Circular Movement Research Articles

Between Refusal and Refuge. Queer Feminist Bookstore Savannah Bay

Feminist bookstores have played an important role in the creation of feminist spaces since the end of the 20th century. In the Netherlands, Savannah Bay is one of the last remaining in a previous network of feminist bookstores. This article explores how the bookstore manages to uphold its function as a feminist space while operating in relative isolation. The data used for this analysis consists of a series of interviews with volunteers working at Savannah Bay. This data is analysed via Bonnie Honig’s <i>Feminist Theory of Refusal</i> (2021), which<i> </i>connects three forms of feminist resistance within one arc of feminist refusal. Crucial to this arc is the circular movement where the women first leave the city, then organise a new way of living, and then return to the city to implement their ideas. By reading the experiences of Savannah Bay volunteers via Honig’s theory of refusal, this article analyses how the bookstore manages to uphold a feminist space while being embedded in a predominantly patriarchal public sphere. It demonstrates the complex ways in which Savannah Bay continuously negotiates its relationship to the customers and volunteers it caters for on the one hand, and a patriarchal public sphere which it seeks to reform on the other hand. Additionally, this reading extends and nuances Honig’s theoretical approach by relating it to empirical data, which raises questions about the conditions for fulfilling Honig’s feminist arc of refusal, and about the relations between the various moments on the arc.

Theoretical study on the movements of bubbles

The radial and translational motions of multiple interacting spherical bubbles are obtained using classical Newton mechanics. It is seen that bubbles not only move in straight line, but also in circular motion. The tracks of the bubbles show that the interactions among them include attractive, repulsive and dynamic equilibrium. There are three types of straight line corresponding to attraction, coexistence of attraction and repulsion and dynamic equilibrium, and two types of circular movement corresponding to attraction and dynamic equilibrium. The results can provide an explanation for cavitation chain and profile in cavitation field.

Performance evaluation in die-sinking EDM of polygonal micro cavities over EN-24 alloy steel using cylindrical electrode and polygon cycle approach

The integration of advanced Electrical Discharge Machining (EDM) technology, incorporating short and electronically pulsed discharges with precise circular electrode movements, has enabled the production of intricate 3D microstructures and cavities. This paper aims to investigate the machining performance of polygonal cavities—triangular, square, pentagon, and hexagon—fabricated on steel samples using a 400 µm cylindrical copper electrode within the polygon cycle approach of EDM. Experimental investigations were conducted to assess shape error, tool wear rate, recast layer formation, and elemental characterization. Various discharge patterns and side discharges were examined to understand their effects on spark gap uniformity, tool deflection, and discharge stability. The results revealed non-uniform spark gaps, tool deflection, and corner rounding due to varying discharge patterns and side discharges. Tool wear rate was found to be directly related to polygon complexity, with higher-order polygons leading to increased wear due to extended machining durations and heat accumulation. The maximum tool wear of 7.69 × 104 µm3/s occurred in case of hexagonal cavities while in case of triangular cavities, the tool wear rate was minimum having value of 5.77 × 104 µm3/s. Scanning Electron Microscopy (SEM) examinations showed the presence of recast layers and micro-cracks, particularly in cavities with higher shape complexities. Energy Dispersive X-ray Spectroscopy (EDS) analysis identified copper deposition, local material evaporation, and foreign element accumulation on the cavity surfaces. This study provides insights into the machining performance of polygonal cavities in EDM processes. The findings underscore the influence of discharge patterns, polygon complexity, and material interactions on tool wear, surface quality, and microstructure integrity. Understanding these factors can inform optimization strategies for EDM processes, leading to enhanced precision and efficiency in microstructure fabrication.

