Deviation Of Normal Research Articles

Research on Base Station Site Planning Based on Cluster Analysis and Azimuth Analysis Model

With the rapid development of the information age, the construction of 5G mobile network has improved the speed of network transmission and the utilization rate of spectrum. However, at the same time, the coverage of base stations is correspondingly less and less. In order to improve the quality of mobile communication, this paper uses the normal distribution 3-standard deviation method, Euclidean distance and 0-1 planning site selection model to analyze and divide the macro and micro base stations and make the optimal solution of site planning. Furthermore, the azimuth analysis model and K-means clustering algorithm were used to optimize the site planning and coverage area. Finally, 331 macro stations and 6459 micro base stations needed to be built, with an optimized Angle of 47 degrees and a coverage area of 93.3%. This paper provides some reference ideas for solving the problem of selecting and planning the base station site in the communication network.

A novel generating machining process for screw-rotors using an internal-cylindrical skiving cutter on a new CNC skiving machine

To reduce machining time and improve accuracy for producing screw rotors, this study proposes a generating machining process using an internal-cylindrical skiving cutter on a new CNC skiving machine. An internal-barrel rotor is first generated based on a conjugation relationship with a male/female rotor. Then, the cutting edges of the internal-cylindrical skiving cutter are defined by the intersection curves between the rake plane and the barrel rotor surface. A geometrical analysis of the clearance angle allows adjustment of the relative position between the cylindrical cutter and the skived rotor on the cutter's axis. Furthermore, a general model for the skiving process is presented. The result shows that the normal deviations on the skived screw rotors are very close to zero. In addition, a new CNC skiving machine is proposed to perform the cutting process when considering the influence of feed rate. Accordingly, the surface morphology of the skived screw rotor is in the form of micro-size waves arranged in a diagonal structure. Finally, the skived screws surface with a predefined grinding stock is achieved by modifying the cutter geometric.

Mathematical modeling on a novel manufacturing method for roller-gear cams using a whirl-machining process

The whirl-machining process is a precise, efficient, and promising machine process for manufacturing workpieces over the milling process. At the same time, the roller-gear cam has advantages over the other cam-follower system. However, the whirl-machining process has not been applied to manufacture the roller-gear cam. Therefore, this paper proposes a novel method for roller-gear cam manufacturing using a whirl-machining process. Mathematical modeling is described for generating the roller-gear cam, roller, and whirl-milling tool surface. A novel CNC machine and its coordinate system are proposed. Cutting simulations for obtaining the surface topologies and normal deviations are conducted. Globoidal cam with different cylindrical rollers, globoidal cam with a conical roller, and cylindrical cam with a conical roller are taken as case studies, and results are discussed. A virtual cutting simulation was conducted using VERICUT. Some machining examples are shown to verify the benefits of the proposed method in roller-gear cam manufacturing.

Improvement in hole-pose error for aerospace drilling applications based on Hermite surface reconstruction and manifold error similarity

Hole position accuracy and perpendicularity are significant factors in aerospace drilling. This study presents a novel compensation method with reference holes to reduce the hole position error and initial normal deviation for automated drilling systems. The hole-pose error and related generalized addition and subtraction methods are first defined using quaternions. Subsequently, approaches for accurately measuring the pose of the reference hole and calibrating the coordinate system are proposed. On this basis, the position error and initial normal error are estimated by bilinear interpolation based on the error similarity on the two-dimensional manifold, where the manifold coordinates are obtained by Hermite surface reconstruction. Subsequently, the hole-pose error is compensated for by generalized addition. For the initial normal modification, a compensation strategy utilizing the data of processed adjacent holes for interpolation was adopted. In addition, for situations in which it is inconvenient to arrange real reference holes on the product, a compensation approach employing virtual reference holes was designed. Finally, simulations and experiments are conducted, and the results demonstrate that the position error and initial normal deviation are effectively reduced by at least 42.25% and 74.68% with the proposed method, which further ensures that the indicators meet the requirements of aerospace drilling.

