THE EFFECTS OF POLARIZATION UPON THE STEEL WIRE-NITRIC ACID MODEL OF NERVE ACTIVITY

The active process in a short length of steel wire passivated by 65 per cent nitric acid has been observed under the influence of a polarizing current, and the form of the potential recorded by the cathode ray oscillograph. In the passive wire, 80 per cent of the total potential drop takes place at the anode, 20 per cent at the cathode. The change from active to passive states, as measured by the potential change, is very abrupt compared to the duration of activity and the potential curve at a point on the wire is probably almost rectangular. The duration of the refractory state is decreased at the anode and increased at the cathode, as in nerve. This fact is against the idea that reactivity after passivation results from a partial reduction of an oxide layer. Soft iron wire passivated by anodal polarization repassivates after activation in acid of a dilution that fails to passivate it initially. It soon becomes rhythmic with a very short refractory phase, and then reacts continuously. Such a wire exhibits a very sharp alternation between a dark brown oxide coat during activity, and a bright clean surface during passivation. A passive steel wire in nitric acid shows many of the characteristics of an inert electrode such as platinum, and it may be inferred that, superposed upon the primary passivation potential, there exists an electrode or oxidation-reduction potential equilibrium between the effects of the various constituents of the solution. It is suggested that the phenomena of nerve-like reactivity in this system may involve an alternation between two protective coatings of the steel wire. During activity, the surface becomes mechanically coated with a brown oxide. If this coating does not adhere, due to gas convection or to rapid solution of the oxide, passivation does not result. Under sufficiently intense oxidizing conditions, a second oxide coat may form in the interstices of the first, and cover the surface as the first coating dissolves off. This furnishes the electrochemical protection of passivation, which is followed by the gradual attainment of electrode equilibrium with the solution.     

Factors affecting disruption of biological material by an ultrasonically vibrating wire

A transversely oscillating wire at 20 kHz has recently been used successfully for the dispersion of cell aggregates. The shape of the tip of the wire is here shown to be critical in producing these effects. In low viscosity suspensions the onset of markedly increased mixing of the treatment vessel contents, which depends on the proximity of the wire to the container side, has been shown to coincide with the onset of cell lysis.     

Guanaco (Lama guanicoe) mortality by entanglement in wire fences

Wire fences are widely used in rangelands around the world and may have a negative impact on wildlife that varies among species and habitats. The guanaco (Lama guanicoe) is the largest Patagonian ungulate and though entanglement in wire fences is frequently reported, its impact on guanaco populations has not been previously evaluated. We estimated annual mortality rate of wild guanacos due to entanglement in wire fences and evaluated whether the frequency of entanglement was age-dependent in the two wire-fence designs traditionally used in Patagonian sheep ranches. We found that annual yearling mortality on fences (5.53%) was higher than adult mortality (0.84%) and was more frequent in ovine (93 cm high) than bovine (113 cm) fences. Most guanacos died entangled by their legs in the highest wire when trying to jump over the fence. Our results suggest that guanacos are more likely to die due to fence entanglement than ungulates studied in other regions. Indirect effects of wire fences should also be considered as they may act as semi-permeable barriers for guanaco populations. We suggest removal of unnecessary wire fences and replacement by guanaco-friendly fences, like high-tensile electric fences that may reduce mortality and barrier-effect on guanaco populations.     

DRY-ROT DISEASE OF THE POTATO

A study has been made of the incidence of dry rot in seed potatoes in relation to commercial handling methods, and it has been shown that infection following grading by mechanical reciprocating riddles fitted with bare wire screens is more serious than that following normal handling at harvest or during transport. Hand picking, hand riddling and the use of rubber-spool graders or rubber-coated screens reduced infection by varying amounts. The higher incidence of the disease in 'transported' as against 'home-saved' seed is regarded as being due to machine grading of such stocks some months prior to planting.
Contamination of stores or boxes has not been found to play any material part in the spread of infection under commercial conditions unless tubers are roughly handled during storage. As contact infection has been found to be rare, it is considered that the practice of 'picking over' stocks during the winter to remove diseased tubers is unnecessary and may lead to further infection.
In addition to wounds, lesions of both blight and powdery scab, but not common scab, have been found to be a means of infection.     

Squid giant axons. A model for the neuron soma?