Mundane urban (im)mobilities: work, domestic, and family lives of migrant building workers in China

ABSTRACT Interdisciplinary research from China has generated a wealth of quantitative and qualitative insights into trans-, national, regional, and local migration patterns over long and short distances through attention to diverse topics, socio-economic groups, and case-study locations. Our contribution in this paper is to advance recent critical work that is directing focus from rural-to-urban “circular movements” toward more complex spatialities and temporalities. To add value to that project, we not only engage with studies of urban (im)mobilities per se but also elaborate productive new avenues from across interdisciplinary mobilities research. Specifically, we draw on feminist, materialist, and more-than-representational thinking to highlight the contingent relatedness of migrants’ daily lives across diverse work, domestic, and family times/spaces both within and beyond cities. In doing so, we show how exploration of mundane urban (im)mobilities offers new insights to challenge binary depictions of city/countryside, home/destination, movement/stasis, belonging/marginalization, and moored/unmoordness. The conclusion signposts new research opportunities.

Deadlock prevention and multi agent path finding algorithm considering physical constraint for a massive fleet AGV system

This study introduces deadlock avoidance algorithms for Automated Guided Vehicles (AGVs) within warehouse fulfillment systems. Numerous AGVs are tasked with transporting requests to deliver shelves to workers stationed at various locations. The pathfinding challenge within such systems is identified as the Multi-Agent Pickup and Delivery (problem) and has been extensively explored in computer science and AI. Nevertheless, most prior research was conducted in environments that are discretized and allow circular movements of AGVs, potentially leading to deadlocks in real-world applications. Our proposed algorithm leverages a dynamic path block method and path reservation. Specifically, it limits movement to certain edges when AGVs navigate along reserved paths, while the remaining AGVs plan their routes using unrestricted edges. We show that our algorithm not only effectively prevents deadlocks but also scales well in environments with a high number of AGVs.

Three-dimensional video recordings: Accuracy, reliability, clinical and research guidelines - Reliability assessment of a 4D camera.

In addition to studying facial anatomy, stereophotogrammetry is an efficient diagnostic tool for assessing facial expressions through 3D video recordings. Current technology produces high-quality recordings but also generates extremely excessive data. Here, we compare various recording speeds for three standardized movements using the 3dMDface camera system, to assess its accuracy and reliability. A linear and two circular movements were performed using a 3D-printed cube mounted on a robotic arm. All movements were recorded initially at 60 fps (frames/second) and then at 30 and 15 fps. Recording accuracy was tested with best-fit superimpositions of consecutive frames of the 3D cube and calculation of the Mean Absolute Distance (MAD). The reliability of the recordings were tested with evaluation of the inter- and intra-examiner error. The accuracy of movement recordings was excellent at all speeds (60, 30 and 15 fps), with variability in MAD values consistently being less than 1 mm. The reliability of the camera recordings was excellent at all recording speeds. This study demonstrated that 3D recordings of facial expressions can be performed at 30 or even at 15 fps without significant loss of information. This considerably reduces the amount of produced data facilitating further processing and analyses.

The Pencil Exercise

Background: Voluntary posterior shoulder instability is a rare condition, with a prevalence of 0.5% to 2.6% in young adults, in which the patient is able to provoke a dislocation or subluxation through voluntary activation of the muscles. Studies have shown results that highlight the importance of abnormal cortical activation in this population and suggest physiotherapeutic treatment as first line. Indications: Currently, there are a wide range of options of physiotherapeutic treatment for this condition, such as muscle reinforcement, scapulohumeral coordination, and/or muscle activation with electrodes, all with acceptable results. Simple, low-cost neuromotor rehabilitation is based on the simplicity of a different approach. We believe that with distal-proximal neuromotor rehabilitation we can improve a physiological muscle function. Technique Description: The goal of the pencil exercise is to stimulate the cerebral cortex by making circular movements with a pen between the fingers, bridging abnormal voluntary stimulation and activation of the shoulder muscles, allowing the patient to focus, by the view, only on hand movements. Results: In this case, we have achieved the bypass of the abnormal voluntary stimulation and activation of the shoulder muscles and improve the patient's physiological shoulder function with the implementation of the pencil exercise. Conclusion: This technique may be an effective option for the treatment of voluntary posterior shoulder dislocation because it is based on the stimulation of the cerebral cortex and not on traditional physiotherapeutic or surgical interventions. It is important to note that more research is needed to validate the results of this technique and determine its long-term efficacy. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

