Slight Suction Research Articles

The evolutionary origin of human kissing.

A kiss has been a signal of special affection across continents and cultures for millennia. Between times and peoples, social norms invariably prescribe kissing to specific affiliations and contexts, implying deeper biological bases. Why the protruding of the lips and slight suction when touching another? Capuchin monkeys stick their fingers in their friends' eyes as sign of affection, why have humans developed kissing? Here I briefly review proposed hypotheses for the evolution of human kissing. Great ape social behavior suggests that kissing is likely the conserved final mouth-contact stage of a grooming bout when the groomer sucks with protruded lips the fur or skin of the groomed to latch on debris or a parasite. The hygienic relevance of grooming decreased over human evolution due to fur-loss, but shorter sessions would have predictably retained a final "kissing" stage, ultimately, remaining the only vestige of a once ritualistic behavior for signaling and strengthening social and kinship ties in an ancestral ape.

Hydromechanical behavior of unsaturated soils: Interpretation of compression curves in terms of effective stress

This state-of-the-art paper on the hydromechanical behavior of unsaturated soils focuses on the interpretation of the compression curves of unsaturated soils in terms of effective stress, with the goal of understanding the relative impacts of suction on the effective stress, net yield stress, effective yield stress and slope of the virgin compression line (VCL) during a monotonic increase in net stress. A database of compression curves was compiled for both high and low plasticity fine-grained soils under a wide range of suctions, isotropic or oedometric stress states, drainage conditions (constant suction or constant water content) and preparation techniques (impact compaction, static compaction, consolidation from slurry). Most of the compression curves plotted in terms of effective stress revealed a consistent hardening response with increasing suction and a slight suction dependency on the slope VCL. Interpretation of the compression curves in terms of effective stress led to load-collapse curves with a similar shape for a wide range of soils. Most soils evaluated had a greater rate of increase in effective yield stress with suction than the rate of increase in suction stress with suction, implying that these compacted soils may be susceptible to collapse upon wetting. Inconsistent trends were observed in some studies, which were attributed partially to natural variability but also experimental issues and limitations on the range of conditions investigated. Accordingly, recommendations are provided for future studies on the compression curves of unsaturated soils to ensure that results can be clearly interpreted in terms of effective stress.

The Inverted Heart Model for Interstitial Transudate Collection from the Isolated Rat Heart.

The present protocol describes a unique approach that enables the collection of cardiac transudate (CT) from the isolated, saline-perfused rat heart. After isolation and retrograde perfusion of the heart according to the Langendorff technique, the heart is inverted into an upside-down position and is mechanically stabilized by a balloon catheter inserted into the left ventricle. Then, a thin latex cap - previously cast to match the average size of the rat heart - is placed over the epicardial surface. The outlet of the latex cap is connected to silicon tubing, with the distal opening 10 cm below the base level of the heart, creating slight suction. CT continuously produced on the epicardial surface is collected in ice-cooled vials for further analysis. The rate of CT formation ranged from 17 to 147 µL/min (n = 14) in control and infarcted hearts, which represents 0.1-1% of the coronary venous effluent perfusate. Proteomic analysis and high performance liquid chromatography (HPLC) revealed that the collected CT contains a wide spectrum of proteins and purinergic metabolites.

Hydrodynamic and Sensory Factors Governing Response of Copepods to Simulated Predation by Balaenid Whales

Predator/prey interactions between copepods and balaenid (bowhead and right) whales were studied with controlled lab experiments using moving baleen in still water and motionless baleen in flowing water to simulate zooplankton passage toward, into, and through the balaenid oral cavity. Copepods showed a lesser escape response to baleen and to a model head simulating balaenid oral hydrodynamics than to other objects. Copepod escape response increased as water flow and body size increased and was greatest at distances ≥10 cm from baleen and at copepod density = 10,000 m−3. Data from light/dark experiments suggest that escape is based on mechanoreception, not vision. The model head captured 88% of copepods. Results support previous research showing hydrodynamic effects within a whale’s oral cavity create slight suction pressures to draw in prey or at least preclude formation of an anterior compressive bow wave that could scatter or alert prey to the presence of the approaching whale.

