Status and Management of Pyrethroid Resistance in the Predatory Mite, \u3ci\u3eAmblyseius Fallacis\u3c/i\u3e (Acarina: Phytoseiidae)

Low levels of (5-15 fold) resistance to synthetic pyrethroid (SP) insecticides occur in unexposed apple orchard populations of the predatory mite, Amblyseius fallacis Garman. Permethrin resistance in one strain has been elevated 60--500 fold by selections in green- houses. Multiple resistances to DDT and azinphosmethyl are present and cross-resistance to SP-related compounds is generic at 10--250 fold. Permethrin resistance appears due to both hydrolytic esterase and knock down resistance mechanisms. Permethrin resistance appears to be polygenic and more recessive than dominant; it is unstable in the presence of high densities of susceptible immigrant types, but is reasonably stable in the presence of unselected, resistant immigrant types. Successful establishment of SP-resistant mites into SP-treated, commercial apple orchards was monitored using electrophoretic finger-printing techniques over a two year period. Aspects of management of resistance in A. fallacis to improve IPM are discussed

The Potential of Learned Index Structures for Index Compression

Inverted indexes are vital in providing fast key-word-based search. For every term in the document collection, a list of identifiers of documents in which the term appears is stored, along with auxiliary information such as term frequency, and position offsets. While very effective, inverted indexes have large memory requirements for web-sized collections. Recently, the concept of learned index structures was introduced, where machine learned models replace common index structures such as B-tree-indexes, hash-indexes, and bloom-filters. These learned index structures require less memory, and can be computationally much faster than their traditional counterparts. In this paper, we consider whether such models may be applied to conjunctive Boolean querying. First, we investigate how a learned model can replace document postings of an inverted index, and then evaluate the compromises such an approach might have. Second, we evaluate the potential gains that can be achieved in terms of memory requirements. Our work shows that learned models have great potential in inverted indexing, and this direction seems to be a promising area for future research.Comment: Will appear in the proceedings of ADCS'1

Russian-to-English Homographs

Most dictionaries define homograph in terms of words taken from the same language, saying nothing about words from two different languages involving partially overlapping alphabets (e.g., the English Latin alphabet and the Russian Cyrillic alphabet). For example, in their Dictionary or Linguistics (Littlefield and Adams, 1969), Mario Pei and Frank Gaynor define homograph as a word identical in written form with another given word of the same language, but entirely different in origin, sound, and meaning . In contrast, this paper, in considered conformance with the etymology of the word from the Greek, defines an interlingual homograph to be one of two or more words which are identically written regardless of their meanings, derivation, pronunciation, language membership or alphabet constituency

The Goal of Classroom Instruction: Entertainment or Learning

Using nearly 10,000 college students, this study isolated six factors of an instructor\u27s behavior which influence how much students learn and whether they would take another course from the instructor. The results provide suggestions for improving your instruction

Using Perturbative Least Action to Recover Cosmological Initial Conditions

We introduce a new method for generating initial conditions consistent with highly nonlinear observations of density and velocity fields. Using a variant of the Least Action method, called Perturbative Least Action (PLA), we show that it is possible to generate several different sets of initial conditions, each of which will satisfy a set of highly nonlinear observational constraints at the present day. We then discuss a code written to test and apply this method and present the results of several simulations.Comment: 24 pages, 6 postscript figures. Accepted for publication in Astrophysical Journa

Ionizing radiation fluctuations and large-scale structure in the Lyman-alpha forest

We investigate the large-scale inhomogeneities of the hydrogen ionizing radiation field in the Universe at redshift z=3. Using a raytracing algorithm, we simulate a model in which quasars are the dominant sources of radiation. We make use of large scale N-body simulations of a LambdaCDM universe, and include such effects as finite quasar lifetimes and output on the lightcone, which affects the shape of quasar light echoes. We create Lya forest spectra that would be generated in the presence of such a fluctuating radiation field, finding that the power spectrum of the Lya forest can be suppressed by as much as 15 % for modes with k=0.05-1 Mpc/h. This relatively small effect may have consequences for high precision measurements of the Lya power spectrum on larger scales than have yet been published. We also investigate another radiation field probe, the cross-correlation of quasar positions and the Lya forest. For both quasar lifetimes which we simulate (10^7 yr and 10^8 yr), we expect to see a strong decrease in the Lya absorption close to other quasars (the ``foreground'' proximity effect). We then use data from the Sloan Digital Sky Survey First Data Release to make an observational determination of this statistic. We find no sign of our predicted lack of absorption, but instead increased absorption close to quasars. If the bursts of radiation from quasars last on average < 10^6 yr, then we would not expect to be able to see the foreground effect. However, the strength of the absorption itself seems to be indicative of rare objects, and hence much longer total times of emission per quasar. Variability of quasars in bursts with timescales > 10^4yr and < 10^6 yr could reconcile these two facts.Comment: Submitted to ApJ, 21 pages, 17 postscript figures, emulateapj.st

Phytoseiid mites associated with spider mites on hops in the Willamette Valley, Oregon

Densities and damage by twospotted spider mites, Tetranychus urticae Koch and levels of phytoseiid mites on hops were assessed in 34 commercial fields and at 11-19 sites of escaped hops in the Willamette valley of western Oregon in 1991-1992. Amblyseius fallacis (Garman), Typhlodromus pyri Scheuten, Amblyseius andersoni Chant and Metaseiulus occidentalis (Nesbitt) were most common. On escaped hops, T. pyri was more common than other phytoseiids. It occurred widely on plants surrounding commercial hops including blackberry and other rosaceous plants and probably is a vagrant on escaped hops. A. fallacis was most common in commercial hops making up 88% of all specimens, followed by many fewer M. occidentalis and T. pyri. Early spring survival of A Jallacis in commercial hops was poor because of certain cultural practices used in the spring. Means to improve biological control of spider mites on hops are discussed including amended methods of hop culture, use of selective pesticides and inoculative releases of predaceous mites.Keywords: Amblyseiusfallacis; Metaseiulus occidentalis; Typhlodromus pyri; Amblyseius andersoni; Tetranychus urtica