SNI ISO/IEC 17025:2017 IMPLEMENTATION IMPACT ON TESTING LABORATORY

<p>A globally recognized standard for ensuring the competence of testing and calibration laboratories is SNI ISO/IEC 17025:2017. Many testing laboratories are currently using SNI ISO/IEC 17025:2017, and many have already received accreditation. The laboratory serves a variety of objectives, which is beneficial to enhancing the lab's performance. A laboratory's performance could be measured by how well it serves its customers and their satisfaction. This study aims to examine the impact of applying SNI ISO/IEC 17025:2017 on the number of services provided and the level of customer satisfaction in laboratories that have been accredited by KAN for the scope of CNC vertical-type milling machines and CNC lathes for position accuracy test, cutting result accuracy test, and circular movement accuracy test. This study uses a qualitative, descriptive research design and conducts elementary analysis to characterize the overall state of the data. Information on the number of services provided and the degree of customer satisfaction during 2016–2021 were compared, allowing for a comparison of the trends in service quantity and customer satisfaction. The findings indicate that the rise in laboratory services is influenced by the implementation of SNI ISO/IEC 17025:2017. Furthermore, as evidenced by a strong customer satisfaction score, the performance of the offered service has no bearing on the quantity of technological services falling under the purview of SNI ISO/IEC 17025:2017 accreditation.</p>

A Spectrotemporal EEG Mapping Approach for Decoding Imagined Marathi Language Phonemes

Individuals facing verbal communication impairments resulting from brain disorders like paralysis or autism encounter significant challenges when unable to articulate speech. This research proposes the design and development of a wearable system capable of decoding imagined speech using electroencephalogram (EEG) signals obtained during the mental process of speech generation. The system’s main objective is to offer an alternative communication method for individuals who can hear and think but face challenges in articulating their thoughts verbally. The design suggested includes user-friendliness, wearability, and comfort for seamless integration into daily life. A minimal number of electrodes are strategically placed on the scalp to minimize invasiveness. Achieving precise localization of the cortical areas responsible for generating the EEG patterns during imagined speech is vital for accurate decoding. Literature studies are utilized to determine the cortical positions associated with speech processing. Due to the inherent limitations in EEG spatial resolution, meticulous experiments are conducted to map the scalp positions onto their corresponding cortical counterparts. Specifically, we focus on identifying the scalp location over the superior temporal gyrus (T3) using the internationally recognized 10-20 electrode placement system by employing a circular periphery movement with a 2 cm distance increment. Our research involves nine subjects spanning various age groups, with the youngest being 23 and the oldest 65. Each participant undergoes ten iterations, during which they imagine six Marathi syllables. Our work contributes to the development of wearable assistive technology, enabling mute individuals to communicate effectively by translating their imagined speech into actionable commands. This innovation ultimately enhances their social participation and overall well-being.

Sensorimotor Control Using Adaptive Neuro-Fuzzy Inference for Human-Like Arm Movement

In this study, a sensorimotor controller is designed to characterize the required muscle force to enable a robotics system to perform a human-like circular movement. When the appropriate muscle internal forces are chosen, the arm end-point tracks the desired path via joint-space feedback. An objective function of the least-change rate of muscle forces is determined to find suitable feedback gains. The parameter defining the muscle force is then treated as a learning parameter through an adaptive neuro-fuzzy inference system, incorporating the rate of change of muscle forces. In experimental section, the arm motion of healthy subjects is captured using the inertial measurement unit sensors, and then the image of the drawn path is processed. The inertial measurement unit sensors detect each segment motion’s orientation using quaternions, and the image is employed to identify the exact end-point position. Experimental data on arm movement are then utilized in the control parameter computation. The proposed brain–motor control mechanism enhances motion performance, resulting in a more human-like movement.