A model construction and measurement method for tooth surface deviation of spiral bevel gear based on a one-dimensional probe

The accurate measurement of tooth surface deviation is an important prerequisite for the quality monitoring of high-precision spiral bevel gears. A measurement method for tooth surface deviation of spiral bevel gears is proposed based on a one-dimensional probe, which can accurately measure and evaluate tooth flank. According to the forming principle of the spiral bevel gear tooth surface, the theoretical surface is constructed as the measurement reference flank. A series of measures and methods are adopted to ensure the accuracy and correctness of one-dimensional probe measurement. These effective methods include the construction of a precise positioning model of the gear blank and its surface, the measurement planning of reduction dimension which the gear needs to rotate once the normal angle after each point is measured, and the compensation for the increasing dimension of the one-dimensional probe. In addition, minimization of the normal deviation of the tooth flank is achieved by using the optimum matching technique of the theoretical and the actual surfaces. The deviation degree of the actual surface relative to the theoretical surface can be accurately calculated and evaluated by establishing a deviation model, which ensures the correctness of the evaluation result of the deviation. Finally, the test of tooth surface deviation is carried out on a JD45+ gear measuring center (GMC) using a one-dimensional probe and a Gleason 650GMS GMC using a three-dimensional probe. The measurement results show that the evaluation results of the one-dimensional probe are in good agreement with those of the three-dimensional probe. The proposed theory and method not only expand the measurement range of the GMC using a one-dimensional probe, but also have certain reference significance for the precision measurement of other complex surfaces.

Analytical formulas for the probability density of aircraft positions during flights in the piloting area

Analytical formulas for the probability densities of possible aircraft positions during flights in the piloting area are presented. Two-way exponential and normal navigation deviations of the aircraft from the selected track in the lateral direction with respect to the direction of movement in the piloting area are considered. Keywords aircraft, probability density of aircraft position, Gaussian distribution, DE distribution

Bottom-Up Clustering and Merging Strategy for Irregular Curvature Aero-Blade Surface Extraction

Surface extraction plays a significant role in blade reconstruction and measurement, improving manufacturing quality and reducing costs. Boundary extraction and region growth are the most common solutions. However, these methods treat points as complete objects and extract surfaces aggressively. Since the model and geometric constraints of the surfaces are usually blurring, these methods will lead to low accuracy results and dramatically impact the effectiveness of existing methods in practice. This paper presents a novel bottom-up irregular curvature surface extracting method called SuCMIS segmenting blade surface points from an unstructured scanning point cloud. SuCMIS applies adaptive multiple clustering methods based on the local flatness and normal deviation minimum, which improves the robustness to noise and unpredicted systematic errors. Then the curvature-based cluster merging process runs to reconstruct the blade surface. Differ to existing model-based method, SuCMIS converts surface extraction into a bottom-up process with multiply surfaces clustering and merging. It does not rely on evaluating the accuracy of the model and geometric constraints, which overcomes the natural defects of existing methods significantly. Experiments demonstrate SuCMIS’s efficiency and robustness. Compared to baseline methods, SuCMIS improves extracting accuracy with acceptable execution time, especially for complicated and large point clouds, such as blade surfaces.

A new radiological method for examining patients with forefoot deformities

The aim of the study. To establish the possibility of using the X-ray method for determining the position of the metatarsal heads for preoperative planning in the treatment of patients with forefoot deformities.Material and methods. The proposed radiological method for determining the position of the metatarsal heads includes performing radiography on a special platform. On the X-ray image, the relative position of the metatarsal heads is determined. Using the proposed X-ray method, we examined 15 patients with transient metatarsalgia under the 3rd metatarsal head, which developed after surgical treatment of hallux valgus and hammertoe (2nd toe), and 28 patients with similar forefoot deformity without postoperative metatarsalgia.Results. As a result of the proposed X-ray method, we found that in in 86.67 % of patients with transient metatarsalgia, the 3rd metatarsal head was below the adjacent 2nd and 4th metatarsal heads. In 82.14 % of patients without postoperative complications, the 3rd metatarsal head was higher or at the same level as the adjacent 4th metatarsal head. The clinical application of the proposed method made it possible to determine the position of the 2nd, 3rd or 4th metatarsal heads and to establish normal variants and deviations from the norm.Conclusions. The proposed X-ray method makes it possible to effectively determine the relative position of the metatarsal heads and to choose the optimal surgical tactics for the treatment of patients with forefoot deformities. The proposed method for determining the position of the metatarsal heads is advisable to be included in the preoperative examination along with the standard X-ray of the foot bones, due to its reproducibility, as well as the value of the information obtained.

