The effect of hunger level on predation dynamics in the spider Nesticodes rufipes: a functional response study

It is well known that a predator has the potential to regulate a prey population only if the predator responds to increases in prey density and inflicts greater mortality rates. Predators may cause such density-dependent mortality depending on the nature of the functional and numerical responses. As spiders are usually faced with a shortage of prey, the killing behavior of the spider Nesticodes rufipes at varying densities of Musca domestica was examined here through laboratory functional response experiments where spiders were deprived of food for 5 (well-fed) or 20 days (hungry). An additional laboratory experiment was also carried out to assess handling time of spiders. The number of prey killed by spiders over 24- and 168-h periods of predator-prey interaction was recorded. Logistic regression analyses revealed the type II functional response for both well-fed and hungry spiders. We found that the lower predation of hungry spiders during the first hours of experimentation was offset later by an increase in predation ( explained by estimated handling times), resulting in similarity of functional response curves for well-fed and hungry spiders. It was also observed that the higher number of prey killed by well-fed spiders over a 24- h period of spider-prey interaction probably occurred due to their greater weights than hungry spiders. We concluded that hungry spiders may be more voracious than well-fed spiders only over longer time periods, since hungry spiders may spend more time handling their first prey items than well-fed spiders.

SPH simulations of clumps formation by dissipative collisions of molecular clouds - II. Magnetic case

We performed computer simulations of interstellar cloud-cloud collisions using the three-dimensional smoothed particle magnetohydrodynamics method. In order to study the role of the magnetic field on the process of collision-triggered fragmentation, we focused our attention on head-on supersonic collisions between two identical spherical molecular-clouds. Two extreme configurations of the magnetic field were adopted: parallel and perpendicular to the initial clouds motion. The initial magnetic field strength was approximately 12.0 muG. In the parallel case, much more of the collision debris were retained in the shocking region than in the non-magnetic case where gas escaped freely throughout the symmetry plane. Differently from the non-magnetic case, eddy-like vortices were formed. The regions of highest vorticity and the the regions of highest density are offset. We found clumps formation only in the parallel case, however, they were larger, hotter and less dense than in the analogous non-magnetic case. In the perpendicular case, the compressed field works as a magnetic wall, preventing a stronger compression of the colliding clouds. This last effect inhibits direct contact of the two clouds. In both cases, we found that the field lines show a chaotic aspect in large scales. Also, the field magnitude is considerably amplified in the shock layer. However, the field distribution is almost coherent in the higher density regions.

Structure and Growth Kinetics of 3-Glycidoxypropyltrimethoxysilane-Derived Organic/Silica Hybrids at Different Temperatures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ultra-sonografia bidimensional em tempo real do bulbo ocular de cães (Canis familiaris, Linnaeus, 1758) com opacificação de meios transparentes. Emprego do transdutor mecânico setorial de 7,5 MHz com almofada de recuo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

High resolution spectroscopy of (CH3OH)-C-13 around the 10R(20) CO2 laser emission: New FIR laser lines, frequency measurements and assignments

We investigated the IR absorption spectrum of (CH3OH)-C-13 around the frequency of the 10R(20) CO2 laser line. We found two absorption lines which can be excited by 10R(20) and studied the FIR laser emissions excited by this pump line using a waveguide CO2 laser of 300 MHz tunability: We report two new FIR laser lines of large offset, not previously observed due to their weakness and closeness to other stronger lines. We measured the frequencies of five FIR laser lines for the first time by an accurate heterodyne technique and present the complete assignments of the IR-FIR laser systems relative to this pump line. Furthermore we present new frequency values for two FIR laser lines whose frequencies had been previously wrongly measured. Copyright (C) 1997 Elsevier B.V. Ltd.

The (CH3OH)-C-13 optically pumped far-infrared laser: New lines and frequency measurements

We report 18 new laser lines from (CH3OH)-C-13 generated in an optically pumped far-infrared laser; the laser lines are in the range of 54.2-420 mu m and are all characterized in wavelength, polarization relative to the pumping CO2 radiation, and pump offset relative to the CO2 center frequency, the frequencies of seven of these new lines along with 10 previously reported lines were measured by an accurate heterodyne technique, mixing them in a metal-insulator-metal (MIM) point contact diode, with another laser line of known frequency.