PASTORALIST MOBILITY ALONG THE SUDANESE ETHIOPIAN BORDERLAND: TOWARDS COOPERATIVE LAND MANAGEMENT

This study followed an interdisciplinary mixed approach that consisted of social research methods and geospatial technology to investigate the livestock mobility of four pastoralist groups from Sudan and two Ethiopian pastoralist groups who fled to Sudan due to the conflict in the Tigray region. The study area is a shared borderland located between the two countries and is part of Gadarif State in Sudan and the Tigray and Amhara regions in Ethiopia. The findings of the study showed that there are diverse types of pastoral mobility in the borderland, ranging from short and circular movement to wide and directional type of mobility in response to seasonal variations, the spread of mechanised farming and the eruption of insecurity events. Despite facing numerous challenges including the governments’ restrictions on cross-border movement and the prevalence of looting and rustling, trans-boundary mobility is practised by most pastoralist groups in the borderland. Pastoralist leaders are playing an important role in facilitating cross-border mobility. The recent conflict in the Tigray region forced many Ethiopian pastoralists to flee to Sudan with their animals, and they have had to cope with this situation by reducing the number of head they own and limiting their mobility to a more confined area. Despite competing claims by both governments, there is a pressing need for a cooperative land management policy applying soft border arrangements that incorporate customary land use rights for pastoralists from both sides, instead of the hardline border policies currently in place. This article was published open access under a CC BY-NC 4.0 licence: https://creativecommons.org/licenses/by-nc/4.0/ .

How "Breast Aware" are the Indian Women? A Study among the Women Visiting a Tertiary Care, Referral, and Teaching Hospital.

"Who will educate us" lamented a School Principal after she took part in our study and education session. There is palpable low breast cancer (BC) literacy with rising incidence and disproportionate mortality rates. Breast Cancer Awareness Measure (BCAM) developed by Cancer Research UK was administered to 944 women. BCAM measures knowledge, age-related risk, and reported frequency of breast checking and other components. A woman is BC aware if she identified five or more nonlump symptoms, age-related risk, and reported breast checking once a week/month. At the end, each participant was given "Be Breast Aware" education; what/how to look for demonstrated on a model. 2.8% health professionals. 3.1% BC survivors. 78.8% had lump knowledge and 55.3% had non-lump knowledge of BC, 10% had age-related risk knowledge. 24.3% check breasts once a week/month. 41.9% aware BC is common after 50 years. 14/944 (1.5%) had BC awareness. 59.9% had breast symptoms, but never consulted a doctor, 31.1% were embarrassed, and 29.4% were scared to consult. Nearly 43% heard of breast screening, 28.4% had mammography, 26.3% had ultrasound. About 44.1% knew family history risk. Those practicing breast checking looked for a size change (24.5%), nipple position (17.4%), discharge (22.1%), pain (32.5%), and lump (24.7%) in standing (17.8%), supine (8.5%) using finger pads (15.8%) fingertips (21.6%), using circular movements (16.4%), and pinching breast tissue (19.6%). Health-care workers and BC survivors lack breast awareness which is alarming and indicates the need for BC awareness and post-BC treatment follow-up care education in these two groups and the general population. Some practice the wrong method (e.g., pinching tissue) of breast checking, which may lead to anxiety and unnecessary investigative costs. "Be Breast Aware" education based on the National Health Service 5-point plan given to 944 participants.

PENGARUH PENGUASAAN GERAK MELINGKAR BERATURAN TERHADAP HASIL BELAJAR FISIKA SISWA MATERI POKOK GRAVITASI SISWA KELAS XI SMA NEGERI 1 ANGKOLA BARAT

This research aims to find out the influence of regular circular movement to the student’s achievement is gravitation of the XI SMA Negeri 1 Angkola Barat. This research is done by usng descriptive method, it is to see the description and the experiment method of both variables.The population of this research ia all of XI SMA Negeri 1 Angkola Barat. Consist of 2 classes it is 60 students. Sampel of this research is 60 students, taken by using total sampling.Based on the calculation of pre test for score for regular circular movement is 41,78, it is fail category. Based on the calculation of post test for score for regular circular movement is 66,29, it is fail it is enough category, while the mean pre test for gravitation achievement is 44,46 it is fail category. While yhe mean post test for gravitation achievement is 68,13 it is enough category. Based on the calculation in inferensial analysis, it in pre test is found that cout is 11,25 and if it is compared to t table in 5% significant it is found 2,002. After comparing t count and t table it is got that t count is greater than t table (11,25>2,002). it in pos test is found that cout is 11,37 and if it is compared to t table in 5% significant it is found 2,002. After comparing t count and t table it is got that t count is greater than t table (11,37>2,002). The hypothesis is accepted, means that there is significant influence regular circular movement to the students achievement in gravitation of the XI SMA Negeri 1 Angkola Barat.