Insertion of electrically floating wires along the axis of a squid giant axon produces an apparent increase in diameter in the region where the wire surface has been treated to give it a low resistance. The shape of action potentials propagating into this region depend upon the surface resistance (and the length) of the wire. As this segment's internal resistance is lowered by reducing the wire's surface resistance, the following characteristic sequence of changes in the action potential is seen at the transition region: (a) the duration increases; (b) two peaks develop, the first one generated in the normal axon region and the second one generated later in the axial wire region, and; (c) blockage occurs (for a very low resistance wire). Action potentials recorded at the membrane region near the tip of the axial wire in (b) resemble those recorded at the initial segment of neurons upon antidromic invasions. Squid axon action potentials propagated from a normal region into that containing the low resistance wire also resemble antidromic invasions recorded in neuron somas. Hyperpolarizing current pulses applied through the wire act as if the wire surface resistance was momentarily reduced. For example, the two components of the action potential recorded at the axial wire membrane region noted in (b) can be sequentially blocked by the application of increasing hyperpolarizing current through the wire. Similar effects are seen when hyperpolarizing currents are injected into motoneuron somas. It is concluded that the geometrical properties of the junction of a neuron axon with its soma may be in themselves sufficient to determine the shape of the action potentials usually recorded by microelectrodes.     

A review of projection radiography of plasma and biological objects in X-Pinch radiation

A review of studies on the X-pinch as a radiation source for X-ray projection shadow radiography (XPSR) and X-ray absorption spectroscopy (XAS) is presented. The ultimate capabilities of the techniques and ways of their achievement are considered. XPSR has been successfully used to study high-energy-density plasma objects, in particular, exploding wires and wire arrays. Using XPSR, the internal structure and dynamics of a wire explosion and wire array implosion have been investigated for the first time, which has made it possible to develop an adequate consistent theory of the processes occurring in the wire loads of generators with currents from several units of kiloamperes to a few tens of megamperes. The use of XAS for diagnostics of wire loads has allowed one for the first time to measure the parameters of matter in the wire core and plasma corona of the load. X-ray images of various biological objects have obtained, including those with the use of the phase contrast method. This review is a logical continuation of the review “Х-Pinch” [Plasma Phys. Rep. 41, 319, 493 (2015)], in which the Х-pinch as a physical object was considered.     

The "shielding" effect of the guide wire during coronary brachytherapy with P-32 source

Intracoronary beta irradiation (use of beta radiation for intracoronary irradiation) is an effective method in reducing neointimal proliferation after successful angioplasty and stent implantation. However, long-term results may be influenced by absolute dose and by the homogeneity in dose distribution. In our study, we investigated dose perturbation due to the presence of a conventional guide wire during irradiation. The Galileo III centering catheter and P-32 beta source were used. The 55 MD GAF Chromic foil was positioned within a phantom made of PMMA. The dose distribution at cylindrical surfaces has been assessed using GAF Chromic dosimetric foil MD55 (Nuclear Associates, USA). Our study demonstrated the significant dose reduction of 46% in the most "shaded" area. The dose reduction to 80% or less occupy the 60 degrees sector. This phenomenon can cause progression of late restenosis. In conclusion, the results suggest that technical improvements in centering catheter construction should be made to eliminate the "shielding" effect of the guide wire.     

Choice of Tethering Material Influences the Magnitude and Significance of Treatment Effects in Whitefly Electrical Penetration Graph Recordings

The electrical penetration graphing or electropenetrography (EPG) technique is essential for understanding interactions of hemipteran insects with their host plants. Typically, 10–12.5 μm diameter gold wire is used as the tethering material in EPG studies. This wire was originally chosen based on suitability for aphids, but application of the EPG technique to other insects necessitates testing of alternative tethering materials that permit natural foraging and probing behavior. Whiteflies are one group for which EPG studies are increasing, with most researchers using 10 or 12.5 μm diameter gold wire even though these insects are smaller than aphids and very different in mobility. However, 2.5 μm diameter Wollaston process platinum wire has been used for a subset of EPG studies and seems to permit more natural movement and feeding behaviors. Here, we compared EPG variables derived from recordings of the sweet potato whitefly (Bemisia tabaci) tethered with 12.5 μm diameter gold wire or 2.5 μm diameter platinum wire. On a suitable host, gold-tethered whiteflies had reduced phloem phases, which are indicative of host plant acceptance, compared to platinum-tethered whiteflies. When we included a treatment known to reduce plant quality (methyl jasmonate application), platinum-tethered whiteflies exhibited expected reductions in EPG variables related to host acceptance, while gold-tethered whiteflies either had no response, or the opposite response. Our results indicate that tethering material strongly influences the outcome of EPG experiments, with important consequences for evaluations of host plant resistance, putative instances of plant virus manipulation, and feeding variables associated with virus transmission.     

