3,165 research outputs found
Attraction of Apple Maggot Flies (Diptera: Tephritidae) to Synthetic Fruit Volatile Compounds and Food Attractants in Michigan Apple Orchards
The apple maggot, Rhagoletis pomonella (Walsh), is a serious pest of apples in the United States, requiring reliable monitoring and control programs. Various synthetic apple volatile lures with and without protein hydrolysate, ammonium acetate, or ammonium carbonate were evaluated from 1998-2000 for their attractiveness to R. pomonella adults with red sticky-sphere (9 cm diam.) monitoring traps. A blend consisting of butyl butanoate (10%), propyl hexano- ate (4%), butyl hexanoate (37%), hexyl butanoate (44%), and pentyl hexanoate (5%) was the most effective lure tested for attracting both sexes of R. pomonella adults during all three field seasons. The addition of protein hydrolysate or ammonium compounds to spheres baited with a commercial attractant (BioLure) consisting of plastic dispensers containing butyl hexanoate, did not significantly increase apple maggot fly captures. Spheres baited with the blend or with butyl hexanoate in polyethylene vials and spheres baited with BioLure dispensers were highly selective in capturing R. pomonella flies relative to non-target insects. However, spheres baited with ammonium compounds with or without synthetic apple lures were non-selective with respect to apple maggot captures. Protein hydrolysate alone was ineffective for monitoring R. pomonella flies. We provide further evidence that baiting red-sticky sphere traps with the volatile blend without ammonium bait additives creates a highly effective and selective device for capturing apple maggot flies. The blend could be an important addition to current monitoring and control programs for apple maggot flies in Michigan orchards and other important apple growing regions
El sistema de cierre asistido al vacío en el tratamiento del pie diabético avanzado
Deep diabetic foot lesions pose an enormous therapeutic problem.
The purpose of this study was to present the experience of the use of vacuum
assisted closure (VAC) in the treatment of advanced and complicated diabetic foot
lesions. MATERIAL AND METHODS: Five cases of advanced diabetic foot that were
treated with VAC were prospectively studied. Three patients were diagnosed with
renal failure, including one with renal transplant, who were receiving
immunosuppression therapy. Four patients had undergone local foot surgery. The
foot lesions were classified as grade 3 or 4 according to the Wagner
classification. In all patients extensive debridement was performed that resulted
in open minor amputations in four cases and resection of the metatarsophalangeal
joint in one case. The VAC was applied during the same procedure. The median
follow-up period of the patients was 9 months. RESULTS: Foot salvage was achieved
in all cases. The median number of changes of VAC was 16 within median period of
8 weeks. Half of the changes were performed as an outpatient procedure. There
were no major complications or clinical signs of infection observed. In one case
before treatment with VAC began, angioplasty of the iliac artery and superficial
femoral artery was performed. Other interventions carried out after the treatment
was started were, two distal revascularizations and two partial transmetatarsal
amputations. CONCLUSIONS: VAC appears to be very useful in the treatment of
advanced diabetic foot lesion
Computable Bayesian Compression for Uniformly Discretizable Statistical Models
Supplementing Vovk and V'yugin's `if' statement, we show that
Bayesian compression provides the best enumerable compression for
parameter-typical data if and only if the parameter is Martin-L\"of
random with respect to the prior. The result is derived for
uniformly discretizable statistical models, introduced here. They
feature the crucial property that given a~discretized parameter, we
can compute how much data is needed to learn its value with little
uncertainty. Exponential families and certain nonparametric models
are shown to be uniformly discretizable
A general definition of conditional information and its application to ergodic decomposition
We discuss a simple definition of conditional mutual
information (CMI) for fields and -fields. The new
definition is applicable also in nonregular cases, unlike the
well-known but more restricted definition of CMI by
Dobrushin. Certain properties of the two notions of CMI and their
equivalence for countably generated -fields are
established. We also consider an application, which concerns the
ergodic decomposition of mutual information for stationary
processes. In this case, CMI is tightly linked, via additivity of
information, with entropy defined as self-information. Thus we
reconsider the latter concept in some detail
A general definition of conditional information and its application to ergodic decomposition
We discuss a~simple definition of conditional mutual
information (CMI) for fields and -fields. The new definition
is applicable also in nonregular cases, unlike the well-known but
more restricted definition of CMI by Dobrushin. Certain properties
of the two notions of CMI and their equivalence for countably
generated -fields are established. We also consider an
application, which concerns the ergodic decomposition of
mutual information for stationary processes. In this case, CMI is
tightly linked, via additivity of information, with entropy defined
as self-information. Thus we reconsider the latter concept in some
detail
On the Vocabulary of Grammar-Based Codes and the Logical Consistency of Texts
The article presents a new interpretation for Zipf's law in
natural language which relies on two areas of information
theory. We reformulate the problem of grammar-based compression
and investigate properties of strongly nonergodic stationary
processes. The motivation for the joint discussion is to prove a
proposition with a simple informal statement: If an -letter
long text describes independent facts in a random but
consistent way then the text contains at least
different words.
