Trap Distance Research Articles

Too big to be noticed: cryptic invasion of Asian camel crickets in North American houses.

Despite the rapid expansion of the built environment, we know little about the biology of species living in human-constructed habitats. Camel crickets (Rhaphidophoridae) are commonly observed in North American houses and include a range of native taxa as well as the Asian Diestrammena asynamora (Adelung), a species occasionally reported from houses though considered to be established only in greenhouses. We launched a continental-scale citizen science campaign to better understand the relative distributions and frequency of native and nonnative camel crickets in human homes across North America. Participants contributed survey data about the presence or absence of camel crickets in homes, as well as photographs and specimens of camel crickets allowing us to identify the major genera and/or species in and around houses. Together, these data offer insight into the geographical distribution of camel crickets as a presence in homes, as well as the relative frequency and distribution of native and nonnative camel crickets encountered in houses. In so doing, we show that the exotic Diestrammena asynamora not only has become a common presence in eastern houses, but is found in these environments far more frequently than native camel crickets. Supplemental pitfall trapping along transects in 10 urban yards in Raleigh, NC revealed that D. asynamora can be extremely abundant locally around some homes, with as many as 52 individuals collected from pitfalls in a single yard over two days of sampling. The number of D. asynamora individuals present in a trap was negatively correlated with the trap’s distance from a house, suggesting that these insects may be preferentially associated with houses but also are present outside. In addition, we report the establishment in the northeastern United States of a second exotic species, putatively Diestrammena japanica Blatchley, which was previously undocumented in the literature. Our results offer new insight into the relative frequency and distribution of camel crickets living in human homes, and emphasize the importance of the built environment as habitat for two little-known invading species of Orthoptera.

PECVD and Thermal Gate Oxides on 3C Vs. 4H SiC – Impact on Traps, Leakage and Energy Offsets

Silicon carbide (SiC) is particularly suitable for manufacturing of medium and high power FETs. Two SiC polytypes most commonly used for that purpose, i.e. cubic 3C and hexagonal 4H, differ, however, in many aspects, which influence the operation of the devices. The differences in interface trap distributions, gate leakage and energy band model offsets resulting from the SiC polytypes were investigated in this work. Samples. Characterized were two lots of wafers (3C-SiC and 4H-SiC) fabricated by Acreo AB. The 3C-SiC lot consisted of two n-type (001) 3C-SiC wafers. The substrates from Hoya were covered at Acreo by a n-type epitaxial layer with nitrogen doping of 7×1015 cm-3. One wafer was thermally oxidized in wet oxygen (T = 1150°C, 1h) while the other had the SiO2 layer deposited by PECVD at T = 300°C. This second wafer was further annealed for 3 hours in wet oxygen at T = 950°C. The oxide thickness on both wafers was 60 nm.The 4H-SiC lot consisted of two SiC-4H n-type wafers, one with a thermal (53 nm) and another with a PECVD (45 nm) gate oxide fabricated in the processes analogical to the 3C-SiC lot. Measurements.The gate leakage currents were measured on Agilent B1500AB. The interface trap distributions were measured by standard conductance method on Agilent 4294A. The energy band model offsets were established using our own specialized equipment for photoelectric measurements. The methods used were discussed in details in [1,2,3]. Results. The important difference between the 3C and 4H polytypes is the width of the energy gap: EG(3C)=2.36 eV and EG(4H)=3.23 eV [4]. In Fig. 1 the trap density distributions measured in the samples in both polytypes are presented. The energy axis shows the trap distance from the top of the valence band EV, what enables the comparison of Dit in both systems. As expected, the Dit values in 4H-SiC are higher than those in 3C-SiC, irrespective of the oxide preparation method, due to the presence of a band of interface traps in the oxide, so called NIT (near-interface traps), caused probably by oxygen vacancy defects (O3ΞSiH HSiΞO3) producing trapping states at 3.0 eV...3.2 eV above EV, as reported by Afanas’ev [4] and others [5].An interesting feature can be demonstrated comparing gate leakage currents. In Fig. 2 we present the averaged leakage current density characteristics measured in both polytype samples. One can notice a very small difference in the leakage current density J between the oxides, while the difference with respect to the substrate polytype is very large. The density of leakage currents in 4H is by two orders of magnitude lower than that in 3C. Since the oxide preparation procedure in both samples was identical, the difference could not be explained by the oxide properties only. We presume that the mechanism of the increased leakage in the 3C-SiC is connected with trap enhanced tunneling from the conductance band by the NIT defects.Finally we present the most important 3C- and 4H-SiC MOSC energy-band model offsets shown in Fig. 3. The offset values are given in Tab. 1. All the values were taken for PECVD oxide and Al gate. Conclusions Energy-band model offsets, trap density distributions and gate leakage characteristics of MOS capacitors with PECVD and thermal gate oxide on 3C- and 4H-SiC were compared. The important role of NIT traps in both polytypes influencing different device characteristics was demonstrated.