Wire codes,magnetic fields,and childhood cancer

Childhood cancer has been modestly associated with wire codes, an exposure surrogate for power frequency magnetic fields, but less consistently with measured fields. We analyzed data on the population distribution of wire codes and their relationship with several measured magnetic field metrics. In a given geographic area, there is a marked trend for decreased prevalence from low to high wire code categories, but there are differences between areas. For average measured fields, there is a positive relationship between the mean of the distributions and wire codes but a large overlap among the categories. Better discrimination is obtained for the extremes of the measurement values when comparing the highest and the lowest wire code categories. Instability of measurements, intermittent fields, or other exposure conditions do not appear to provide a viable explanation for the difference between wire codes and magnetic fields with respect to the strength and consistency of their respective association with childhood cancer. Bioelectromagnetics 18:99–110, 1997. © 1997 Wiley-Liss, Inc.     

Comparative Reliability Studies and Analysis of Au,Pd-Coated Cu and Pd-Doped Cu Wire in Microelectronics Packaging

This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (Pd) coated Cu and Pd-doped Cu wires used in fineline Ball Grid Array (BGA) package. Intermetallic compound (IMC) thickness measurement has been carried out to estimate the coefficient of diffusion (D_o) under various aging conditions of different bonding wires. Wire pull and ball bond shear strengths have been analyzed and we found smaller variation in Pd-doped Cu wire compared to Au and Pd-doped Cu wire. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of Cu. The obtained weibull slope, β of three bonding wires are greater than 1.0 and belong to wearout reliability data point. Pd-doped Cu wire exhibits larger time-to-failure and cycles-to-failure in both wearout reliability tests in Highly Accelerated Temperature and Humidity (HAST) and Temperature Cycling (TC) tests. This proves Pd-doped Cu wire has a greater potential and higher reliability margin compared to Au and Pd-coated Cu wires.     

Studies on the catalytic ability of palladium wire, foil and sponge in the Suzuki-Miyaura cross-coupling

Different forms of metallic palladium (wire, foil and sponge) have been tested as potential catalysts in the Suzuki-Miyaura cross-coupling. All samples showed to be catalytically active for both electron-poor and electron-rich aryl bromides combined with a variety of arylboronic acids. Palladium wire has been recycled six times without decrease of activity. A series of poisoning experiments demonstrated that the true catalyst is a soluble form of palladium arising from a leaching process. Interestingly, metal leaching from palladium foil has been clearly evidenced by SEM.     

High gradient magnetic separation of erythrocytes

The high gradient magnetic separation technique has been applied to separate paramagnetic erythrocytes from a cell suspension that also contained diamagnetic cells. Paramagnetism was induced in the red blood cells by oxidizing the iron atoms in the cell hemoglobin to the ferric state (methemoglobin). Diamagnetic cells were either untreated erythrocytes, containing oxyferrohemoglobin, or leukocytes in a suspension of mouse spleen cells. Cell suspensions were passed through a column containing 40 micron diameter stainless steel wire in a high magnetic field (33 kG). The paramagnetic cells were retained on the surface of the wire while the diamagnetic cells passed through. Elution of the paramagnetic cells was accomplished by removing the column from the magnet, in effect turning off the field.     

Protective management of trees against debarking by deer negatively impacts bryophyte diversity

When wildlife populations become too large, they impact other flora and fauna within the ecosystems that they inhabit. For example, the recent rise in population numbers of sika deer in Japan has led to the stripping of bark from tree overstories in forested areas. This has led to protective management actions, such as wrapping the trunks of trees in wire mesh. The present study investigates the impact of this management action on epiphytic diversity at Mt. Ohdaigahara, which is one of the hotspots for bryophyte diversity in Japan. The correlation between the diversity of epiphytic bryophytes and environmental variables was examined, including the presence/absence of wire mesh protection. A generalized linear model showed that species richness and bryophyte cover was significantly correlated with both tree diameter (at 1.5 m height) and tree density (P < 0.01), but negatively correlated with wire mesh protection. Inductively coupled plasma-mass spectrometry analysis showed a significant 3- to 6-fold higher concentration of zinc in bryophytes occupying tree bark under wire mesh protection than for those without wire mesh. Hence, the high sensitivity of bryophytes to zinc accumulation, as a result of toxicity caused by galvanized iron mesh, has led to the loss of species richness and bryophyte cover on tree trunks. Furthermore, other heavy metals found in wire mesh may also contribute to the negative effect on bryophytes. Therefore, to establish best practices for biodiversity conservation that include bryophytes, materials that are free of heavy metals should be preferentially used for tree protection.     