In the formal statement, two specific postulates are
adopted. Firstly, the words are understood as the nonterminal
symbols of the shortest grammar-based encoding of the
text. Secondly, the texts are assumed to be emitted by a
nonergodic source, with the described facts being binary IID
variables that are asymptotically predictable in a
shift-invariant way.
The proof of the formal proposition applies several new tools.
These are: a construction of universal grammar-based codes for
which the differences of code lengths can be bounded easily,
ergodic decomposition theorems for mutual information between the
past and future of a stationary process, and a lemma that bounds
differences of a sublinear function.
The linguistic relevance of presented modeling assumptions,
theorems, definitions, and examples is discussed in
parallel.While searching for concrete processes to which our
proposition can be applied, we introduce several instances of
strongly nonergodic processes. In particular, we define the
subclass of accessible description processes, which formalizes
the notion of texts that describe facts in a self-contained way
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Evaluation of semiochemical based push-pull strategy for population suppression of ambrosia beetle vectors of laurel wilt disease in avocado.
Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae and Platypodinae) bore into tree xylem to complete their life cycle, feeding on symbiotic fungi. Ambrosia beetles are a threat to avocado where they have been found to vector a symbiotic fungus, Raffaelea lauricola, the causal agent of the laurel wilt disease. We assessed the repellency of methyl salicylate and verbenone to two putative laurel wilt vectors in avocado, Xyleborus volvulus (Fabricius) and Xyleborus bispinatus (Eichhoff), under laboratory conditions. Then, we tested the same two chemicals released from SPLAT flowable matrix with and without low-dose ethanol dispensers for manipulation of ambrosia beetle populations occurring in commercial avocado. The potential active space of repellents was assessed by quantifying beetle catch on traps placed 'close' (~5-10 cm) and 'far' (~1-1.5 m) away from repellent dispensers. Ambrosia beetles collected on traps associated with all in-field treatments were identified to species to assess beetle diversity and community variation. Xyleborus volvulus was not repelled by methyl salicylate (MeSA) or verbenone in laboratory assays, while X. bispinatus was repelled by MeSA but not verbenone. Ambrosia beetle trap catches were reduced in the field more when plots were treated with verbenone dispensers (SPLAT) co-deployed with low-dose ethanol dispensers than when treated with verbenone alone. Beetle diversity was highest on traps deployed with low-dose ethanol lures. The repellent treatments and ethanol lures significantly altered the species composition of beetles captured in experiment plots. Our results indicate that verbenone co-deployed with ethanol lures holds potential for manipulating ambrosia beetle vectors via push-pull management in avocado. This tactic could discourage immigration and/or population establishment of ambrosia beetles in commercial avocado and function as an additional tool for management programs of laurel wilt
Optimal Hedging with the Vector Autoregressive Model
__Abstract__
We derive the optimal hedging ratios for a portfolio of assets driven by a Cointegrated Vector Autoregressive model with general cointegration rank. Our hedge is optimal in the sense of minimum variance portfolio.
We consider a model that allows for the hedges to be cointegrated with the hedged asset and among themselves. We nd that the minimum variance hedge for assets driven by the CVAR, depends strongly on the portfolio holding period. The hedge is dened as a function of correlation and cointegration parameters. For short holding periods the correlation impact is predominant. For long horizons, the hedge ratio should overweight the cointegration parameters rather then short-run correlation information. In the innite horizon, the hedge ratios shall be equal to the cointegrating vector. The hedge ratios for any intermediate portfolio holding period should be based on the weighted average of correlation and cointegration parameters.
The results are general and can be applied for any portfolio of assets that can be modeled by the CVAR of any rank and order
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