Efficacy of Pheromone Trapping of the Sweetpotato Weevil (Coleoptera: Brentidae): Based on Dose, Septum Age, Attractive Radius, and Mass Trapping

Pheromone dose, effective trapping distance, and longevity of the rubber septa loaded with sex pheromone of Cylas formicarius (F.) (Coleoptera: Brentidae) were evaluated for their impact on the efficacy of mass trapping of the insect in sweet potato fields in Guam in 2012-2013. The number of adults caught at different distances (10-100 m) was significantly different. Catches declined with increasing release distance from the trap in both downwind and upwind directions. While the maximum radius of attraction of pheromone-baited trap for C. formicarius in the field was 80 m, the effective distance for recapturing marked adults in the pheromone-baited Unitraps was 60 m. Pheromone lures were able to capture adults of C. formicarius after being stored in the laboratory for up to 98 d. The number of catches per trap per week was highest when lures were 0-14- and 15-28-d-old, and longer storage of septa led to a progressive reduction of catches. Pheromone traps baited with 100-μg lures captured significantly more adults compared with those loaded with 10-μg lures. In addition, effectiveness of pheromone trapping on damage to sweet potato was tested at two locations. Number of trapped adults, damage level at different times after trap installation, and yield production were evaluated. The number of C. formicarius adults collected in traps at both locations fluctuated dramatically among sampling dates and peaked on 13 September 2013, after which time the number of captures noticeably declined. This decrease was correlated to the increasing age and depletion of the pheromone lures. Pheromone traps significantly reduced feeding damage caused by weevils (<1 feeding hole per root in treatment; up to 38 feeding holes per root in the control) at both locations. Being consistent with damage levels, sweet potato yields in fields with traps were higher than those in untreated controls. We conclude that pheromone-baited traps are effective in reducing damage due to C. formicarius.

Mosquito communities with trap height and urban-rural gradient in Adelaide, South Australia: implications for disease vector surveillance.

Understanding the factors influencing mosquito distribution is important for effective surveillance and control of nuisance and disease vector mosquitoes. The goal of this study was to determine how trap height and distance to the city center influenced the abundance and species of mosquitoes collected in Adelaide, South Australia. Mosquito communities were sampled at two heights (<2 m and ~10 m) along an urban-rural gradient. A total of 5,133 mosquitoes was identified over 176 trap nights. Aedes notoscriptus, Ae. vigilax, and Culex molestus were all more abundant in lower traps while Cx. quinquefasciatus (an ornithophilic species) was found to be more abundant in high traps. Distance to city center correlated strongly with the abundance of Ae. vigilax, Ae. camptorhynchus, Cx. globocoxitus, and Cx. molestus, all of which were most common at the sites farthest from the city and closest to the saltmarsh. Overall, the important disease vectors in South Australia (Ae. vigilax, Ae. camptorhynchus, Ae. notoscriptus, and Cx. annulirostris) were more abundant in low traps farthest from the city and closest to the saltmarsh. The current mosquito surveillance practice of setting traps within two meters of the ground is effective for sampling populations of the important disease vector species in South Australia.

Physical origin of surface slip morphologies induced by regular self-organized dislocation patterns in fatigued copper single crystals

In this study, the formation mechanisms of typical dislocation patterns in fatigued copper single crystals were systematically investigated and summarized. The formation of persistent slip band (PSB) ladders depends on the width of extended dislocation and the trap distance of dipole. When the actual capture distance dtrap is less than the critical capture distance dcritical, a group of relatively stable multipoles are obtained from many dipole segments, followed by the formation of the veins and PSB-ladder structures. Further evolution will bring about more and more ladder-like PSBs appearing in one local zone until 100% PSB, which is corresponding to the formation of developing deformation bands (DBs), and then the developing DBs will be converted into the well-developed DBs by merging ladder-like PSBs. After the secondary fatigue, the veins, PSB ladders, or walls can be regarded as the nucleation source of new slip bands (SBs). No matter how the surface slip morphologies change, the evolution of dislocation patterns always keeps the dynamic equilibrium and essentially reflects the constant deepening of strain localization.

