Maximum Reactions Research Articles

Influence of odour plume structure on upwind flight of mosquitoes towards hosts

Both the concentration and the fine-scale plume structure of host odours influence the upwind flight of female mosquitoes Aedes aegypti (L.) (Diptera: Culicidae) in a wind tunnel. The attractive effects of carbon dioxide, human skin odour and l-(+)-lactic acid were tested in homogeneous, turbulent and filamentous odour plumes. With carbon dioxide, the percentage of upwind-flying mosquitoes increased with the increasing fluctuations in concentration that occur in turbulent and filamentous plumes. In homogeneous plumes, an initial activation effect was observed, but sustained upwind flights were less frequent than in the other plumes. The opposite was found with plumes of human skin odour: the highest number of mosquitoes flew upwind in the homogeneous plume, whereas in turbulent or filamentous plumes their numbers were significantly lower. Regardless of plume type, the percentage of upwind-flying mosquitoes increased with increasing concentrations of carbon dioxide and of skin odour. With l-(+)-lactic acid, the dose-response characteristics were not consistent, and the relative effects of different plume types upon upwind flights differed within different ranges of concentration. Even maximum reactions to this compound were modest compared with those to carbon dioxide or to skin odour. Our findings demonstrate (1) that mosquitoes are able to orient upwind under continuous odour stimulation and (2) that upwind flight is dependent upon plume structure in different ways for different host odour components.

Cardiovascular reaction to job stress in middle-aged train drivers

In this study, cardiovascular (CV) response to a standard laboratory challenge was compared to 24-hr noninvasive monitoring of heart rate (HR) and blood pressure (BP) in 30 healthy middle-aged train drivers. Laboratory stress test consisted of the orthostatic test, the cold pressor test, the Valsalva maneuver, the Stroop test, and the numerical square. In addition, the participants completed an extensive questionnaire on their health state and family health history, lifestyle, job stress, social and family support, personality characteristics, and health risk behaviors. In waking activities (leisure time, traveling lo work, preparations for driving, and an uneventful driving) NR and systolic blood pressure (SBP), hut not diastolic blood pressure (DBP), were normal (e.g., mean HR = 78.3, SBP = 128.6, and DBP = 92.3 during driving). In occasional stressful work situations, most participants reacted with a considerable rise in SBP and DBP (maximum values 201 for SBP and 126 for DBP). Interindividual differences in maximum BP reactions to emergency stress were predicted reliably by several psychological characteristics and by the CV reactions to the laboratory psychological challenge. The frequency, intensity, and persistence of psychological and physiological reactions to urgent situations appear to be more relevant measures of the health impact of psychological job stress than are the shift average values of physiological stress markers.

Effects of Spatially Varying Ground Motions on Short Bridges

The effects of non-uniform excitation on short bridges were studied by computing the response of an idealized bridge to a suite of earthquake ground motions. The ground motions for each support were developed from seven measured ground motions and from idealizations of wave passage and coherency loss effects. For each set of support motions and for a range of bridge lengths and periods, the maximum support reactions were compared with the reactions calculated for coherent motions. For variable support motion, the contribution of the antisymmetric modes tended to increase, whereas the contribution of the symmetric modes generally decreased. Consequently, the dynamic component of the end support reaction computed using coherency loss excitation exceeded the response to coherent excitation for 62% of the bridges considered, varying from 75–180% of the coherent response. In contrast, the dynamic component of the central support reaction, which is affected only by symmetric modes, was unconservatively predicte...

Shear and Reaction Distributions in Continuous Skew Composite Bridges

Continuous composite steel-concrete bridges remain one of the most common types built. The proper design of new bridges and evaluation of existing ones require accurate prediction of their structural response to truck loads. North American codes of practice contain guidance for the design of right simply supported composite bridges. To design a continuous composite bridge properly, it is important to determine the maximum reactions and shears. When the bridge is skewed, the distribution of reactions and shears becomes more complicated. In this paper, the influence of skew, as well as other design parameters, on the shear and reaction distribution factors of continuous two-span composite steel-concrete bridges are investigated. Results from tests on three continuous composite steel-concrete bridge models verify the finite-element analysis for such bridges. From a parametric study, expressions for both shear and reaction distribution factors for American Association of State Highway and Transportation Officials (AASHTO) truck loading as well as for dead load are deduced. An illustrative design example is presented.