Dental erosion and salivary flow rate in cerebral palsy individuals with gastroesophageal reflux

A high prevalence of gastroesophageal reflux (GERD) has been observed in individuals with cerebral palsy (CP). One of the main risks for dental erosion is GERD. This study aimed to evaluate the presence of GERD, variables related to dental erosion and associated with GERD (diet consumption, gastrointestinal symptoms, bruxism), and salivary flow rate, in a group of 46 non-institutionalized CP individuals aged from 3 to 13 years. Twenty CP individuals with gastroesophageal reflux (GERDG) and 26 without gastroesophageal reflux (CG) were examined according to dental erosion criteria, drinking habits, presence of bruxism, and salivary flow rate. A face-to-face detailed questionnaire with the consumption and frequency of acid drinks, gastrointestinal symptoms (regurgitation and heart burn), and the presence of bruxism were answered by the caregivers of both groups. Unstimulated whole saliva was collected under slight suction, and salivary flow rate (ml/min) was calculated. The GERDG presented higher percentages of younger quadriplegics individuals compared to CG. The presence of regurgitation, heart burn, and tooth erosion (Grade 1) was significantly more prevalent in GERDG. It was observed difference in the salivary flow rate between the studied groups. On logistic multivariate regression analysis, the unique variable independently associated with the presence of GERD was dental erosion (P = 0.012, OR 86.64). The presence of GERD contributes significantly to dental erosion in the most compromised individuals with quadriplegics cerebral palsy individuals, increasing the risk of oral disease in this population.

Salivary osmolality and hydration status in children with cerebral palsy

Unstimulated whole salivary parameters have been identified as potential markers of hydration status. Reduced salivary flow rate and increased salivary osmolality have been shown to be useful to identify dehydration, even when minimal loss of body water occurs. This study aimed to evaluate whether unstimulated salivary flow rate and salivary osmolality from individuals with cerebral palsy correlate with plasma and urine osmolality. Thirty-five male and female children, aged 9-13 years old, diagnosed with cerebral palsy were compared to 27 nondisabled children (10-12 years old). Unstimulated whole saliva was collected under slight suction and salivary flow rate (ml/min) was calculated. Plasma without venostasis and urine were also collected. Salivary, plasma and urine osmolality were measured using a freezing point depression osmometer. Cerebral palsy children presented a reduction in salivary flow rate (50%) compared to the control group (P < 0.01). Moreover, an increase in salivary (50%), plasma (3%), and urine osmolality (20%) was also observed in the cerebral palsy children compared to the control group (P < 0.01). Salivary flow rate was negatively correlated with the salivary, plasma and urine osmolality (P < 0.01). Salivary osmolality correlated positively with plasma and urine osmolality (P < 0.01). Cerebral palsy children seem to present impaired adequate hydration status. Since the possible hypohydration condition may be reflected in saliva fluid, which could compromise the protective function exerted by saliva, the earlier this condition is identified the greater the chances of administering preventive measures. Moreover, salivary osmolality is a reliable parameter that reflects changes in plasma and urine.

Does the neuromotor abnormality type affect the salivary parameters in individuals with cerebral palsy?

