202 research outputs found
QuickHeapsort: Modifications and improved analysis
We present a new analysis for QuickHeapsort splitting it into the analysis of
the partition-phases and the analysis of the heap-phases. This enables us to
consider samples of non-constant size for the pivot selection and leads to
better theoretical bounds for the algorithm. Furthermore we introduce some
modifications of QuickHeapsort, both in-place and using n extra bits. We show
that on every input the expected number of comparisons is n lg n - 0.03n + o(n)
(in-place) respectively n lg n -0.997 n+ o (n). Both estimates improve the
previously known best results. (It is conjectured in Wegener93 that the
in-place algorithm Bottom-Up-Heapsort uses at most n lg n + 0.4 n on average
and for Weak-Heapsort which uses n extra-bits the average number of comparisons
is at most n lg n -0.42n in EdelkampS02.) Moreover, our non-in-place variant
can even compete with index based Heapsort variants (e.g. Rank-Heapsort in
WangW07) and Relaxed-Weak-Heapsort (n lg n -0.9 n+ o (n) comparisons in the
worst case) for which no O(n)-bound on the number of extra bits is known
Development of "Boni-Protect" - a yeast preparation for use in the control of postharvest diseases of apples
Postharvest pathogens cause major losses in apple production. Gloeosporium album (Pezicula alba) and Gloeosporium perennans (Pezicula malicorticis) are the main pathogens in organic fruit growing. There are several microorganisms with an antagonistic efficency against these fungi. Out of these organisms two yeast isolates have been chosen to develop the plant strengthener Boni-Protect. Boni-Protect reduced the symp-tom development of P. malicorticis, B. cinerea and P. expansum after artificial inoculation of apple wounds. In several field trials preharvest applications of Boni-Protect led to reduced disease development during stor-age
Presence of an expressed 13-tubulin gene (TUBB) in the HLA class I region may provide the genetic basis for HLA-linked microtubule dysfunction
An expressed beta-tubulin gene (TUBB) has previously
been localized to chromosome region 6pter-p21
in man. By using a panel of deletion mutant cell lines and
radiation-reduced hybrids containing fragments of chromosome
6, the TUBB locus could be mapped to the HLA
class I region at 6p21.3. A long range restriction map including
TUBB and several HLA class I genes was then
generated by rotating field gel electrophoresis. The results
show that TUBB maps to a segment 170-370 kb telomeric
of HLA-C. This location suggests that a mutation at the
TUBB locus could be the cause for certain forms of HLAlinked
microtubule dysfunction, including immotile cilia
syndrome
Gene expression of adenosine receptors along the nephron
Gene expression of adenosine receptors along the nephron.BackgroundIn view of the multiple effects of adenosine on kidney function, this study aimed to determine the expression of adenosine receptors (AR) along the rat and mouse nephron.MethodsFor this purpose, we semiquantified mRNA abundance for adenosine A1-, A2A-, A2B-, and A3 receptors by RNAse protection and by reverse transcription-polymerase chain reaction (RT-PCR) in the kidney zones and in the different nephron segments of mice and rats.ResultsWe found very similar expression patterns for rat and mice. For the kidney zones A1-AR mRNA and A2A-AR mRNA abundance displayed a marked difference, with an increase from cortex to the inner medulla. This was not seen for A2B receptors, which showed in general a rather weak expression. Along the nephron, A1-AR was strongly expressed in the thin limbs of Henle and in the collecting duct system and to a lesser extent in the medullary thick ascending limb. A2A-AR mRNA was clearly detected in glomeruli but not in other nephron segments. A2B-AR mRNA was strongly expressed in the cortical thick ascending limb of Henle and in the distal convoluted tubule. A3-AR mRNA was not found in any nephron segment.ConclusionOur data demonstrate a distinct mutual expression of the AR subtypes along the nephron. A1 receptors are expressed in medullary tubular structures, while A2B receptors are predominant in cortical tubular structures. A2A receptor expression in the kidney appears to be restricted to vascular cells
Dynamic Stall Investigation on a Rotating semi-elastic Double-swept Rotor Blade at the Rotor Test Facility Gottingen
Experimental investigations of three-dimensional dynamic stall on a four-bladed Mach-scaled semi-elastic rotor with an innovative double-swept rotor blade planform are presented. The study focuses on the coupling between the aeroelastic behavior of the blade and the underlying aerodynamics. Blade bending moment and flap displacement measurements were conducted using strain gauges and optical tracking of blade tip markers. The aerodynamic behavior was characterized by means of unsteady surface pressure measurements using unsteady pressure-sensitive paint (iPSP) across the outer 65 % of the blade span and fast response pressure transducers at discrete locations. Different cyclicpitch settings were investigated at a rotation frequency of frotor = 23.6 Hz, that corresponds to blade tip Mach and Reynolds numbers of Mtip = 0.282 - 0.285 and Retip = 5.84 - 5.95 x 105. The findings reveal a detailed insight into the non-linear behavior in the flap movement during downstroke. iPSP and pressure transducer data indicates that this non-linear flap behavior is caused by a radially phase-shifted dynamic stall process at the forward and backward swept part of the blade
Complex networks embedded in space: Dimension and scaling relations between mass, topological distance and Euclidean distance
Many real networks are embedded in space, where in some of them the links
length decay as a power law distribution with distance. Indications that such
systems can be characterized by the concept of dimension were found recently.