A PROGRAM FOR CALCULATING THE PROJECTIVE RANGE AND STRAGGLING OF IONS IN A SOLIDUSING THE APPROXIMATION OF V.V. YUDIN

Ion implantation is the basis of many technological processes in electronics and microelectronics. The main quantities characterizing the penetration of ions into a solid are as follows; the length of the path of the ion until it stops completely, the average value of the projection of the total path on the direction of motion R̅p, and the average normal deviation of the projection of the path ΔR̅p. To calculate these values, computer programs SRIM, TRIM, and DYNE have been created, which require installation on a personal computer and occupy a large amount of hard disk space, which is not always justified in engineering practice. This paper describes an algorithm for a simple, installation-free program for calculating R̅p and ΔR̅p. The program algorithm is based on the Lindhard-Scharff-Schiott theory.

Numerical Simulation Analysis on Surface Quality of Aluminum Foam Sandwich Panel in Plastic Forming

The surface quality of an aluminum foam sandwich panel (AFSP) is very important for its appearance and application. This paper mainly studies the surface quality of AFSP after plastic forming. Combined with three-dimensional (3D) scanning technology, the normal deviation between the experimental AFSP and the target surface was obtained, and the surface quality parameters Sq, Sz and dmax were calculated to evaluate surface quality. The AFSP models with cubic-spherical (CS) and tetrakaidecahedral (TKD) as foam structures were established respectively. A series of numerical simulations of multi-point forming (MPF) were then carried out. Equivalent strain and deformation characteristics of spherical and saddle-shaped AFSP were discussed. The main surface defects produced by AFSP in plastic forming, such as surface wrinkle, the local straight face effect and surface dimpling were analyzed. Finally, MPF experiments were carried out, and it was found that the numerical simulation results were significantly corresponded to the experimental AFSP in terms of the degree and distribution of normal deviation and surface quality evaluation parameters. The TKD model was more consistent with the experimental results than the CS model. Moreover, the results show that the surface quality can be improved by thicker face sheets and smaller core cell sizes.

Research on Generating Gear Grinding Machining Error Based on Mapping Relationship between Grinding Wheel Surface and Tooth Flank

This paper proposes a method to study the machining error when one is generating gear grinding based on the mapping relationship between the grinding wheel surface and the tooth flank. The profile of the grinding wheel after grinding is collected, and the theoretical tooth flank is derived according to a model of generating gear grinding. By comparing the normal deviation of the theoretical tooth flank with the measured tooth flank, the machining error characteristics are identified. Firstly, the mathematical model of generating gear grinding is established according to a multi-body theory and coordinate transformation. Secondly, the experiments of the lead modification for helical gear were performed on a YW7232 CNC gear grinding machine. The tooth flank twist compensation function was turned off in experiments No. 1–No. 3, and it was turned on in experiments No. 4–No. 6, while the other process parameters kept the same. Then, the corresponding theoretical tooth flank data were derived from the grinding wheel surface which were measured using the laser profilometer LJ-V7000. Finally, the machining error characteristics were obtained by analyzing the difference between the theoretical and measured tooth flank deviations. The result of this paper can provide theoretical and practical references for the improvement of the gear grinding accuracy and gear modification design.

Determination of some Antioxidant Activities (Superoxide Dismutase, Catalase, Reduced Glutathione) and Oxidative Stress Level (Malondialdehyde Acid) in Cirrhotic Liver Patients

Objective: The aim of this study was to determine the levels of malondialdehyde (MDA) and antioxidants such as reduced glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) in the blood serum of liver cirrhosis patients.Methods: İn This investigation, we took blood from 31 healthy individuals, and 30 patients with Cirrhosis in both males and females. In this study, serum MDA levels, SOD, GSH, and CAT activities were measured spectrophotometrically. In paired group comparisons in terms of continuous variables; the T-test was utilized where normal deviation was achieved, and Mann-Whitney U statistics was utilized where it was not. In addition, ROC curve analysis was performed to evaluate their performance in differentiating the patient group from the control group.Results: SOD, CAT, and GSH activities were significantly decreased in the patient groups compared to the healthy control group (p<0.05). MDA levels were significantly higher in the patient group compared to the healthy control group (p <0.05).Conclusion: In conclusion, in this study, oxidative stress may play an important role in the development of liver cirrhosis. This study is the first one to show the relationships of MDA, SOD, CAT, and GSH in liver cirrhosis. Further studies are essential to investigate antioxidant enzymes and oxidative stress status in liver cirrhosis.

