuclei. As a step towards understanding this background, we have made the first detailed analysis of air showers recorded at Haverah Park (an array which used similar detectors to those planned for the Auger Observatory) with zenith angles above 60 degs. We find that the differential shower rate from 60 degs to 80 degs. can be predicted accurately when we adopt the known primary energy spectrum above 10^17 eV and assume the QGSJET model and proton primaries. Details of the calculation are given.Comment: 22 pages, 12 figures, to appear in Astroparticle Physic

Quantum Chaos in Open versus Closed Quantum Dots: Signatures of Interacting Particles

This paper reviews recent studies of mesoscopic fluctuations in transport through ballistic quantum dots, emphasizing differences between conduction through open dots and tunneling through nearly isolated dots. Both the open dots and the tunnel-contacted dots show random, repeatable conductance fluctuations with universal statistical proper-ties that are accurately characterized by a variety of theoretical models including random matrix theory, semiclassical methods and nonlinear sigma model calculations. We apply these results in open dots to extract the dephasing rate of electrons within the dot. In the tunneling regime, electron interaction dominates transport since the tunneling of a single electron onto a small dot may be sufficiently energetically costly (due to the small capacitance) that conduction is suppressed altogether. How interactions combine with quantum interference are best seen in this regime.Comment: 15 pages, 11 figures, PDF 2.1 format, to appear in "Chaos, Solitons & Fractals

szinmü 4 felvonásban - írta Victorien Sardou - fordították Fai J. Béla és Makó Lajos - rendező Bihari

Vigszinház Debreczen, 1919 julius 25-én pénteken. Előadás kezdete 7 1/2 órakor.Debreceni Egyetem Egyetemi és Nemzeti Könyvtá

Comparison of Three CIDR Based Fixed-time AI Protocols for Beef Heifers

Several effective fixed-time AI (FTAI) protocols have been developed to facilitate AI while eliminating the need for estrus detection. Among these are the 5-d CO-Synch+CIDR (5d), PG 6-d CIDR (PG-CIDR), and 14-d CIDR-PG (CIDR-PG) protocols. While each of these protocols varies in duration and approach to synchronizing estrus and ovulation, each has been reported as an effective method to facilitate FTAI in beef heifers. Therefore, the objective of this study was to compare FTAI pregnancy rates in beef heifers synchronized with these three CIDR based protocols. Virgin beef heifers (n = 801) at four locations were synchronized with one of three protocols: 1) (5-day CO-Synch + CIDR) an injection of GnRH (100 μg; i.m.) and insertion of a CIDR on d -5, PG (25 mg; i.m.) and CIDR removal on d 0 with a second injection of PG (\u3e4 h after CIDR removal) on d 0 and FTAI at 72 h after CIDR removal, 2) (PG 6-day CIDR) PG (25 mg; i.m.) on d -9, GnRH (100 μg; i.m.) and insertion of a CIDR on d -6, PG and CIDR removal on d 0, and FTAI at 66 h after CIDR removal, or 3) (14-day CIDR-PG) a 14-day CIDR insert from d -30 to -16, PG (25 mg; i.m.) on d 0, and FTAI at 66 h after PG. All heifers received an injection of GnRH (100 μg; i.m.) concurrent with FTAI. Timing of treatment initiation was offset to allow all heifers to receive FTAI concomitantly and at random. Pregnancy success was determined between 35 and 40 d after FTAI by transrectal ultrasonography. Blood samples were collected approximately 12 d before the beginning of each protocol and at the initiation of each protocol to determine estrous cycling status (77%). Data were analyzed using the GLIMMIX procedures of SAS. Fixed-time AI pregnancy success did not differ between treatments (P = 0.13; 62.5%, 56.9%, and 53.3%, for 5-day CO-Synch + CIDR, PG 6-day CIDR, and 14-day CIDR-PG; respectively) or location (P = 0.16; 51.5%, 62.7%, 56.1%, and 58.6% for location 1, 2, 3, and 4; respectively). However, heifers that had reached puberty by initiation of synchronization had greater (P \u3c 0.01) pregnancy success compared to heifers that were prepubertal (60.7% and 47.3%; respectively). In summary, all three protocols had similar FTAI pregnancy success, and puberty status had the greatest impact on pregnancy success

Directionally supervised cellular automaton for the initial peopling of Sahul

Reconstructing the patterns of Homo sapiens expansion out of Africa and across the globe has been advanced using demographic and travel-cost models. However, modelled routes are ipso facto influenced by migration rates, and vice versa. We combined movement ‘superhighways’ with a demographic cellular automaton to predict one of the world’s earliest peopling events — Sahul between 75,000–50,000 years ago. Novel outcomes from the superhighways weighted model include (i) an approximate doubling of the predicted time to continental saturation (~ 10,000 years) compared to that based on the directionally unsupervised model (~5,000 years), suggesting that rates of migration need to account for topographical constraints in addition to rate of saturation; (ii) a previously undetected movement corridor south through the centre of Sahul early in the expansion wave based on the scenarios assuming two dominant entry points into Sahul; and (iii) a better fit to the spatially de-biased, Signor-Lipps corrected layer of initial arrival inferred from dated archaeological material. Our combined model infrastructure provides a data-driven means to examine how people initially moved through, settled, and abandoned different regions of the globe