The acid-base impact of free water removal from, and addition to, plasma

Water, compared with plasma at a pH of 7.4, is a weak acid. The addition of free water to a patient should have an acidifying effect (dilutional acidosis) and the removal of it, an alkalinizing effect (concentrational alkalosis). The specific effects of free water loss or gain in a relatively complex fluid such as plasma has, to the authors' knowledge, not been reported. This information would be useful in the interpretation of the effect of changes in free water in patients. Plasma samples from goats were either evaporated in a tonometer to 80% of baseline volume or hydrated by the addition of distilled water to 120% of baseline volume. The pH and partial pressure of carbon dioxide, sodium, potassium, ionized calcium, chloride, lactate, phosphorous, albumin, and total protein concentrations were measured. Actual base excess (ABE), standard bicarbonate, anion gap, strong ion difference, strong ion gap, unmeasured anions, and the effects of sodium, chloride, phosphate, and albumin changes on ABE were calculated. Most parameters changed 20% in proportion to the magnitude of dehydration or hydration. Bicarbonate concentration, however, increased only 11% in the evaporation trial and decreased only -2% in the dehydration trial. The evaporation trial was associated with a mild, but significant, metabolic alkalotic effect (ABE increased 3.2 mM/L), whereas the hydration trial was associated with a slight, insignificant metabolic acidotic effect (ABE decreased only 0.6 mM/L). The calculated free water ABE effect (change in sodium concentration) was offset by opposite changes in calculated chloride, lactate, phosphate, and albumin ABE effects.

TRICUT: a program to clip triangle meshes using the rapid and triangle libraries and the visualization toolkit

An efficient technique to cut polygonal meshes as a step in the geometric modeling of topographic and geological data has been developed. In boundary represented models of outcropping strata and faulted horizons polygonal meshes often intersect each other. TRICUT determines the line of intersection and re-triangulates the area of contact. Along this line the mesh is split in two or more parts which can be selected for removal. The user interaction takes place in the 3D-model space. The intersection, selection and removal are under graphic control. The visualization of outcropping geological structures in digital terrain models is improved by determining intersections against a slightly shifted terrain model. Thus, the outcrop line becomes a surface which overlaps the terrain in its initial position. The area of this overlapping surface changes with respect to the strike and dip of the structure, the morphology and the offset. Some applications of TRICUT on different real datasets are shown. TRICUT is implemented in C+ + using the Visualization Toolkit in conjunction with the RAPID and TRIANGLE libraries. The program runs under LINUX and UNIX using the MESA OpenGL library. This work gives an example of solving a complex 3D geometric problem by integrating available robust public domain software. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Evaluation of the isoflurane-sparing effects of lidocaine and fentanyl during surgery in dogs

Objective-To evaluate the isoflurane-sparing effects of lidocaine and fentanyl administered by constant rate infusion (CRI) during surgery in dogs.Design-Randomized prospective study.Animals-24 female dogs undergoing unilateral mastectomy because of mammary neoplasia.Procedures-After premedication with acepromazine and morphine and anesthetic induction with ketamine and diazepam, anesthesia in dogs (n = 8/group) was maintained with isoflurane combined with either saline (0.9% NaCl) solution (control), liclocaine (1.5 mg/kg [0.68 mg/lb], IV bolus, followed by 250 mu g/kg/min [113 mu g/lb/min], CRI), or fentanyl (5 mu g/kg [2.27 mu g/lb], IV bolus, followed by 0.5 mu g/kg/min [0.23 mu g/lb/min], CRI). Positive-pressure ventilation was used to maintain eucapnia. An anesthetist unaware of treatment, endtidal isoflurane (ETiso) concentration, and vaporizer concentrations adjusted a nonprecision vaporizer to maintain surgical depth of anesthesia. Cardiopulmonary variables and ETiso values were monitored before and after beginning surgery.Results-Heart rate was lower in the fentanyl group. Mean arterial pressure did not differ among groups after surgery commenced. In the control group, mean +/- SD ETiso values ranged from 1.16 +/- 0.35% to 1.94 +/- 0.96%. Fentanyl significantly reduced isoflurane requirements during surgical stimulation by 54% to 66%, whereas the reduction in ETiso concentration (34% to 44%) observed in the lidocaine group was not significant.Conclusions and Clinical Relevance-Administration of fentanyl resulted in greater isoflurane sparing effect than did liclocaine. However, it appeared that the low heart rate induced by fentanyl may partially offset the improvement in mean arterial pressure that would be expected with reduced isoflurane requirements.

Head, eye and arm coordination in table tennis

The aim of this study was to determine the role of head, eye and arm movements during the execution of a table tennis forehand stroke. Three-dimensional kinematic analysis of line-of-gaze, arm and ball was used to describe visual and motor behaviour. Skilled and less skilled participants returned the ball to cued right or left target areas under three levels of temporal constraint: pre-, early- and late-cue conditions. In the pre- and early-cue conditions, both high and low skill participants tracked the ball early in flight and kept gaze stable on a location in advance of the ball before ball-bat contact. Skilled participants demonstrated an earlier onset of ball tracking and recorded higher performance accuracy than less skilled counterparts. The manipulation of cue condition showed the limits of adaptation to maintain accuracy on the target. Participants were able to accommodate the constraints imposed by the early-cue condition by using a shorter quiet eye duration, earlier quiet eye offset and reduced arm velocity at contact. In the late-cue condition, modifications to gaze, head and arm movements were not sufficient to preserve accuracy. The findings highlight the functional coupling between perception and action during time-constrained, goal-directed actions.