New two-step species-level AGB estimation model applied to urban parks

Aboveground biomass (AGB) estimation for urban parks has received less attention as an essential component of the global carbon cycle. Current studies focus on vast areas of natural or planted forests. The characteristics of these study areas make the use of homogenised vegetation grids (using remote sensing data) and plots (using field data) as the basic research unit a consensus. However, this data-level simplification can be significantly affected by buildings when applied to urban areas. Developing tree species identification methods based on remote sensing provides us with new ideas to explore urban AGB estimation methods at the species level. To this end, we developed a species-level AGB estimation model to address the AGB distribution in urban parks by combining multitemporal airborne light detection and ranging (LiDAR), optical remote sensing data, and field data from two urban parks in Hong Kong through a two-step strategy. First, we constructed optimal remote sensing feature-AGB mapping relationships for each sample species using sample data from the study area, the tropical allometric growth equation, and the five regression algorithms. We then explored a tree species identification method based on the annual vegetation phenological change index (AVPCI), which allowed us to quickly obtain species distribution maps for the study area. Combining these two steps allowed us to obtain AGB information for the study area based on species-level mapping relationships based on species distributions. In the model validation, the correlation between the estimated and true values of the remote sensing feature and AGB mapping relationship was 0.91, with a significantly lower normalised root mean square deviation (RMSE). The overall accuracy of the sample tree species identification was 87.5%, which was better than the results of existing studies. The final AGB obtained was also within the reasonable interval of existing studies. In addition, with the model proposed in this study, we noted that the super typhoon Mangkhut in 2018 reduced the AGB in the study area by 32.6% and demonstrated the significant underestimation of high-density urban areas in existing global biomass products. The model developed in this study addresses the problems of existing AGB estimation methods for urban vegetation represented by urban parks while effectively contributing to understanding AGB distribution and short-term carbon cycle dynamics in urban scenarios.

Life Satisfaction and Quality of Life in AML Long-Term Survivors: Primary Results of the AMLCG-Survivorship Study

Introduction An increasing proportion of patients with acute myeloid leukemia (AML) become long-term survivors (AML-LTS). Somatic and psycho-social outcomes are therefore becoming increasingly important, but little is known about the long-term effects of the disease and its treatment. Methods We designed a comprehensive analysis of AML survivorship outcomes including psycho-social well-being and somatic health status, and conducted a questionnaire-based study collecting data from long term survivors and their physicians. This report focuses on general and health-related life satisfaction (gLS/hrLS, measured by the FLZ-M questionnaire). Compared to quality of life (QoL), LS takes into consideration the subjective importance of various areas of life, and the participant's satisfaction with each. Impact of anxiety and depression, incidence of secondary cancer as well as clonal hematopoiesis are reported separately (Görlich et al, Moret et al, Krauss et al). We compared LS of AML-LTS with normative data of German adults not diagnosed with AML. Participants' FLZ-M scores were standardized relative to age- and sex-stratified normal population means and standard deviations. Results 427 former AML patients who had been enrolled in AMLCG clinical trials (AMLCG-1999/-2004/ -2008) or the AMLCG patient registry participated in this study between 5 and 18.6 years [y] after their initial AML diagnosis (median, 11.3y). Median age of AML-LTS was 61y (range 28y-93y), and 56% were female. Thirty-eight percent of participants had been treated with chemotherapy alone, while 62% received at least one allogeneic stem cell transplant (HSCT). A relapse had occurred in 24% of participants. Unexpectedly, the gLS summary score (median, .12) was significantly higher in AML-LTS (p<.001) compared to controls (median, 0), although differences were small (95%CI .03 - .32) and very likely not clinically relevant (difference and CI < 1SD). No significant difference was found for health-related life satisfaction (hrLS). Looking at LS subscales, AML-LTS reported significantly lower satisfaction with hobbies (median, -.24), fitness (median, -.18) and composure (median, -.41), but higher satisfaction with finances (median, .36), living situation (median, .10), family life (median, .37), energy (median, .04), mobility (median, .56) and independence (median, .71; all p<.003). Notably, subgroups of participants reported poor hrLS (>1SD below control mean; 17.5%) or poor gLS (13.5%), while 26% reported poor overall QoL as reported previously. All three outcomes are correlated (r=.63 to .76), with the closest association observed between QoL and hrLS (Figure A). To identify factors associated with poor LS, we fitted logistic regression models including pre-specified cofactors (age, sex, time since initial diagnosis, relapse and alloHSCT) and additional variables that associated with LS in univariate analyses. Risk of poor gLS was increased with younger age, male sex, smaller household size and income, higher depression scores and low social support (Table 1). Factors associated with poor hrLS were previous treatment with chemotherapy alone, female sex, lower number of children, high anxiety and fatigue scores, and high comorbidity burden (Table 1). Participants with higher fatigue and anxiety scores, lower social support and higher comorbidity burden reported significantly lower QoL (Table 1). No influence on QoL was found for other characteristics including treatment (HSCT vs. no HSCT), previous relapse, or AML type (p>.05). Figure A illustrates multi-dimensional associations between risk factors and psycho-social outcomes. Discussion Unlike previous studies of AML survivorship outcomes, our large cohort included a diverse spectrum of patients regarding age, time since diagnosis, and treatment modalities, which allows for new insights into long-term quality of life and life satisfaction. Our study establishes that different factors impact overall QoL and life satisfaction in AML long-term survivors. Importantly, general life satisfaction of AML long-term survivors seems not to be influenced by treatment related factors or somatic comorbidities after AML. Our data suggest AML and its treatment can have long-term psycho-social and somatic health effects, but many former patients nevertheless are satisfied with their overall life situation. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Design evaluation of disk-type milling cutter with special inserts applying analytical simulation and the experimental verification in screw rotor milling