Here, we present further support for this claim, based on extensive numerical
simulations for model networks embedded on lattices of dimensions and
.
We evaluate the dimension from the power law scaling of (a) the mass of
the network with the Euclidean radius and (b) the probability of return to
the origin with the distance travelled by the random walker. Both
approaches yield the same dimension. For networks with , is
infinity, while for , obtains the value of the embedding
dimension . In the intermediate regime of interest , our numerical results suggest that decreases continously from to , with for close to
. Finally, we discuss the scaling of the mass and the Euclidean
distance with the topological distance . Our results suggest that in
the intermediate regime , and do
not increase with as a power law but with a stretched exponential,
and , where . The parameters
and are related to by , such that . For , increases exponentially with , as
known for , while is constant and independent of . For
, we find power law scaling, and
, with .Comment: 17 pages, 11 figure
Critical dimensions for random walks on random-walk chains
The probability distribution of random walks on linear structures generated
by random walks in -dimensional space, , is analytically studied
for the case . It is shown to obey the scaling form
, where is
the density of the chain. Expanding in powers of , we find that
there exists an infinite hierarchy of critical dimensions, ,
each one characterized by a logarithmic correction in . Namely, for
, ; for ,
; for , ; for , ; for , , {\it etc.\/} In particular, for
, this implies that the temporal dependence of the probability density of
being close to the origin .Comment: LATeX, 10 pages, no figures submitted for publication in PR
Inpatient or day clinic treatment? Results of a multi-site-study
Objective: This naturalistic study aimed to identify criteria which are of relevance for making a decision as to whether inpatient or day hospital treatment is indicated
Unsteady Boundary-Layer Transition Measurements and Computations on a Rotating Blade under Cyclic Pitch Conditions
The presented work tackles the lack of experimental investigations of unsteady laminar-turbulent boundary-layer transition on rotor blades at cyclic pitch actuation, which are important for accurate performance predictions of helicopters in forward flight. Unsteady transition positions were measured on the blade suction side of a four-bladed subscale rotor by means of non-intrusive differential infrared thermography (DIT). Experiments were conducted at different rotation rates corresponding to Mach and Reynolds numbers at 75% rotor radius of up to M_75=0.21 and Re_75 =3.3×10^5 and with varying cyclic blade pitch settings. The setup allowed transition to be measured across the outer 54% of the rotor radius. For comparison, transition was also measured using conventional infrared thermography for steady cases with collective pitch settings only. The study is complemented by numerical simulations including boundary-layer transition modeling based on semi-empirical criteria. DIT results reveal the upstream and downstream motion of boundary-layer transition during upstroke and downstroke, a reasonable comparison to experimental results obtained using the already established sigma*c_p method, and noticeable agreement with numerical simulations. The result is the first systematic study of unsteady boundary-layer transition on a rotor suction side by means of DIT including a comparison to numerical computations
Dynamic-stall measurements using time-resolved pressure-sensitive paint on double-swept rotor blades
The study presents an optimized pressure-sensitive paint (PSP) measurement system that was applied to investigate unsteady surface pressures on recently developed double-swept rotor blades in the rotor test facility at the German Aerospace Center (DLR) in Göttingen. The measurement system featured an improved version of a double-shutter camera that was designed to reduce image blur in PSP measurements on fast rotating blades. It also comprised DLR's PSP sensor, developed to capture transient flow phenomena (iPSP). Unsteady surface pressures were acquired across the outer 65% of the rotor blade with iPSP and at several radial blade sections by fast-response pressure transducers at blade-tip Mach and Reynolds numbers of M_{tip} = 0.282 - 0.285 and Re_{tip}= 5.84 - 5.95 * 10^5. The unique experimental setup allowed for scanning surface pressures across the entire pitch cycle at a phase resolution of 0.225 deg azimuth for different collective and cyclic-pitch settings. Experimental results of both investigated cyclic-pitch settings are compared in detail to a delayed detached eddy simulation using the flow solver FLOWer and to flow visualizations from unsteady Reynolds-averaged Navier Stokes (URANS) computations with DLR's TAU code. The findings reveal a detailed and yet unseen insight into the pressure footprint of double-swept rotor blades undergoing dynamic stall and allow for deducing "stall maps", where confined areas of stalled flow on the blade are identifiable as a function of the pitch phase
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