Previous studies reported alterations in salivary flow rate and biochemical parameters of saliva in cerebral palsy (CP) individuals; however, none of these considered the type of neuromotor abnormality among CP individuals, thus it remains unclear whether the different anatomical and extended regions of the brain lesions responsible for the neurological damage in CP might include disruption of the regulatory mechanism of saliva secretion as part of the encephalopathy. The aim of this study was to evaluate salivary flow rate, pH and buffer capacity in saliva of individuals with CP, aged 3-16 years, with spastic neuromotor abnormality type and clinical patterns of involvement. Sixty-seven individuals with CP spasticity movement disorder, were divided in two groups according to age (3-8- and 9-16-years-old) and compared with 35 sibling volunteers with no neurological damage, divided in two groups according to age (3-8- and 9-16-years-old). Whole saliva was collected under slight suction and pH and buffer capacity were determined using a digital pH meter. Buffer capacity was measured by titration using 0.01N HCL, and flow rate was calculated in ml/min. In both age groups studied, whole saliva flow rate, pH and buffer capacity were significantly lower in the spastic CP group (P<0.05). The clinical patterns of involvement did not influence the studied parameters. These findings show that individuals with spastic cerebral palsy present lower salivary flow rate, pH and buffer capacity that can increase the risk of oral disease in this population.

Salivary osmolality in individuals with cerebral palsy

Objective To measure the salivary flow rate, osmolality, electrolyte and total protein concentrations in individuals with cerebral palsy (CP). Design Thirty-eight individuals with CP were divided according to the neuromotor abnormality type (total, spastic and dyskinectic) and compared to 22 nondisabled children (control group). Whole saliva was collected under slight suction. The salivary parameters studied were salivary flow rate, osmolality, sodium, potassium, chloride and total protein concentrations. Results CP individuals, with both neuromotor abnormality types (spastic and dyskinectic), presented an increase in salivary osmolality, total protein, potassium and chloride concentrations compared to the control group ( p < 0.05). Moreover, a reduction in salivary flow rate was verified in spastic individuals ( p < 0.05). Conclusion The reduction in salivary flow rate and increase in osmolality, total protein and electrolyte concentrations of saliva from cerebral palsy individuals could be caused by hypohydration status.

Saliva flow rate, buffer capacity, and pH of autistic individuals

The objective of the study was to evaluate saliva flow rate, buffer capacity, pH levels, and dental caries experience (DCE) in autistic individuals, comparing the results with a control group (CG). The study was performed on 25 noninstitutionalized autistic boys, divided in two groups. G1 composed of ten children, ages 3-8. G2 composed of 15 adolescents ages 9-13. The CG was composed of 25 healthy boys, randomly selected and also divided in two groups: CG3 composed of 14 children ages 4-8, and CG4 composed of 11 adolescents ages 9-14. Whole saliva was collected under slight suction, and pH and buffer capacity were determined using a digital pHmeter. Buffer capacity was measured by titration using 0.01 N HCl, and the flow rate expressed in ml/min, and the DCE was expressed by decayed, missing, and filled teeth (permanent dentition [DMFT] and primary dentition [dmft]). Data were plotted and submitted to nonparametric (Kruskal-Wallis) and parametric (Student's t test) statistical tests with a significance level less than 0.05. When comparing G1 and CG3, groups did not differ in flow rate, pH levels, buffer capacity, or DMFT. Groups G2 and CG4 differ significantly in pH (p = 0.007) and pHi = 7.0 (p = 0.001), with lower scores for G2. In autistic individuals aged 3-8 and 9-13, medicated or not, there was no significant statistical difference in flow rate, pH, and buffer capacity. The comparison of DCE among autistic children and CG children with deciduous (dmft) and mixed/permanent decayed, missing, and filled teeth (DMFT) did not show statistical difference (p = 0.743). Data suggest that autistic individuals have neither a higher flow rate nor a better buffer capacity. Similar DCE was observed in both groups studied.