Enhanced optoelastic interaction range in liquid crystals with negative dielectric anisotropy

We demonstrate that the long-range interaction between surface-functionalized microparticles immersed a nematic liquid crystal—a “nematic colloid”—and a laser-induced “ghost colloid” can be enhanced by a low-voltage quasistatic electric field when the nematic mesophase has a negative dielectric anisotropy. The optoelastic trapping distance is shown to be enhanced by a factor up to 2.5 in presence of an electric field. Experimental data are quantitatively described with a theoretical model accounting for the spatial overlap between the orientational distortions around the microparticle and those induced by the trapping light beam itself.

Rigid DNA Beams for High‐Resolution Single‐Molecule Mechanics

Rigid DNA Beams for High‐Resolution Single‐Molecule Mechanics

Factors influencing adult male Grapholita molesta dispersal in commercial Malus and Prunus host crops

AbstractThe oriental fruit moth (OFM), Grapholita molesta (Busck) (Lepidoptera: Tortricidae), has been an economic pest of apples (Malus spp.) and peaches (Prunus spp.; both Rosaceae) in the eastern USA since the 1930s. Successful management of G. molesta with insecticides requires careful timing of these products based on sex‐pheromone trap captures of male moths. In Pennsylvania, apple and peach orchards are often planted adjacently. Factors such as trap distance from release points, host crop, and wind were considered in relation to male moth movement within and between hosts. Our practical objective was to understand male G. molesta dispersal within and between these two hosts to achieve better management. Recapture of moths decreased over distance; the majority of moths were recaptured 50–100 m from the release point regardless of crop type. Male G. molesta released into commercial apple and peach orchards were most likely to remain in the crop of release and to not exhibit host shifts over the season, even after peach fruit were harvested. Our analyses of wind direction data with respect to recapture showed that the likelihood of recapture was similar regardless of the orientation of the traps relative to the mean wind direction at peak flight times. The apple and peach host crops appeared to affect male G. molesta dispersal to the extent that wind in orchards affects their perception of pheromone. Crop effects were most likely due to the traps closest to the release points being in the same crop as the release points.

Effects of Post-Fire Salvage Logging on Cavity-Nesting Birds and Small Mammals in Southeastern Montana

We investigated how post-fire salvage logging of Ponderosa Pine (Pinus ponderosa) affected populations of cavity-nesting birds and small mammals in southeastern Montana in 2004 and 2005. We examined two salvage and two control plots with three point-count stations and one small mammal trap site randomly distributed across each plot. We used point counts and distance sampling methods to estimate density of cavity-nesting birds on each treatment. We also searched each plot for nests and used program MARK to construct a set of candidate models to investigate variations in nest survival related to treatment, year, and time. We used live traps arranged in webs centered on trapping sites and distance sampling methods to estimate small mammal density. Habitat characteristics were also quantified on each plot. Density of all cavity-nesting birds combined and of Hairy Woodpeckers (Picoides villosus) in particular were higher on the control than the salvage treatment. Density of large trees and abundance of active cavities were higher on the control treatment. Nest cavities on the salvage treatment were most often located in non-logged watersheds. Nest survival estimates were uniformly high, with only marginal variations attributed to treatment and year. Density of Deer Mice (Peromyscus maniculatus) was higher on the salvage than the control treatment, reflecting the amount of downed woody debris created during harvest.

Serving two masters: Reconciling economic and biodiversity outcomes of brushtail possum (Trichosurus vulpecula) fur harvest in an indigenous New Zealand forest

Introduced brushtail possums (Trichosurus vulpecula) cause significant damage to biodiversity values in New Zealand native forests, but their fur and skins also represent an economic resource, particularly to small, predominantly rural Māori (indigenous people of New Zealand) communities. We used harvester interviews, trapping data and a combination of economic and spatial population models to ask whether the seemingly contradictory goals of economically-sustainable harvest and biodiversity protection can both be accommodated in native podocarp-dominated forests in the North Island of New Zealand. Harvesters expected trap-catch indices (TCIs) of 50–70% when initiating a trap-line, stopped trapping when pull-out trap-catch index (POTCI) was 26% (range 20–30%), and left trapped areas for at least 1year before returning. The effective trapping distance around a trap-line was 200m and the decline in possum captures on a line over 24 harvest-days declined exponentially from an initial 63% on day 2 to under 8% from day 21 on.The optimum strategy for sustaining an income of NZ$30,000 from harvest required access to 8–10 lines of 80 traps per year, ceasing trapping at 25% POTCI and leaving possums to recover for 3years, but this is unlikely to achieve conservation gains. Harvesters could trap to the levels required to achieve these outcomes if subsidized by management agencies that, in return, would benefit from possum control to the same degree, but at lower cost, than current standard ground-control methods.