Short-term hazards of low-dose radioiodine ablation therapy in postsurgical thyroid cancer patients.

During the last two decades, there has been a trend to use low-dose I-131 ablation therapy in patients with thyroid carcinoma without metastases. However, information regarding the incidence of acute adverse reactions in patients after low-dose radioiodine therapy has not been reported. In this study, the acute radiation effects after low-dose radioiodine ablation therapy in postsurgical differentiated thyroid cancer patients was evaluated. Fifty-six patients with differentiated thyroid cancer were prospectively evaluated. None of these patients had evidence of a distant metastasis. All patients received 40 mCi (1480 MBq) I-131 MIBG orally and were evaluated for symptoms and signs by a physician on the second and seventh days after therapy. Xerostomia and nausea were the most common complaints with the same incidence rate of 5.35%. Gastralgia occurred at a frequency of 3.57%. Pain in the thyroid bed, tenderness over a parotid gland, submandibular glands, change in taste, and vomiting all were found at a frequency of 1.78%. Maximum reactions generally occurred 24-48 hours after therapy. All the symptoms except for xerostomia resolved completely in most patients within a week. In comparison with high-dose ablation therapy published in the literature, the incidence of radiation reactions in low-dose radioiodine therapy was much lower. It was concluded that in patients without lymph node or distant metastases, low-dose I-131 MIBG therapy may be recommended to avoid the high incidence of local complications after high-dose treatment.

PHOTOINDUCED REDUCTION OF CYTOCHROME c IN THE PRESENCE OF HYDROPEROXIDE DERIVATIVE OF BIPHENYL

Abstract The photosensitive hydroperoxide derivative of biphenyl (BPP) was synthesized by the ozonolysis of phenanthrene in methanol. When cytochrome c (cyt c) was illuminated by UVB light in the presence of BPP (BPPUV), it was reduced both under aerobic and anaerobic conditions. The action spectrum of the reduction was consistent with that of photolytic decomposition of BPP. Both gave maximum reactions at wavelengths around 300–310 nm. Electron spin resonance studies, using 5,5‐dimethyl‐1‐pyrroline N‐oxide as a spin‐trapping reagent, revealed the generation of hydroxyl radicals in the BPPUV system. Product analysis of adamantane oxidation by BPPW also suggested the generation of hydroxyl radicals rather than singlet oxygen. However, the effects of scavengers were complicated. Singlet oxygen scavengers significantly inhibit the reaction while none of the hydroxyl radical scavengers tested was effective in inhibiting the BPPUV‐mediated cyt c reduction. Deuterium oxide, which extends the lifetime of singlet oxygen, inhibited rather than enhanced the reaction. Reduction of cyt c was inhibited by salts, and their activities were correlated to the electron‐donating nature of the anions. These results suggest that reduction of cyt c is mediated by electron transfer from a light‐induced product of BPP, rather than by free hydroxyl radicals or singlet oxygen.

Clinical significance of cervico-ocular reactions

Cervically induced eye movements consist of a nystagmus and a deviation of the mean eye position (shift). They show in relation to different neck torsion velocities maximum reactions at slow velocities. The clinical significance of these cervico-ocular reactions is discussed controversially. Therefore we investigated 40 healthy subjects without any neurootological findings, who, in addition, underwent a manual examination. The neck torsion test was performed automatically with quantifiable stimulus parameters and a complete head fixation by means of individual dental casts. It could be shown that at a constant chair velocity of 5 degrees/s every healthy subject exhibits cervical nystagmus and/or shift deviations. In comparison a group of 30 patients with an upper cervical spine syndrome also showed similar cervico-ocular reactions without significant difference. It can be concluded that a muscle hypertonus in the deep neck region does not lead to pathological, cervically induced eye movements and that the cervical nystagmus itself is not a pathognomonic sign for cervical, proprioceptive vertigo.