Cavotricuspid Isthmus-Dependent Atrial Flutter. Beyond Simple Linear Ablation.

The demonstration of a peritricuspid circular movement with a zone of slow conduction in the cavotricuspid isthmus, together with the high efficacy of linear ablation and widely accepted acute endpoints, has established typical flutter as a disease with a well-defined physiopathology and treatment. However, certain aspects regarding its deeper physiopathology, ablation targets, and methods for verifying the results remain to be clarified. While current research efforts have primarily been focused on the advancement of effective ablation techniques, it is crucial to continue exploring the intricate electrophysiological, ultrastructural, and pharmacological pathways that underlie the development of atrial flutter. This ongoing investigation is essential for the development of targeted preventive strategies that can act upon the specific mechanisms responsible for the initiation and maintenance of this arrhythmia. In this work, we will discuss less ascertained aspects alongside the most widely recognized general data, as well as the most recent or less commonly used contributions regarding the electrophysiological evaluation and ablation of typical atrial flutter. Regarding electrophysiological characteristics, one of the most intriguing findings is the presence of low voltage zones in some of these patients together with the presence of a functional, unidirectional line of block between the two vena cava. It is theorized that episodes of paroxysmal atrial fibrillation can trigger this line of block, which may then allow the onset of stable atrial flutter. Without this, the patient will either remain in atrial fibrillation or return to sinus rhythm. Another of the most important pending tasks is identifying patients at risk of developing post-ablation atrial fibrillation. Discriminating between individuals who will experience a complete arrhythmia cure and those who will develop atrial fibrillation after flutter ablation, remains essential given the important prognostic and therapeutic implications. From the initial X-ray guided linear cavotricuspid ablation, several alternatives have arisen in the last decade: electrophysiological criteria-directed point applications based on entrainment mapping, applications directed by maximum voltage criteria or by wavefront speed and maximum voltage criteria (omnipolar mapping). Electro-anatomical navigation systems offer substantial support in all three strategies. Finally, the electrophysiological techniques to confirm the success of the procedure are reviewed.

A New Picking Pattern of a Flexible Three-Fingered End-Effector for Apple Harvesting Robot

During the picking process of the apple harvesting robot, the attitude of the end effector holding the apple and the movement method of separating the apple directly affect the success rate of picking. In order to improve the stability of the picking process, reduce the gripping force, and avoid apple dislodgement and damage, this work studies the new apple-picking pattern of the flexible three-fingered end-effector based on the analysis of the existing apple-picking pattern. First, two new three-finger grasping postures for wrapping the apple horizontally and vertically on the inside of the fingers are proposed, and a new method of separating the stem with a circular-pull-down motion of the end-effector picking the apple is designed. Then, the pressure on the apple under different picking patterns was analyzed, and a branch–stem–apple simulation model was established. Combining the constraint conditions such as the angle between the apple stem and the vertical direction, the movement speed, the root impulse, and so on, the optimal angle of apple circular movement and the force required to realize the movement are obtained through dynamic simulation experiments. Finally, the experiments of apple picking patterns were carried out with the flexible three-fingered end-effector. The experiment shows that the best angle for apple picking is 15°~20° using the circular-pull-down movement separation method. In terms of average grasping force peaks and pressures, the combination of the vertical holding posture of the inner finger and the circular-pull-down movement separation method is the best picking pattern. In this pattern, the average peak exerts force on the inner side of a single finger is about 8.52 N, and the pressure is about 20.9 KPa.