Auger release of a deeply trapped carrier in a quantum dot

We have studied the process of Auger-induced release of an electron deeply trapped in a semiconductor quantum dot (QD). The importance of this release mechanism in connection with the termination of a dark state of the photoluminescence (PL) has not been investigated earlier. The considered release mechanism is caused by the optical illumination of the QD in the course of observations and is due to an alternative (with respect to the usual Auger process) recombination channel of a newly created electron-hole pair with the recombination energy transferred to the trapped electron. In the studied QDs of CdSe/CdS type, where the hole ground state is confined to the CdSe core while the electron ground state is extended over both the core and CdSe shell, this Auger process is characterized by the F\"orster dependence $\ensuremath{\sim}1/{r}_{0}^{6}$ of the energy transfer rate on the trap distance ${r}_{0}$ from the QD center. The efficiency of this release mechanism is comparable with the one of the usual Auger recombination, if the deep trap is located nearby the QD core. On the contrary, the release probability is small for a distant trap, so that the QD can participate in many acts of the optical creation and subsequent Auger recombination before the trapped electron is released. If there are several traps within the QD shell, their spatial distribution results in a distribution of the release rates (and therefore of PL ``off times''). We have considered several models of the trap population distribution and calculated the corresponding ``off time'' distributions. In particular, for a homogeneous spatial distribution of traps and the ``F\"orster''-like dependence ($\ensuremath{\sim}1/{r}_{0}^{6}$) of the trapping probability, the distribution of the PL off times is the power law $\ensuremath{\sim}1/{t}_{\mathrm{off}}^{\ensuremath{\alpha}}$ with the exponent $\ensuremath{\alpha}=3/2$.

Temporal distribution and spatial pattern of abundance of the Rift Valley fever and West Nile fever vectors in Barkedji, Senegal

The temporal distribution and spatial pattern of abundance of mosquito vectors of Rift Valley fever (RVf) and West Nile fever (WNf) were studied during the 2005 and 2006 rainy seasons at Barkedji, Senegal. Mosquitoes were collected every two weeks with CDC light traps with dry ice at 79 sites including temporary ponds, barren, shrubby savannah, wooded savannah, steppes, and villages at different distances (between 0 and 600 m) from the nearest pond. The temporal distributions of these vectors varied between 2005 and 2006 and were positively correlated with rainfall for Aedes (Aedimorphus) vexans Patton, with rainfall after a lag time of one month for Culex (Culex) poicilipes (Theobald) and Culex (Culex) neavei Theobald. All the vectors had their highest abundances and parity rates between September and November. The highest vector abundances were observed in the barren and temporary ponds. The distance of trap location to the nearest ponds was negatively correlated to the abundance of the vectors. Taking into account the linear regression equations, it was predicted that mosquitoes would not disperse and be collected by the light trap, up to 1,500 m to the nearest ponds. The implications of these findings in the epidemiology and control of RVF and WNF at Barkedji are discussed.

Sensitivity Study of Simulation Parameters Controlling CO2 Trapping Mechanisms in Saline Formations