Skin reactions to irritants assessed by non‐invasive bioengineering methods

Pathophysiological components of irritant contact dermatitis caused by 3 chemically-different irritants were investigated. 20 healthy volunteers were patch tested with sodium lauryl sulphate, nonanoic acid and hydrochloric acid on the flexor side of the upper arm. The skin response was evaluated after 24, 48 and 96 h by visual scoring and measured by the following bioengineering methods: transepidermal water loss measurement, electrical conductance for measurement of skin hydration, laser Doppler flowmetry for measurement of cutaneous blood flow and 20 MHz ultrasound A-scan for measurement of skin thickness. In spite of homogeneous inflammatory responses, significant differences in the severity of the injury to the skin barrier function caused by the different irritants were found. Also significant differences between irritants were found in the time course of development of maximum irritant reactions. Bioengineering methods indicating inflammatory responses (measurement of blood flow and skin thickness) were helpful in quantifying the irritant response in general, while bioengineering methods indicating epidermal damage (measurement of TEWL and electrical conductance) were helpful in classifying the individual irritants.

Kinetic and Kinematic Characteristics of 10-m Platform Performances of Elite Divers: I. Back Takeoffs

Reaction forces elicited from the 10-m platform by the 29 male and 26 female competitors in the Fifth World Diving Championships during the takeoffs for dives from the back group were analyzed and related to their patterns of motion. Major changes in linear and angular momentum occurred during the final period of upward acceleration. During this “final weighting” phase, maximum vertical reactions of 3.0 to 4.0 times body weight (BW) and maximum horizontal reactions in the “propulsive” direction of 0.5 BW were recorded. Further, the moment of vertical platform reaction with respect to the center of gravity, which was dominant and promoted backward rotation, was opposed by the moment of the horizontal component. At final contact with the platform, higher vertical velocities were more evident for back dives than multiple back somersaults, and for dives performed in tuck than in pike, and in pike than in straight positions.

Cervico-ocular eye movements in relation to different neck torsion velocities.

Rotation of the trunk with a fixed head causes isolated stimulation of cervical afferent input. Eleven patients with marked cervico-ocular reactions (COR) were selected. A neck torsion test (NTT) was performed with the help of a special apparatus. The resulting cervically induced eye movements consisted of two components. In addition to a cervical nystagmus, with its slow, compensatory phase, a deviation of the mean eye position (shift) in an anticompensatory direction, opposite to trunk rotation was observed. The COR in relation to different neck torsion velocities distinctly showed a tuning curve with maximum reactions between 4 degrees/s and 9 degrees/s. Above these values, a strong decrease in COR resulted. The optimal working range vastly differs from that of the vestibulo-ocular reflex (VOR).

Cervical afferent fibers and their relation to the regulation of equilibrium

Experiments with stimulation or denervation of cervical dorsal roots in animals have shown that input of the deep neck region is important for orientation, upright posture and the control of eye movements. Muscle spindles seem to play a dominant role as receptors for neck movements. Different ascending pathways project to the central nervous system and the signals interact with visual and vestibular stimuli. Cervical afferences provide a stabilization of the trunk during head movements because neck reflexes cancel labyrinthine reflexes. Posturographic measurements with head extension manoeuvres however did not turn out to be helpful in dizzy patients. Cervically induced eye movements are part of the complex head-eye coordination. The characteristics of cervico-ocular reactions are described. They show in relation to different neck torsion velocities a tuning curve with maximum reactions at slow velocities. Therefore the velocity of trunk rotation is, among others, an important factor when stimulating cervical afferences. The results from literature as well as own experiments show that there exists no method as yet that could yield positive evidence of cervical dizziness.

