10,750 research outputs found
Market Timing and Selectivity: Evidence from Australian Equity Superannuation Funds
In this performance evaluation study, two questions are addressed. First, do active fund managers possess macro and micro forecasting skills that deliver superior risk-adjusted returns? Second, what is the nature of market timing/stock selectivity trade off in the generation of alpha? The answers from this study are as follows: as an industry, managers delivered inferior returns for superannuation investors for the period 1991 through 1999. The study provides little evidence that the Australian funds management industry holds sufficient macro and/or micro forecasting abilities to generate positive alpha. While previous research has found that inferior market timing decisions are compensated for by superior stock selection skills, this study finds no substantive inverse relationship between timing and selectivity.Performance evaluation; Timing; Selectivity.
A Genetic Locus Regulates the Expression of Tissue-Specific mRNAs from Multiple Transcription Units
129 GIX- mice, unlike animals of the congeneic partner strain GIX+, do not express significant amounts of the retroviral antigens gp70 and p30. Evidence is presented indicating that the GIX phenotype is specified by a distinct regulatory gene acting on multiple transcription units to control the levels of accumulation of specific mRNA species. The steady-state levels of retroviral-homologous mRNA from the tissues of GIX+ and GIX- mice were examined by blot hybridization using as probes DNA fragments from cloned murine leukemia viruses. RNA potentially encoding viral antigens was reduced or absent in GIX- mice, even though no differences in integrated viral genomes were detected between these congeneic strains by DNA blotting. Tissue-specific patterns of accumulation of these RNA species were detected in brain, epididymis, liver, spleen, and thymus, and several distinct RNA species were found to be coordinately regulated with the GIX phenotype. Measurements of RNA synthesis suggest a major role for transcriptional control in the regulation of some retroviral messages
A Split-Stem Lesion on Young Hybrid \u3ci\u3ePopulus\u3c/i\u3e Trees Caused by the Tarnished Plant Bug, \u3ci\u3eLygus Lineolaris\u3c/i\u3e (Hemiptera: [Heteroptera]: Miridae)
The tarnished plant bug, known principally as an agricultural pest, injures young hybrid Populus by feeding on the stems and meristems. Tarnished plant bug eggs, fungi associated with some lesions, and simple mechanical stimuli alone from feeding appeared not to cause lesion formation. Of 20 Populus hybrids tested in a clonal trial, four appeared to be consistently susceptible to lesion injury, with Populus nigra var. betulifolia x trichocarpa the most susceptible. Several clones showed high resistance in the trial but a few were susceptible in other plantings and in host preference tests when caged with tarnished plant bugs. Lesions diminished tenfold on Populus where horseweed, the insect\u27s principal wild host, grew along with susceptible poplars. The tarnished plant bug can be suppressed by ultra-low volume pesticides and cultural manipulation of understory vegetation
Correspondence between sound propagation in discrete and continuous random media with application to forest acoustics
Although sound propagation in a forest is important in several applications, there are currently no rigorous yet computationally tractable prediction methods. Due to the complexity of sound scattering in a forest, it is natural to formulate the problem stochastically. In this paper, it is demonstrated that the equations for the statistical moments of the sound field propagating in a forest have the same form as those for sound propagation in a turbulent atmosphere if the scattering properties of the two media are expressed in terms of the differential scattering and total cross sections. Using the existing theories for sound propagation in a turbulent atmosphere, this analogy enables the derivation of several results for predicting forest acoustics. In particular, the second-moment parabolic equation is formulated for the spatial correlation function of the sound field propagating above an impedance ground in a forest with micrometeorology. Effective numerical techniques for solving this equation have been developed in atmospheric acoustics. In another example, formulas are obtained that describe the effect of a forest on the interference between the direct and ground-reflected waves. The formulated correspondence between wave propagation in discrete and continuous random media can also be used in other fields of physics
An Online Environmental Approach to Service Interaction Management in Home Automation
Home automation is maturing with the increased deployment of networks and
intelligent devices in the home. Along with new protocols and devices, new
software services will emerge and work together releasing the full potential of
networked consumer devices. Services may include home security, climate control
or entertainment. With such extensive interworking the phenomenon known as
service interaction, or feature interaction, appears. The problem occurs when
services interfere with one another causing unexpected or undesirable outcomes.
The main goal of this work is to detect undesired interactions between devices
and services while allowing positive interactions between services and devices.
If the interaction is negative, the approach should be able to handle it in an
appropriate way.
Being able to carry out interaction detection in the home poses certain challenges.
Firstly, the devices and services are provided by a number of vendors and will
be using a variety of protocols. Secondly, the configuration will not be fixed,
the network will change as devices join and leave. Services may also change and
adapt to user needs and to devices available at runtime. The developed approach
is able to work with such challenges.
Since the goal of the automated home is to make life simpler for the occupant,
the approach should require minimal user intervention.
With the above goals, an approach was developed which tackles the problem.
Whereas previous approaches solving service interaction have focused on the
service, the technique presented here concentrates on the devices and their surrounds,
as some interactions occur through conflicting effects on the environment.
