Strong LL Research Articles

Behavior of fractional quantum Hall states in LLL and 1LL with in-plane magnetic field and Landau level mixing: A numerical investigation**Project supported by the National Natural Science Foundation of China (Grant Nos. 11674041 and 91630205) and Chongqing Research Program for Basic Research and Frontier Technology (Grant No. cstc2017jcyjAX0084).

By exactly solving the effective two-body interaction for a two-dimensional electron system with layer thickness and an in-plane magnetic field, we recently found that the effective interaction can be described by the generalized pseudopotentials (PPs) without the rotational symmetry. With this pseudopotential description, we numerically investigate the behavior of the fractional quantum Hall (FQH) states both in the lowest Landau level (LLL) and first excited Landau level (1LL). The enhancements of the 7/3 FQH state on the 1LL for a small tilted magnetic field are observed when layer thickness is larger than some critical values, while the gap of the 1/3 state in the LLL monotonically reduced with increasing the in-plane field. From the static structure factor calculation, we find that the systems are strongly anisotropic and finally enter into a stripe phase with a large tilting. With considering the Landau level mixing correction on the two-body interaction, we find the strong LL mixing cancels the enhancements of the FQH states in the 1LL.

Top-Down Parsing of Conjunctive Languages

This paper generalizes the notion of a strong LL(k) context-free grammar for the case of conjunctive grammars and develops a top-down parsing algorithm for the resulting language family. A top-down parser of a conjunctive language attempts to construct a derivation of the input string, at each step using a finite lookahead to determine which grammar rule to apply. Fragments of formulae that form the derivation are stored in a tree-structured pushdown. Two ways to implement top-down parsers are suggested: a table-driven parser with a tree-structured pushdown and a recursive descent parser. Both techniques naturally extend their context-free counterparts.

Low level wind shear over Bomba airport

Significant climatological features based on 329 Low Level Wind Shear (LLWS) reports from 1985 to 1989 at Bombay airport are presented, The monsoon season has the highest frequency of occurrence of LLWS mainly due to thunderstorms and strong gusty winds, Other than monsoon season, occurrence of LLWS is related to sea and land breeze and nocturnal increase of surface temperature during night. The preferred time of occurrence of LLWS is between 0000 to 0600 IST and 1800 to 240J IST. The simultaneous occurrence of strong and severe LL WS, low cloud ceiling and very poor visibility has an adverse effect on aircraft operations at Bombay airport during landing and take-off.

An improvement to immediate error detection in strong LL(1) parsers

An improvement to immediate error detection in strong LL(1) parsers

Endogenous circadian rhythms in rats recovered from lateral hypothalamic lesions

Compared with intact controls, rats which have recovered spontaneous ingestion after lateral hypothalamic lesions show exaggerated nocturnal rhythms. Food intake was low and water intake negligible in the light part of a LD 12:12 cycle. The endogenous rhythms persisted in constant dark, and were clearly free running in constant light with periods of 25–26 hr. Animals with relatively asymmetric damage showed strong LL suppression of intake on the first day; animals with symmetric damage showed no LL suppression and the strongest free running rhythms; rats with the largest lesions showed a permanent LL suppression of fluid intake from Day 3 onward. The LL rhythms were rapidly reentrained with a restored LD cycle, with phase shifts of over 90°/24 hr. Recovered laterals which were previously blinded by orbital enucleation showed free running rhythms with periods close to 24 hr. The division of the 24 hr period into active (α) and quiescent (ϱ) phases is much more sharply defined after the lesion. This is especially marked for drinking; feeding and activity rhythms are very similar. It is suggested that the recovered lateral is dependent upon endogenous oscillator(s) subserving motivated behaviors, and implications for the recovery of function and residual impairments are discussed.

On the complexity of LR(k) testing

The problem of determining whether an arbitrary context-free grammar is a member of some easily parsed subclass of grammars such as the LR(k) grammars is considered. The time complexity of this problem is analyzed both when k is considered to be a fixed integer and when k is considered to be a parameter of the test. In the first case, it is shown that for every k there exists an O(n k+2 ) algorithm for testing the LR(k) property, where n is the size of the grammar in question. On the other hand, if both k and the subject grammar are problem parameters, then the complexity of the problem depends very strongly on the representation chosen for k. More specifically, it is shown that this problem is NP-complete when k is expressed in unary. When k is expressed in binary the problem is complete for nondeterministic exponential time. These results carry over to many other parameterized classes of grammars, such as the LL(k), strong LL(k), SLR(k), LC(k), and strong LC(k) grammars.