Influence of prior exposure to wood shavings on feather pecking, dustbathing and foraging in adult laying hens

It has been proposed that chicks acquire substrate preferences during an early 'sensitive' period. If a suitable substrate is absent during this period birds may develop alternative preferences for pecking at feathers. The aim of this study was to examine whether early substrate exposure has durable effects on the subsequent behaviour of adult hens. The effects of duration of substrate exposure, substrate change, age at exposure and time since exposure on adult bird behaviour were examined. From days 1 to 210, 144 laying strain birds were housed in pairs in pens with wire floors. The floors were replaced with solid floors covered in wood shavings at different ages and for different durations by allocation to 1 of 12 treatments. Adult birds that had never experienced shavings performed significantly more feather pecking than birds in any other treatment group. Thus, exposure to shavings, even for the minimum exposure duration of 10 days, was protective. However, current substrate was of great importance and adult birds housed on shavings performed significantly more ground pecking and less feather pecking than birds on wire, regardless of previous experience. From day 211 all hens were given shavings or straw, presented alternately for five 24h sessions over 10 consecutive days. Birds foraged on both substrates and their foraging behaviour was not influenced by previous experience. Dustbathing occurred primarily on shavings and was significantly influenced by the age at which birds had previously been exposed to shavings. Dustbathing on shavings was fairly constant throughout the 10-day test period in all groups, suggesting that relatively stable preferences had developed. A secondary 'sensitive period' for the formation of adult dustbathing substrate preference may have superseded the early 'imprinting' process. However, adult behaviour was generally flexible and strongly influenced by current substrate.     

Description of a new computer wire coding method and its application to evaluate potential control selection bias in the Savitz et al. childhood cancer study

We developed a new computer wire coding method and then applied it to investigate the suggestion that control selection bias might explain the observed association between wire codes and childhood cancer made in the study conducted by Savitz et al. in the Denver area. The computer wire coding method used a geographic information system approach with data on the local distribution electric system and from tax assessor records. Individual residences were represented as a circle scaled to the ground floor area of the residence and centered on the lot centroid. The wire code of the residence was determined from the distance between the circle and the relevant power line, and from the current carrying capacity of that line. Using this method, wire codes were generated for 238 290 residences built before 1986, the time of the Savitz et al. study, in the Denver metropolitan area. We then attempted to reconstruct the 1985 population of hypothetically eligible control children in the Denver metropolitan area by using 1980 census data. Since data were not available to locate the children in each residence within a census block, uniform, Poisson, and negative binomial distributions were used to randomly assign children to residences. To evaluate the likelihood of the wire code distribution of the controls selected by Savitz et al., 100 random trials were conducted for each distribution, matching two controls to each case. The odds ratios between childhood cancer and very high current configuration (VHCC) wire codes were reduced when the assigned controls were used, suggesting control selection bias may have been present. However, control selection bias is unlikely to account for all the reported association between childhood cancer and wire codes in the Savitz et al. study.     

Comparison of the effectivity of different snare types for collecting and retaining hair from Eurasian Lynx (Lynx lynx)

Genetic methods are increasingly being used as noninvasive tools to survey populations of wild animals. One challenge of these methods is the sampling of genetic material from the target species. Genetic material of various predators, such as bears, canids, and felids, has been successfully obtained from both hair trapped in snares and scat. However, there is currently no standard procedure for sampling genetic material from the Eurasian Lynx (Lynx lynx). We tested established and newly developed hair snares in two near-natural lynx enclosures in the Bavarian Forest National Park. All snares consisted of a wooden post; they differed in the type of material attached to the post for snaring hair: carpet (velour with 40 nails), wildcat (spruce wood with 2–3?mm deep, horizontal and diagonal ridges), wire brush, doormat, or rubber bands (250?g of rubber bands wrapped around the post). We determined the acceptance of the hair snares by the animals by observing their behavior with the aid of video cameras. The number of rubbing events on the different trap types did not significantly differ, but the rubbing duration was longer for the doormat hair snare. The wire brush hair snare collected the highest total amount of hair and — beside the carpet — the highest amount of hair per unit of time. Almost all hair trapped on the wire brush snare were retained during a 2-week exposure to the elements outside of the enclosures. The results of our study may hold for other felid species with hair characteristics similar to those of lynx.     