The primary purpose of this study is to understand quantitative characteristics of mobile, residual, and dissolved CO2 trapping mechanisms within ranges of systematic variations in different geologic and hydrologic parameters. For this purpose, we conducted an extensive suite of numerical simulations to evaluate the sensitivities included in these parameters. We generated two-dimensional numerical models representing subsurface porous media with various permutations of vertical and horizontal permeability (kv and kh), porosity (\({\phi}\)), maximum residual CO2 saturation (\({S_{\rm gr}^{\max}}\)), and brine density (ρbr). Simulation results indicate that residual CO2 trapping increases proportionally to \({k_{\rm v}, k_{\rm h}, S_{\rm gr}^{\max}}\) and ρbr but is inversely proportional to \({\phi.}\) In addition, the amount of dissolution-trapped CO2 increases with kv and kh, but does not vary with \({\phi }\) , and decreases with \({S_{\rm gr}^{\max}}\) and ρbr. Additionally, the distance of buoyancy-driven CO2 migration increases proportionally to kv and ρbr only and is inversely proportional to \({k_{\rm h}, \phi }\) , and \({S_{\rm gr}^{\max}}\) . These complex behaviors occur because the chosen sensitivity parameters perturb the distances of vertical and horizontal CO2 plume migration, pore volume size, and fraction of trapped CO2 in both pores and formation fluids. Finally, in an effort to characterize complex relationships among residual CO2 trapping and buoyancy-driven CO2 migration, we quantified three characteristic zones. Zone I, expressing the variations of \({S_{\rm gr}^{\max}}\) and kh, represents the optimized conditions for geologic CO2 sequestration. Zone II, showing the variation of \({\phi}\) , would be preferred for secure CO2 sequestration since CO2 has less potential to escape from the target formation. In zone III, both residual CO2 trapping and buoyancy-driven migration distance increase with kv and ρbr.

Preliminary investigations into the use of trap crops to control Agriotes spp. (Coleoptera: Elateridae) in potato crops

A field trial was conducted to investigate the use of peas (Pisum sativum cv. Valverde), wheat (Triticum aestivum cv. Capo) and oilseed radish (Raphanus sativus var. oleiformis cv. Adagio) as trap crops to control wireworm in potato fields. We investigated the efficacy of trap crops and distance of attraction by counting larvae in both potato and trap crop rows. Wireworms of the genera Agriotes, Adrastus and Hemicrepidius were observed. In the plots planted with peas as a trap crop, significantly more wireworms were observed than in the other treatments, which was clearly due to the influence of the trap crop pea. The potato rows 0.75 m away from the peas showed 2.4 times more larvae than the potato rows 1.5 m away. This may be due to a decrease of the peas’ attractiveness over time (Miles and Petherbridge 1927), with wireworms that were initially attracted to the peas moving back to the nearby potatoes. In the plots planted with wheat, oilseed radish and the control (bare soil instead of a trap crop), there was no significant difference in numbers of larvae between the potato rows. In the control plots, significantly more larvae were found in the potato rows than in the bare soil. We assessed the damage to potato tubers by weighing them and counting the wireworm holes. Our results indicate that peas are more attractive to wireworms than potatoes and might be an effective trap crop if the right timing and spacing relative to the potatoes is found.

Trapping Rayleigh particles using highly focused higher-order radially polarized beams

The optical trapping characteristics of highly focused higher-order radially polarized beams (R-TEMp1*) acting on a Rayleigh particle are studied theoretically. Numerical results show that as the order p of beam increases and the numerical aperture NAo of the objective decreases, the axial trap distance increases but the trap depth and maximum restoring force decreases. In a limit of NAo=1, three higher-order R-TEMp1* beams of p=1, 2, 3, like the fundamental lowest-order radially polarized beam of p=0, can three-dimensionally trap a particle to the focus but the axial trap stiffness decreases with the increase of p. When NAo=0.95, the focus is still a stable trap point for the two beams of p=0 and 1 but it becomes an unstable trap point for the two beams of p=2 and 3. The trap stability is also discussed for higher-order radially polarized beam illumination.

Dynamics of two trapped Brownian particles: Shear-induced cross-correlations

The dynamics of two Brownian particles trapped by two neighboring harmonic potentials in a linear shear flow is investigated. The positional correlation functions in this system are calculated analytically and analyzed as a function of the shear rate and the trap distance. Shear-induced cross-correlations between particle fluctuations along orthogonal directions in the shear plane are found. They are linear in the shear rate, asymmetric in time, and occur for one particle as well as between both particles. Moreover, the shear rate enters as a quadratic correction to the well-known correlations of random displacements along parallel spatial directions. The correlation functions depend on the orientation of the connection vector between the potential minima with respect to the flow direction. As a consequence, the inter-particle cross-correlations between orthogonal fluctuations can have zero, one or two local extrema as a function of time. Possible experiments for detecting these predicted correlations are described.