Work standard for the treatment of 18th- and 19th-century iron gall ink documents with calcium phytate and calcium hydrogen carbonate

For the aqueous treatment of iron gall ink corrosion using calcium phytate and calcium hydrogen carbonate, a standardized work procedure is presented suitable for single page treatment. This standardized procedure was developed specifically for the stabilization of autograph manuscripts from the Savigny estate, that is, for German handwritten documents, letters and manuscripts from the 18th and 19th centuries. The work process involves eleven steps, of which three concern the preliminary examination and eight the actual treatment itself. The requisite materials for the implementation of this procedure, as well as for its step-by-step execution, are compiled in a systematic description for the conservation practice. The eleven steps consist of: the visual characterization of the ink (1), the testing for the iron ions (2), the test of the wettability of the object in question (3); if it is decided to pursue treatment: humidification (4), wetting (5), washing (6), the binding of free iron ions with a calcium phytate solution (7), the introduction of an alkaline buffer by means of calcium hydrogen carbonate (8), the strengthening and mechanical stabilization via a treatment using a dilute gelatin solution (9), transfer to a drying stack (10) and finally the drying of the objects under light weight (11). Individual parameters, such as the time interval between humidification and wetting, as well as the creation of a slight suction during double-screen washing can be adapted to the material properties and the condition of the objects without compromising the effectiveness of the treatment. The application of this treatment takes into account the specific material properties of for ink-corroded documents. For this reason, there is always a preliminary decision to be made, in cooperation with those responsible for the collection, either for or against an aqueous treatment. The risk that remains after such deliberation in case of an aqueous treatment is to be assessed and clearly demonstrated prior to treatment via a standardized preliminary evaluation.

Salivary parameters in infants aged 12 to 60 months with Down syndrome

The purpose of this study was to measure certain components in whole saliva from children with Down syndrome aged 12 months to 60 months. Twenty children with Down syndrome were compared with 18 children without Down syndrome. Whole saliva was collected under slight suction and the salivary pH was measured with a portable pH meter soon after collection. Electrolyte concentrations were determined by inductively coupled argon plasma with atomic emission spectrometry. Sialic acid was determined by thiobarbituric acid assay. Amylase was assayed measuring the maltose produced by the breakdown of starch and peroxidase with ortho-dianisidine. No statistically significant differences were observed in sialic acid, calcium, phosphorus and magnesium concentrations between the group with Down syndrome and the control group. Protein and sodium concentration were higher in the group with Down syndrome compared to the control group. On the other hand, the flow rate, pH, amylase and peroxidase activities and potassium concentration were lower in those with Down syndrome compared to those children in the control group.

A novel process integration, optimization and design approach for large-scale implementation of oxy-fired coal power plants with CO 2 capture

The widespread use of fossil fuels within the current energy infrastructure is considered as the largest source of anthropogenic emissions of carbon dioxide, which is largely blamed for global warming and climate change. At the current state of development, the risks and costs of non-fossil energy alternatives, such as nuclear, biomass, solar, and wind energy, are so high that they cannot replace the entire share of fossil fuels in the near future timeframe. Additionally, any rapid change towards non-fossil energy sources, even if possible, would result in large disruptions to the existing energy supply infrastructure. As an alternative, the existing and new fossil fuel-based plants can be modified or designed to be either “capture” or “capture-ready” plants in order to reduce their emission intensity through the capture and permanent storage of carbon dioxide in geological formations. This would give the coal-fired power generation units the option to sustain their operations for longer time, while meeting the stringent environmental regulations on air pollutants and carbon emissions in years to come. Currently, there are three main approaches to capturing CO 2 from the combustion of fossil fuels, namely, pre-combustion capture, post-combustion capture, and oxy-fuel combustion. Among these technology options, oxy-fuel combustion provides an elegant approach to CO 2 capture. In this approach, by replacing air with oxygen in the combustion process, a CO 2-rich flue gas stream is produced that can be readily compressed for pipeline transport and storage. In this paper, we propose a new approach that allows air to be partially used in the oxy-fired coal power plants. In this novel approach, the air can be used to carry the coal from the mills to the boiler (similar to the conventional air-fired coal power plants), while O 2 is added to the secondary recycle flow as well as directly to the combustion zone (if needed). From a practical point of view, this approach eliminates problems with the primary recycle and also lessens concerns about the air leakage into the system. At the same time, it allows the boiler and its back-end piping to operate under slight suction; this avoids the potential danger to the plant operators and equipment due to possible exposure to hot combustion gases, CO 2 and particulates. As well, by integrating oxy-fuel system components and optimizing the overall process over a wide range of operating conditions, an optimum or near-optimum design can be achieved that is both cost-effective and practical for large-scale implementation of oxy-fired coal power plants.