Training cattle to control by electric fences

Since cattle learn respect for electric fences, it may be possible to use single electric wires as permanent fences on beef-cattle properties. Two experiments are reported in this paper. The first investigated a method of training inexperienced cattle in a small yard before release to paddocks fenced with a single wire. The training yard consisted of a strong conventional fence with a single electric wire attached. It confined animals in a small area, thus encouraging them to investigate, receive shock and learn respect. After a day of such training, the animals were automatically photographed at each approach to a single wire in a test paddock and compared with an untrained group in a similar test paddock. Although no animals broke through in either group, it is clear that trained animals more quickly recognized the wire and showed respect by not touching it.The second experiment demonstrated the great respect cattle had for a single electrified wire after training, because it prevented hungry heifers from going to eat hay which they had been conditioned to eat.It is concluded that training is simple and provides a controlled learning period to give increased respect for electrified wires and to minimize the risk of animals breaking through when first released to paddocks with electrified boundaries.     

Unpacking of a Crumpled Wire from Two-Dimensional Cavities

The physics of tightly packed structures of a wire and other threadlike materials confined in cavities has been explored in recent years in connection with crumpled systems and a number of topics ranging from applications to DNA packing in viral capsids and surgical interventions with catheter to analogies with the electron gas at finite temperature and with theories of two-dimensional quantum gravity. When a long piece of wire is injected into two-dimensional cavities, it bends and originates in the jammed limit a series of closed structures that we call loops. In this work we study the extraction of a crumpled tightly packed wire from a circular cavity aiming to remove loops individually. The size of each removed loop, the maximum value of the force needed to unpack each loop, and the total length of the extracted wire were measured and related to an exponential growth and a mean field model consistent with the literature of crumpled wires. Scaling laws for this process are reported and the relationship between the processes of packing and unpacking of wire is commented upon.     

Blood-seeking horseflies prefer vessel-imitating temperature gradients on host-mimicking targets: Experimental corroboration of a new explanation of the visual unattractiveness of zebras to tabanids

Several hypotheses tried to explain the advantages of zebra stripes. According to the most recent explanation, since the borderlines of sunlit white and black stripes can hamper thermal vessel detection by blood-seeking female horseflies, striped host animals are unattractive to these parasites which prefer hosts with a homogeneous coat, on which the temperature gradients above blood vessels can be detected more easily. This hypothesis has been tested in a field experiment with horseflies walking on a grey barrel with thin black stripes which were slightly warmer than their grey surroundings in sunshine, while in shade both areas had practically the same temperature. To eliminate the multiple (optical and thermal) cues of this test target, we repeated this experiment with improved test surfaces: we attracted horseflies by water- or host-imitating homogeneous black test surfaces, beneath which a heatable wire ran. When heated, this invisible and mechanically impalpable wire imitated thermally the slightly warmer subsurface blood vessels, otherwise it was thermally imperceptible. We measured the times spent by landed and walking horseflies on the test surface parts with and without underlying heated or unheated wire. We found that walking female and male horseflies had no preference for any (wired or wireless) area of the water-imitating horizontal plane test surface on the ground, independent of the temperature (heated or unheated) of the underlying wire. These horseflies looked for water, rather than a host. On the other hand, in the case of host-imitating test surfaces, female horseflies preferred the thin surface regions above the wire only if it was heated and thus warmer than its surroundings. This behaviour can be explained exclusively with the higher temperature of the wire given the lack of other sensorial cues. Our results prove the thermal vessel recognition of female horseflies and support the idea that sunlit zebra stripes impede the thermal detection of a host‘s vessels by blood-seeking horseflies, the consequence of which is the visual (non-thermal) unattractiveness of zebras to horseflies.     

Intravascular brachytherapy to prevent restenosis: dosimetric considerations.

Acute myocardial infarction is often the result of occlusion of one or more coronary arteries. Occlusion and restenosis (re-closing of the vessel) are principal reasons that percutaneous transluminal coronary angioplasty (PTCA) may fail to provide long-term benefit. PTCA has been a popular treatment, which is less invasive than surgeries involving revascularization of the myocardium, promising a better quality of life for patients. Unfortunately, the rate of restenosis after balloon angioplasty is high (approximately 30-50% in the first year after treatment). Recent data suggest that intraluminal irradiation of coronary arteries in conjunction with balloon angioplasty and/or stent implantation reduces the proliferation of smooth muscle cells and neointima formation, thereby inhibiting restenosis. In order to study radiation dosimetry in the patient and for this therapy, dose distributions for electrons and photons, with discrete energies, were simulated for blood vessels of diameter 1.5, 3 and 4.5 mm irradiated with balloon and wire sources. Electron and photon transport was performed in a simple model representing the system used for irradiation using the MCNP 4B code (Monte Carlo N-Particles). Specific calculations for balloon and wire sources were also carried out for a few radionuclides. In this work, strengths and drawbacks conceming the use of each radionuclide simulated, as well as source geometries are discussed. The dosimetry performed in this study will improve understanding of the benefit-to-risk ratio in intracoronary brachytherapy.