Moment Determination for Moving Load Systems

An accurate method is described for the determination of the curves of maximum moments for beams loaded with moving loads. This method avoids errors in the range of 15 percent produced by the commonly used approximation techniques. It applies to simple beams and to beams overhanging their supports. The basic idea of the method is to replace each of the moving load systems by a virtual system of stationary loads. The moments and the reactions produced by this virtual system are equal to the maximum moments and to the maximum reactions respectively produced by the actual moving system of loads. Examples of the application of the theory are given for some simple loading conditions.

The Response of Previously Irradiated Skin to Combinations of Fractionated X Radiation, Hyperthermia, and cis-Diamminedichloroplatinum

Mouse legs were irradiated with a dose of 30 Gy. After 50 days, when the acute reaction had regressed to a steady state, they were retreated with either 30 Gy of X rays delivered in six fractions over 12 days, six exposures to hyperthermia for 45 min at 42.7 degrees C, six doses of cis-DDP, or a combination of these agents. The maximum skin reactions and the skin reactions integrated over 50 days were determined. The maximum skin response was found when the previously irradiated skin was treated with a combination of X irradiation and hyperthermia. The addition of cis-DDP to this regimen did not result in a further enhancement of the skin reaction. When the second treatment was irradiation alone or cis-DDP alone, the severity of the skin reactions was similar. Injury from the initial radiation dose persisted so that the cytotoxic action of cis-DDP resulted in a level of subacute skin damage that was similar to a second course of X irradiation.

Ixodes holocyclus: Kinetics of cutaneous basophil responses in naive, and actively and passively sensitized guinea pigs

In guinea pigs, macroscopic cutaneous reactions to initial (primary) Ixodes holocyclus feeding were first apparent at 96 hr post-tick attachment, peaked at 7 days (5 mm), and were gone by Day 14. Microscopic analyses of these primary tick feeding sites at 12, 24, 48, 72, and 96 hr post-attachment revealed the dominance of mononuclear cells (63–94% of the infiltrate) at all times. Neutrophil levels were high initially (34% of the infiltrate), but quickly subsided to 6–15% of the cellular response. Eosinophils were essentially absent from primary sites, comprising only 1–3% of the infiltrate. Basophils were absent initially, but accumulated in small but significant numbers (12% of the infiltrate) at the epidermal-dermal border by 96 hr post-tick attachment, 3 days prior to maximum erythematous skin reactions. In sensitized and challenged (secondary) animals, erythematous reactions in response to secondary tick feeding were apparent as early as 18 hr post-tick attachment with peak responses at 48 hr (3–4 mm). Cutaneous leukocyte responses to challenge feedings were quantitated at 12, 24, 48, and 72 hr posttick attachment and consisted initially (12–24 hr) of a strong mononuclear cell response (72–79% of the infiltrate) that was replaced by a dominant basophil response at 48 and 72 hr. Strong cutaneous basophil responses coincided with a significant level of tick rejection. Eosinophils and neutrophils were virtually absent from these secondary responses. Other ixodid tick-guinea pig systems have a relatively stronger eosinophil response, and both basophils and eosinophils participate in immune resistance in these systems. This suggests that basophils alone mediate resistance in the I. holocyclus system. Recipients of immune serum or immune cells expressed significant cutaneous basophil responses 72 hr post-tick challenge (23 and 39% of the infiltrate, respectively). Eosinophil and neutrophil responses were weak (1–6%), whereas mononuclear cells were dominant (54–72%). Recipients of immune lymph node cells expressed a cutaneous basophilia approximately two-thirds (69%) of that observed in actively sensitized and challenged hosts, whereas immune serum recipients recruited less than one-third (31%) as many basophils. In summary, these results indicate that T-cell- and antibody-dependent mechanisms recruit infiltrates of basophils that are responsible for acquired immune resistance to I. holocyclus in guinea pigs.

Progressive Collapse of Rigid-Plastic Circular Foundations

The paper presents an analytical study of the behavior of a rigid-perfectly plastic circular foundation plate indenting an elastic two-parameter soil layer (Vlasov soil) under the action of a statically increasing applied load. Closed-form solutions are obtained for critical Loads, maximum surface settlements, foundation deflections and soil reactions in terms of the load intensity, after the plate has been transformed into a mechanism. Two distinct phases of metaplastic behavior are identified depending on whether or not full contact is maintained between soil and foundation. The results are compared with those obtained for a Winkler space and an elastic continuum halfspace.

