نتایج جستجو برای: sieve
تعداد نتایج: 4647 فیلتر نتایج به سال:
According to an established concept, injury of the phloem triggers local sieve plate occlusion including callose-mediated constriction and, possibly, protein plugging of the sieve pores. Sieve plate occlusion can also be achieved by distant stimuli, depends on the passage of electropotential waves (EPWs), and is reversible in intact plants. The time-course of the wound response was studied in s...
Asymptotically, the best known algorithms for solving the Shortest Vector Problem (SVP) in a lattice of dimension n are sieve algorithms, which have heuristic complexity estimates ranging from (4/3) down to (3/2) when Locality Sensitive Hashing techniques are used. Sieve algorithms are however outperformed by pruned enumeration algorithms in practice by several orders of magnitude, despite the ...
In this paper, we report efficient implementations of the linear sieve and the cubic sieve methods for computing discrete logarithms over prime fields. We demonstrate through empirical performance measures that for a special class of primes the cubic sieve method runs about two times faster than the linear sieve method even in cases of small prime fields of the size about 150 bits. We also prov...
This paper reviews recent advances in estimation and inference for nonparametric and semiparametric models with endogeneity. It first describes methods of sieves and penalization for estimating unknown functions identified via conditional moment restrictions. Examples include nonparametric instrumental variables regression (NPIV), nonparametric quantile IV regression and many more semi-nonparam...
This paper considers inference on functionals of semi/nonparametric conditional moment restrictions with possibly nonsmooth generalized residuals, which include all of the (nonlinear) nonparametric instrumental variables (IV) as special cases. For these models it is often difficult to verify whether a functional is regular (i.e., root-n estimable) or irregular (i.e., slower than root-n estimabl...
Companion cells represent a major component of the phloem, the plant vascular tissue system responsible for long-distance transport of organic nutrients from the sites of synthesis (source organs) to sites of utilization (sink organs). The companion cells are intimately associated with phloem sieve elements, which make up the actual transport vessel (sieve tube) through which mass flow of assim...
In Codeplay’s Sieve C++, the programmer can place code inside a “sieve block” thereby instructing the compiler to delay writes to global memory and apply them in order on exit from the block. The semantics of sieve blocks makes code more amenable to automatic parallelisation. However, strictly queueing writes until the end of a sieve block incurs overheads and is typically unnecessary. If the p...
Ca2+-binding proteins in the watery saliva of Megoura viciae counteract Ca2+-dependent occlusion of sieve plates in Vicia faba and so prevent the shut-down of food supply in response to stylet penetration. The question arises whether this interaction between aphid saliva and sieve-element proteins is a universal phenomenon as inferred by the coincidence between sieve-tube occlusion and salivati...
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