Hearing thresholds of a stranded infant Rissos dolphin

The underwater hearing of an infant male Rissos dolphin that stranded off the coast of southern Portugal was measured using evoked auditory potentials (AEPs). Hearing thresholds were measured from envelope following responses to amplitude modulated pure tones ranging from 4 to 150 kHz. Acoustic signals were presented within the calibrated rehabilitation pool. Evoked responses were passively gathered from human EEG electrode sensors imbedded within rubber suction cups that were gently attached to the animal with slight suction and conductor gel. One sensor was placed behind the blowhole and the other reference sensor on the back. Tones were presented 1 m directly in front of the animal under water while the animal was held in a neutrally buoyant position. Unlike the previously published audiogram for an older Rissos dolphin, the audiogram, obtained by presenting 18 different frequencies, showed that this very young animal heard tones up to 150 kHz in a manner similar to other odontocetes. These data, collected within 4 days, are the first measure of the hearing of a neonate marine mammal, verify that very young dolphins likely hear better than older animals, and show the value of using AEPs to obtain hearing thresholds of stranded animals undergoing rehabilitation.

Transport of radon gas into a tunnel at Yucca Mountain—estimating large-scale fractured tuff hydraulic properties and implications for the operation of the ventilation system

Radon gas concentrations have been monitored as part of the operation of a tunnel (the Exploratory Studies Facility—ESF) at Yucca Mountain to ensure worker safety. The objective of this study was to examine the potential use of the radon data to estimate large-scale formation properties of fractured tuffs. This objective was examined by developing a numerical model, based upon the characteristics of the ESF and the Topopah Spring welded (TSw) tuff unit, capable of predicting radon concentrations for prescribed ventilation conditions. The model was used to address two specific issues. First, it was used to estimate the permeability and porosity of the fractures in the TSw at the length scale of the ESF and extending tens of meters into the TSw, which surrounds the ESF. Second, the model was used to understand the mechanism leading to radon concentrations exceeding a specified level within the ESF. The mechanism controlling radon concentrations in the ESF is a function of atmospheric barometric fluctuations being propagated down the ESF along with ventilated air flow and the slight suction induced by the ventilation exhaust fans at the South Portal of the ESF. These pressure fluctuations are dampened in the TSw fracture continuum according to its permeability and porosity. Consequently, as the barometric pressure in the ESF drops rapidly, formation gases from the TSw are pulled into the ESF, resulting in an increase in radon concentrations. Model calibration to both radon concentrations measured in the ESF and gas-phase pressure fluctuations in the TSw yielded concurrent estimates of TSw fracture permeability and porosity of 1×10 −11 m 2 and 0.00034, respectively. The calibrated model was then used as a design tool to predict the effect of adjusting the current ventilation-system operation strategy for reducing the probability of radon gas concentrations exceeding a specified level.

Flow rate, amylase activity, and protein and sialic acid concentrations of saliva from children aged 18, 30 and 42 months attending a baby clinic

Whole-saliva samples were collected under slight suction from children enrolled in a dental-care programme at a baby clinic and analysed according to sex. The children were allocated to three age groups: 18, 30 and 42 months. No distinct sex difference was found for flow rate; there was a statistically non-significant tendency for an increased rate in females. In the males the flow rates of the 30- and 42-month groups were higher than those of the 18-month group; a similar result was obtained when findings for both sexes were combined. There was no difference in salivary protein concentration between the sexes or the age groups. Amylase activity increased significantly in males from 18 to 30 months of age. Sialic acid concentration (μmol/mg protein) showed a sex difference for the 18-month group; it was 38% higher in males than in females, and 48% higher than in the males of 42 months. This trend toward a reduction in sialic acid concentration with age suggests a reduced synthesis and secretion of glycoproteins.