Ultimate Behavior of Continuous Footings in Tensionless Contact with a Three-Parameter Soil

ABSTRACT The paper presents an analytical study of the behavior of rigid-perfectly plastic continuous slab foundations indenting a three-parameter soil (Kerr model) under the action of statically increasing applied line load. Simple formulas are obtained for critical loads, maximum surface settlements, foundation distortions, and soil reactions in terms of the load intensity, before and after the plate has been transformed into a mechanism. Two distinct phases of meta-plastic behavior are identified depending on whether or not full contact is maintained between soil and foundation. The results are compared with those obtained for a Winkler medium and an elastic continuum halfspace as well as with experimental data. Finally, the phenomenon of punching shear failure in the soil under the foundation perimeter is also investigated through a simple extension of the three-parameter model.

Synthesis of a coupled tumor antigen with specificity against transplanted tumors in C3H/HeJ mice.

A spontaneous mammary adenocarcinoma from a female C3H/HeJ mouse was excised, dissected into 2 mm3 pieces, and transplanted into 20 4-month-old C3H/HeJ female mice. After each tumor developed to approximately 1 cm3, they were excised, and their proteins were solubilized and extracted with hypertonic potassium chloride. The extract was purified and subsequently fractionated through a Sephadex G-200 column. The different fractions were read for absorbance on a Beckman spectrophotometer, and those fractions which represented a peak were pooled and tested for cutaneous delayed hypersensitivity on preimmunized guinea pigs. The two fractions which gave maximum hypersensitivity reactions were then coupled to human gamma-globulin. The conjugate was emulsified in Freund's complete adjuvant and used as a treatment against the proliferation of tumors transplanted in C3H/HeJ mice. 70 mice were used in this study. Animals treated with the coupled antigen had significantly smaller tumors when compared with nontreated animals.

Delayed-type skin reactions in bursectomized or thymectomized chickens.

Chickens can easily be induced to develop delayed-type skin reactions to oxazolone when animals are sensitized 7 days before the challenge. The reaction is quantitated by assessing the increase in wattle thickness: maximum reactions occur 24 h after challenge. The reaction is inhibited by neonatal thymectomy or bursectomy; these findings therefore suggest also an important B-derived component in delayed hypersensitivity to oxazolone.

Stress in Dental Patients Undergoing Routine Procedures

A method was devised to record graphically the stress that patients experience during routine dental procedures. Heart rate was used as the indicator and the variations in it showed which parts of the treatment provoked the maximum stress reactions. This pilot study indicated that by using this method it is possible to study specific dental problems and methods for treating them.

The development of lactate and malate dehydrogenases in the [formula omitted] mouse kidney

The development of lactate dehydrogenase (LDH; EC 1.1.1.27) and malate dehydrogenase (MDH; EC 1.1.1.37) was measured in the kidney of male and female C57BL 6 mice from ages prenatal 16 days to 80 days. Maximum reactions rates of the enzymes were measured in vitro by following the reduction of the nicotinamide-adenine dinucleotide spectrophotometrically. Analysis of variance showed no significant sex difference for LDH and MDH. There was a significant sex difference for the ratio LDH:MDH and a significant age difference for LDH, MDH, and the ratio LDH:MDH. In the male and female, LDH activity increased from prenatal 16 days to 30 days. Malate dehydrogenase activity reached adult values at 22 days in the male and at 30 days in the female. The ratio LDH:MDH in the male decreased from prenatal 16 days to 3 days, after which the ratio continued to decline to 20 days at a less rapid rate. This general pattern was also found in the female followed by a further decline in the ratio at 50 days. The development of LDH and MDH in the C57BL 6 mouse is tissue specific and probably parallels the development of the tissue's function. In the case of the kidney, LDH and MDH development may reflect maturation of mitochondrial function and the kidney's ability to concentrate urine.