A milling cutter with inserted blades is designed for each screw rotor since the geometry profile is unique, corresponding to its purposes and function. Correctness in cutter design, including the cutting-edge insert profile, is necessary to achieve a precise rotor profile; therefore, it is essential to introduce an enhanced cutter design. This study proposes a design of a disk-type milling cutter with special inserts. The insert cutting edge was generated on the axial plane considering the cutter curve curvature and then positioned onto the cutter body according to the modified coordinate system with a revolve angle. The analytical cutting result indicates that the simulated profile is relatively even along the gear tooth profile and the normal deviation is significantly tinier than the insert arrangement area. In addition, the cutter design applying special inserts acquires better results than standard inserts. Finally, the experimental result, including the rotor surface topography, confirms that the proposed cutter design is reliable and realistic in CNC screw rotor milling.

Dual-IDS: A bagging-based gradient boosting decision tree model for network anomaly intrusion detection system

The mission of an intrusion detection system (IDS) is to monitor network activities and assess whether or not they are malevolent. Specifically, anomaly-based IDS can discover irregular activities by discriminating between normal and anomalous deviations. Nonetheless, existing strategies for detecting anomalies generally rely on single classification models that are still incapable of reducing the false alarm rate and increasing the detection rate. This study introduces a dual ensemble model by combining two existing ensemble techniques, such as bagging and gradient boosting decision tree (GBDT). Multiple dual ensemble schemes involving various fine-tuned GBDT algorithms such as gradient boosting machine (GBM), LightGBM, CatBoost, and XGBoost, are extensively appraised using multiple publicly available data sets, such as NSL-KDD, UNSW-NB15, and HIKARI-2021. The results indicate that the proposed technique is a reasonable solution for the anomaly-based IDS task. Furthermore, we demonstrate that the combination of Bagging and GBM is superior to all alternative combination schemes. In addition, the proposed dual ensemble (e.g., Bagging-GBM) is considerably more competitive than similar techniques reported in the current literature.

Comparison of Two Scheimpflug Systems in the Measurements of Eyes with Corneal Diameter Smaller than 11.1mm.