The approach introduces the concept of environmental variables. A variable may
be room temperature, movement or perhaps light. Drawing inspiration from
the Operating Systems domain, locks are used to control access to the devices
and environmental variables. Using this technique, undesirable interactions are
avoided. The inclusion of the environment is a key element of this approach as
many interactions can happen indirectly, through the environment.
Since the configuration of a home’s devices and services is continually changing,
developing an off-line solution is not practical. Therefore, an on-line approach in
the form of an interaction manager has been developed. It is the manager’s role
to detect interactions.
The approach was shown to work successfuly. The manager was able to successfully
detect interactions and prevent negative interactions from occurring.
Interactions were detected at both device and service level. The approach is flexible:
it is protocol independent, services are unaware of the manager, and the
manager can cope with new devices and services joining the network. Further,
there is little user intervention required for the approach to operate
Inference for double Pareto lognormal queues with applications
In this article we describe a method for carrying out Bayesian inference for the double Pareto lognormal (dPlN) distribution which has recently been proposed as a model for heavy-tailed phenomena. We apply our approach to inference for the dPlN/M/1 and M/dPlN/1 queueing systems. These systems cannot be analyzed using standard techniques due to the fact that the dPlN distribution does not posses a Laplace transform in closed form. This difficulty is overcome using some recent approximations for the Laplace transform for the Pareto/M/1 system. Our procedure is illustrated with applications in internet traffic analysis and risk theory.Heavy tails, Bayesian inference, Queueing theory
Role of Peptide Backbone Conformation on Biological Activity of Chemotactic Peptides
To investigate the role of peptide backbone conformation on the biological activity of chemotactic peptides, we synthesized a unique analog of N-formyl-Met-Leu-Phe-OH incorporating the C α,α disubstituted residue, dipropylglycine (Dpg) in place of Leu. The conformation of the stereochemically constrained Dpg analog was examined in the crystalline state by x-ray diffraction and in solution using NMR, IR, and CD methods. The secretagogue activity of the peptide on human neutrophils was determined and compared with that of a stereochemically constrained, folded type II β-turn analog incorporating 1-aminocyclohexanecarboxylic acid (Ac6c) at position 2 (f-Met- Ac6c -Phe-OMe), the parent peptide (f-Met-Leu-Phe-OH) and its methyl ester derivative (f-Met-Leu-Phe-OMe). In the solid state, the Dpg analog adopts an extended β-sheet-like structure with an intramolecular hydrogen bond between the NH and CO groups of the Dpg residue, thereby forming a fully extended (C5) conformation at position 2. The ϕ and ψ values for Met and Phe residues are significantly lower than the values expected for an ideal antiparallel beta conformation causing a twist in the extended backbone both at the N and C termini. Nuclear magnetic resonance studies suggest the presence of a significant population of the peptide molecules in an extended antiparallel β conformation and the involvement of Dpg NH in a C5 intramolecular hydrogen bond in solutions of deuterated chloroform and deuterated dimethyl sulfoxide. IR studies provide evidence for the presence of an intramolecular hydrogen bond in the molecule and the antiparallel extended conformation in chloroform solution. CD spectra in methanol, trifluoroethanol, and trimethyl phosphate indicate that the Dpg peptide shows slight conformational flexibility, whereas the folded Ac6c analog is quite rigid. The extended Dpg peptide consistently shows the highest activity in human peripheral blood neutrophils, being approximately 8 and 16 times more active than the parent peptide and the folded Ac6c analog, respectively. However, the finding that all four peptides have ED50 (the molar concentration of peptide to induce half-maximal enzyme release) values in the 10(-8)-10(-9) M range suggests that an induced fit mechanism may indeed be important in this ligand-receptor interaction. Moreover, it is also possible that alterations in the backbone conformation at the tripeptide level may not significantly alter the side chain topography and/or the accessibility of key functional groups important for interaction with the receptor
Low temperature/short duration steaming as a sustainable method of soil disinfection
This report was presented at the UK Organic Research 2002 Conference. Soil samples containing resting structures of fungal crop pathogens (Verticillium dahliae, Sclerotinia sclerotiorum, Sclerotium cepivorum, Pythium ultimum), potato cyst nematodes (Globodera rostochiensis and Globodera pallida) and weeds (Chenopodium album and Agropyron repens) were treated with aerated steam in the laboratory at temperatures ranging from 50–80oC in a specially constructed apparatus. Steaming at 50 or 60oC for three minutes, followed by an eight-minute resting period in the steamed soil and immediate removal from the soil thereafter, resulted in 100% kill of all weeds, fungi and nematodes. Low temperature/ short duration soil steaming could become a sustainable alternative to chemical or high-temperature steam soil disinfestation
Combined Earth and Rock Bearing Foundation - Hospital Humana Mexico City D.F.
This text describes the design and performance of a shallow spread footing foundation system for a large medical care facility in Mexico City. The project is unusual because the spread footings bear on a combination of basaltic lava and coarse sand fill containing angular lava fragments, the latter of which was densified using the dynamic deep compaction process. In the following narrative, the exploratory program is described, the geotechnical design and construction process is explained, and the inspection procedure for footings bearing on rock and soil is discussed. Further, the results of precise settlement monitoring for the structure are presented
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