Active control of cylinder wakes: use of base suction and blowing

The effects of active flow control, using base mass transpiration as control action, on the stability and dynamics of the cylinder wake at low Reynolds numbers are investigated, using numerical simulation. A spectral element method is used for the simulation. It is found that, in the subcritical Reynolds number regime (Re ‹ 47), slight suction destabilizes the wake, resulting in a vortex shedding pattern. In the supercritical regime, slight blowing stabilizes the flow, whereas high enough suction results in a steady and strongly asymmetric field. Further increase of the suction flow rate makes the flow steady and symmetric. The results are interpreted qualitatively, based on hydrodynamic stability considerations.

The heterogeneous distribution of mobile ions in the rhizosphere of acid forest soils: Facts, causes and consequences

Abstract The structure of forest soils contains chemical information relevant to the growth of the forest. Therefore, operational analysis procedures have been developed to preserve this chemical information by not homogenizing the soil sample. Under slight suction a quasi‐equilibrium is established between a circulating soil solution and the surfaces of naturally structured and homogenized soil samples. A soil structure dependent, heterogeneous distribution of water soluble basic cations is normally found in the rhizosphere of acid forest soils. Maintaining the soil structure causes a decrease in the equilibrium concentration of basic cations, especially potassium. In both naturally structured and homogenized soil samples, the exchangeable ions were determined fraction by fraction in an open percolation system. When the exchange solution is percolated under slight suction, the spontaneous exchange on both natural and artificial aggregate surfaces controls exchange with the interior of the aggregates. Agg...

Ion Channels for Communication Between and Within Cells (Nobel Lecture)

A new era in cell biology has been heralded by the prize-winning research of Erwin Neher and Bert Sakmann. These laureates measured the picoampere currents through individual ion channels (see A, below; ACh = acetylcholine). The breakthrough in suppressing the background noise was achieved by applying a slight suction to the pipette used for the current measurement. This improved the crucial pipette-to-membrane seal by two orders of magnitude. In B, below, such a “patch pipette” is shown on the end-plate membrane of denervated frog muscle fiber. Today the patch-clamp technique is used routinely with other methods such as DNA recombination or fluorimetric techniques, for example, to study the synaptic transfer in its molecular detail.

Elementary Steps in Synaptic Transmission Revealed by Currents through Single Ion Channels (Nobel Lecture)

A new era in cell biology has been heralded by the prize-winning research of Erwin Neher and Bert Sakmann. These laureates measured the picoampere currents through individual ion channels (see A, below; ACh = acetylcholine). The breakthrough in suppressing the background noise was achieved by applying a slight suction to the pipette used for the current measurement. This improved the crucial pipette-to-membrane seal by two orders of magnitude. In B, below, such a “patch pipette” is shown on the end-plate membrane of denervated frog muscle fiber. Today the patch-clamp technique is used routinely with other methods such as DNA recombination or fluorimetric techniques, for example, to study the synaptic transfer in its molecular detail.

Use of flocculants to aid the dewatering of peat

Ohinewai peat (Waikato River Valley, New Zealand) has been treated with various flocculating reagents, and the extent of flocculation has been assessed by measurements of electrophoretic mobility, specific resistance to filtration, and coefficient of compressibility of the filter cake. Of several commercial polyelectrolytes studied, Zetag 87, a highly cationic flocculant of medium molecular weight, was the most effective. Treatment with this or similar flocculants, followed by filtration under slight suction, was found to remove more than 50% of the original moisture from the peat. Such a process could be useful for preparing fuel peat in cooler climates where solar drying was not feasible. However, to be economical, the process would require a less expensive flocculant. In warmer climates where solar drying was feasible, an alternative and cheaper process using a non-ionic flocculant (Magnafloc 351) is described.