CH3OH optically pumped by a (CO2)-C-13 laser: new laser lines and assignments

We report 12 new THz (far-infrared) laser lines from methanol (CH3OH), ranging from 58.1 mu m (5.2 THz) to 624.6 mu m (0.5 THz). A(13) CO2 laser of wide tunability (110 MHz) has been used for optical pumping, allowing access to previously unexplored spectral regions. Optoacoustic absorption spectra were used as a guide to search for new THz laser lines, which have been characterized in wavelength, polarization, offset, relative intensity, and optimum operation pressure. For 20 laser lines previously observed, we have measured the absorption offset with respect to the (CO2)-C-13 laser line center.

Optically pumped submillimeter laser lines from CD2Cl2 using a large tunability CW CO2 laser

Twenty-five new laser lines have been obtained is the wavelength region from 155 to 830 mu m by optically pumping the CD2Cl2 (deuterated dichloromethane) molecule with a CW CO3 laser having a tunability range of 300 MHz. The wavelength, polarization relative to that of CO2 pumping radiation, and offset relative to the CO2 center frequency were determined for all of the new lines and some other already known laser emissions. For all of them we give also the relative intensity and the optimum pressure of operation.

Infrared and far-infrared spectroscopy of (CH3OH)-C-13: TeraHertz laser lines and assignments

We use a (CO2)-C-13 laser as optical pumping source to search for new THz laser lines generated from (CH3OH)-C-13. Nineteen new THz laser lines (also identified as far-infrared, FIR) ranging from 42.3 mu m (7.1 THz) to 717.7 mu m (0.42 THz) are reported. They are characterized in wavelength, offset, relative polarization, relative intensity, and optimum working pressure. We have assigned eight laser lines to specific rotational energy levels in the excited state associated with the C-O stretching mode. (c) 2006 Elsevier B.V. All rights reserved.

Short-term soil CO2 emission after conventional and reduced tillage of a no-till sugar cane area in southern Brazil

The impact of tillage systems on soil CO2 emission is a complex issue as different soil types are managed in various ways, from no-till to intensive land preparation. In southern Brazil, the adoption of a new management option has arisen most recently, with no-tillage as well as no burning of crops residues left on soil surface after harvesting, especially in sugar cane areas. Although such practice has helped to restore soil carbon, the tillage impact on soil carbon loss in such areas has not been widely investigated. This study evaluated the effect of moldboard plowing followed by offset disk harrow and chisel plowing on clay oxisolCO(2) emission in a sugar cane field treated with no-tillage and high crop residues input in the last 6 years. Emissions after tillage were compared to undisturbed soil CO2 emissions during a 4-week period by using an LI-6400 system coupled to a portable soil chamber. Conventional tillage caused the highest emission during almost the whole period studied, except for the efflux immediately following tillage, when the reduced plot produced the highest peak. The lowest emissions were recorded 7 days after tillage, at the end of a dry period, when soil moisture reached its lowest rate. A linear regression between Soil CO2 effluxes and soil moisture in the no-till and conventional plots corroborate the fact that moisture, and not soil temperature, was a controlling factor. Total soil CO2 loss was huge and indicates that the adoption of reduced tillage would considerably decrease soil carbon dioxide emission in our region, particularly during the summer season and when growers leave large amounts of crop residues on the soil surface. Although it is known that crop residues are important for restoring soil carbon, our result indicates that an amount equivalent to approximately 30% of annual crop carbon residues could be transferred to the atmosphere, in a period of 4 weeks only, when conventional tillage is applied on no-tilled soils. (c) 2005 Elsevier B.V. All rights reserved.

NEW FIR LASER LINES AND FREQUENCY MEASUREMENTS FROM OPTICALLY PUMPED CD-13(3)OH-3

We report the discovery of 57 new fir laser lines from (CD3OH)-C-13 molecule optically pumped by a waveguide CO2 laser of 300 MHz tunability. For all lines, precise frequency offset measurements between the CO2 line center and the center of the absorbing (CD3OH)-C-13 line were performed using the transferred Lamb-Dip technique. We have also measured directly the frequency of seven FIR laser lines by heterodyning with already known laser lines.We present a complete list of all known laser lines (134) and frequency measurements (24) for this molecule.