Model for the off-time distribution in blinking quantum dots

Abstract The understanding of blinking quantum dots (QDs) is an open problem since more than a decade. We have investigated the off-time distribution of a semiconductor QD on the basis of an Auger-induced release process of an electron deeply trapped in the QD shell. This release process has not yet been treated in the literature explicitly and starts with the optical generation of an additional electron–hole pair in the off-state of a QD, characterized by a valence band hole in the core and a trapped electron in the shell. This additional pair subsequently recombines and the recombination energy is transferred by an Auger process to the trapped electron. We discuss the efficiency of the release process as compared to the quenching process. For a deep trap occupation density ∼ 1 / r 0 6 ( r 0 is the trap distance from the QD center) and a Forster-like release rate, we arrive at an off-time distribution ∼ 1 / t off α with α = 3 / 2 in agreement with experimental findings in many QDs.

Density‐dependent impacts of exotic conifer invasion on grassland invertebrate assemblages

Summary 1. Globally, temperate grasslands have been heavily modified by agricultural intensification. The ecological integrity of many remaining semi‐natural grasslands is further threatened by the encroachment of invasive alien woody plant species, such as conifers. 2. Although the ecological impact of conifers is often inferred to be directly related to increasing conifer density at invaded sites, interpretation of these density‐dependent effects on native biodiversity is almost always confounded by strong correlations between density and time since invasion. Here, we isolate the direct effects of exotic conifer density on native invertebrate assemblages from the confounding effects due to time since invasion, by establishing replicated experimental plantings of the invasive Pinus nigra (densities of 400, 800, 1600, 2500 and 3500 trees per ha, established in 1993) in New Zealand. 3. From the 29 549 invertebrates captured, the relative abundance of major classes and orders was largely unaffected by conifer invasion at densities below 800 trees per ha at age 14 years, but differed substantially in higher‐density conifer stands (canopy cover &gt;50%). At the species level, beetle species composition was highly sensitive to conifer invasion at densities as low as 400 trees per ha at age 14 years. Changes in beetle species composition were correlated with reduced soil moisture, increases in canopy cover, and trap distance from the nearest semi‐natural grassland. 4. Synthesis and applications. The effects of exotic conifer invasion on grassland invertebrate assemblages were strongly dependent on conifer density. In our study, the negative effects of conifer invasion on biodiversity were comparatively low at densities below ≤800 trees per ha at 14 years after invasion. To conserve invertebrate diversity in semi‐natural grasslands we recommend a dual focus of conservation actions targeting: (i) immediate control, or thinning, of high density conifer infestations (&gt;800 trees per ha) to restore habitat to a state suitable for grassland species, and (ii) longer‐term removal of sparse, pre‐coning infestations in order to prevent further spread. We propose the use of canopy cover as a proxy for the confounded relationship between conifer density and time since invasion.

Dispersal ofRhyzopertha dominica(Coleoptera: Bostrichidae) in Different Habitats

The lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), a serious pest of stored cereal grains, is widely distributed and has been collected in different habitats in North America, such as those from agricultural and nonagricultural settings. Our objective was to study the dispersal distances and direction of dispersal by R. dominica after external marking using fluorescent powder, releasing marked beetles, and recapturing adults using pheromone traps in distinctively different ecological habitats, wooded sites and open grasslands, for 2 consecutive yr. The recapture rate of marked beetles ranged from 6 to 26% in both sites and was generally higher in the wooded site than the open field site for both years. There was a significant difference in dispersal distances between wooded and open sites. Mean dispersal distances in the wooded site ranged from 337 to 375 m, whereas in the open site, they varied from 261 to 333 m. Trap captures for both marked and feral beetles were related to the ambient temperature such that increase in trap captures occurred with increasing temperature. Significant differences were observed for directional movement of R. dominica in both sites and indicated that most beetles dispersed in the northwest direction. Correlation analyses showed that the relationship between numbers of marked-released-recaptured beetles significantly decreased with increasing trap distances. Understanding dispersal distances and directions provide insight to flight behavior of R. dominica and to the relationship between ecologically diverse breeding habitats. Knowledge of R. dominica habitat ecology outside of grain storage facilities may be useful in designing suitable management tactics to minimize the onset of infestations in grain storages.

Longer axial trap distance and larger radial trap stiffness using a double-ring radially polarized beam

The optical trapping forces acting on a metallic Rayleigh particle are calculated for the case where a double-ring-shaped radially polarized beam is applied. The influence of the off-focus distance and the off-axis distance of a trapping particle on the trapping force is investigated. Compared with the use of the conventional single-ring-shaped radially polarized beam, the longer axial trap distance and the larger radial trap stiffness are predicted using a double-ring-shaped radially polarized beam in an optical trap. These features are useful for improving the trapping ability of an optical trap system where a longer axial trap distance is needed.