This article aimed to evaluate the measurements of ectasia parameters by two Scheimpflug-based tomography devices, Pentacam and Sirius, for eyes with different corneal diameters (CDs). This cross-sectional research included subjects from the Fudan University EENT Hospital Refractive Center Database that were followed once a year for at least 3years with unremarkable slit-lamp examination and normal topography. Pentacam and Sirius examinations were performed on these subjects and the ectasia indices were compared between different CD groups. The right eyes of 153 subjects were included (CD ≤ 11.1mm, n = 50; 11.2-12mm, n = 52; > 12.0mm, n = 51). For the ectasia parameters from Pentacam, CD had the greatest influence on the deviation of normality of back elevation (Db, R2 = 0.371, β = -1.119, P < 0.001), overall deviation of normality (BAD-D, R2 = 0.305, β = -0.589, P < 0.001), and minimum pachymetric progression index (PPImin, R2 = 0.282, β = -0.131, P < 0.001). For parameters derived from Sirius, CD had the greatest influence on Baiocchi-Calossi-Versaci index of the back surface (BCVb, R2 = 0.138, β = -0.179, P < 0.001), keratoconus vertex of the back surface (KVb, R2 = 0.099, β = -2.273, P < 0.001), and BCV (R2 = 0.071, β = -0.078, P = 0.001). CD had little influence on surface asymmetry index of the front (SIf) and back surface (SIb), keratoconus vertex of the front surface (KVf), Baiocchi-Calossi-Versaci index of the front surface (BCVf), and Sirius classifier (P > 0.05). For Pentacam, CD mainly influenced indices related to back elevation (BE) and pachymetry progression, whereas for Sirius, CD mainly influenced indices related to BE and corneal aberration.

A novel manufacturing method for double-enveloping worms using a whirl-machining process

Double-enveloping worms (DEWs) are widely used in many applications, especially in space-saving and high-reduction ratio equipment. DEWs have a higher transmission efficiency and contact ratio than non-enveloping worms. In this study, a general method to manufacture enveloping worms using a whirl-machining process is proposed. The whirl-machining tool profile is provided from a straight-lined blade, which is tilted with an angle the same as the lead angle of the worm. The whirl-machining model is developed by a relative-motion coordinate system of a proposed CNC machining machine. The cutting simulations, surface topologies, and normal deviations for worms are demonstrated with different pitch radius of gear, lead angles, and cylindrical worms. In order to determine the practicability and accuracy of the developed model, six numerical examples are performed. A virtual cutting simulation was conducted on the worm using VERICUT. The results verify the benefits of the proposed method in DEW manufacturing.

Development and experiment of high efficiency gradient filter based on inverse problem solving method

In order to design the gradient filter for indoor air purification accurately and quickly, an inverse problem design method was proposed, and the best gradient filter meeting the design requirements was developed. The filtration performance test of the gradient filter was carried out, and the test results meet the design target value. The theoretical calculation values and test values of filtration efficiency and resistance are compared and analyzed. It is found that their theoretical calculation values and test values are within the normal deviation range, which verifies the feasibility and correctness of the inverse problem solving method.

Anaesthetic Management for Caesarian Section Complicated with Eisenmenger Syndrome Concomitant Severe Preeclampsia: A Case Report

Background: Although conception is discouraged in women with Eisenmenger syndrome, in inevitable circumstances, careful and meticulous planning of anesthesia can help the parturient survive the ordeal of a cesarean section. Anaesthetic management is aimed at avoiding haemodynamic changes that increase right-to-left shunt, thereby worsening hypoxemia. This study aimed to present a case of a pregnant woman with Eisenmenger syndrome who underwent caesarean section under general anesthesia management with severe preeclampsia.&#x0D; Case presentation: A 42-year-old pregnant woman (gravida 3, para 1, abortion 1) was admitted to our hospital at 38 weeks gestation with the chief complaint of shortness of breath and severe preeclampsia. Physical examination revealed cyanotic with clubbing fingers and elevated jugular venous pressure. Laboratory investigations did not reveal any abnormalities. Electrocardiography (ECG) shows normal sinus rhythm and right atrial deviation. General anesthesia was chosen due to obstetric complications, namely severe preeclampsia. The patient was premedicated with a gastroprotective agent, ranitidine 150 mg. At follow-up anesthesia 36 hours after surgery, the patient scored for maximum perioperative comfort and satisfaction.&#x0D; Conclusion: A multidisciplinary approach is needed to secure maternal and fetal survival for patients with Eisenmenger syndrome. Termination of Caesarean section under general anaesthesia may be the method of delivery that can be used, but care must be taken to avoid excessive and rapid blockade, dehydration, and hypoxaemia.