Immediate effects of circular trunk movements on reach distance and centre of pressure distance during a multidirectional seated reach task in participants with post-stroke hemiparesis: a non-randomised controlled trial

Background/Aims Sitting balance training is an important therapeutic tool used by physical and occupational therapists who work with patients with hemiparesis, many of whom have difficulty shifting their weight while sitting. This study assessed the immediate effects of circular trunk movements on the maximum reach distance and the centre of pressure distance that could be achieved during a multidirectional reach task in participants with post-stroke hemiparesis and healthy individuals as a control group. Methods This non-randomised controlled study included 26 participants with hemiparesis and 10 age-matched control participants. A functional reach apparatus, body pressure distribution measuring system and digital video camera were used to measure multidirectional reach, centre of pressure trajectories and circular trunk movements. The participants completed the assessments in the following order: multidirectional reach, circular trunk movements and repeat multidirectional reach. The authors classified the centre of pressure trajectories into type A (oval) and type B (non-oval) tracings according to the shape displayed by the circular trunk movements, which corresponded to the level of trunk function. The reach distance and centre of pressure distance before and after the circular trunk movements were compared. Results The reach distance and centre of pressure distance values in the front direction of participants with hemiparesis who exhibited type A tracings and had higher trunk function were significantly greater after completing circular trunk movements. In contrast, the reach distance and centre of pressure distance values of participants in all directions who exhibited type B tracings and had lower trunk function were significantly greater after completing circular trunk movements. Conclusions Circular trunk movements appeared to affect both reach distance and centre of pressure distance, particularly in participants with hemiparesis with type B tracings and lower trunk function. Implications for practice Physical and occupational therapists could incorporate circular trunk movements into rehabilitation programmes to help individuals with post-stroke hemiparesis improve their reach distance, trunk function and ability to shift their weight while sitting.

Optimal Design of an IPMSM for HEVs Using Circular Area Movement Optimization With the Pattern Search Method

Optimal Design of an IPMSM for HEVs Using Circular Area Movement Optimization With the Pattern Search Method

Noncontact Haptic Rendering of Static Contact With Convex Surface Using Circular Movement of Ultrasound Focus on a Finger Pad.

A noncontact tactile stimulus can be presented by focusing airborne ultrasound on the human skin. Focused ultrasound has recently been reported to produce not only vibration but also static pressure sensation on the palm by modulating the sound pressure distribution at a low frequency. This finding expands the potential for tactile rendering in ultrasound haptics as static pressure sensation is perceived with a high spatial resolution. In this study, we verified that focused ultrasound can render a static pressure sensation associated with contact with a small convex surface on a finger pad. This static contact rendering enables noncontact tactile reproduction of a fine uneven surface using ultrasound. In the experiments, four ultrasound foci were simultaneously and circularly rotated on a finger pad at 5 Hz. When the orbit radius was 3 mm, vibration and focal movements were barely perceptible, and the stimulus was perceived as static pressure. Moreover, under the condition, the pressure sensation rendered a contact with a small convex surface with a radius of 2 mm. The perceived intensity of the static contact sensation was equivalent to a physical contact force of 0.24 N on average, 10.9 times the radiation force physically applied to the skin.

«Куда ж нам плыть?» Поэтика рассказа В. М. Шукшина «Чередниченко и цирк»

The article examines the features of the poetics of Shukshin’s story “Cherednichenko and the Circus”. The story is saturated to the limit with both open and veiled quotations from texts belonging to a variety of cultural spheres. The main character’s mind whimsically combines the incongruous: popular songs, arias from operas and operettas, fairy tales, Russian literary classics of the 19th century and stereotypes of Soviet ideology. Based on book samples, his plan to save the “fallen” circus performer Eva is modeled. In essence, Cherednichenko, like other heroes of Shukshin’s later works, lives not so much in the world of symbols as in the world of simulacra – signs without relation to the referent. In the artistic world of Shukshin, the spatial movements of the hero are almost always correlated with his inner, spiritual quest. Since the word “circus” comes from the Latin “circus” – circle, already in the title of the story the union “and” connects the hero not only with circus art, but also with the symbolism of circular movement: “there and back”. When trying to break out of the cycle of the usual, the Shukshin hero is immediately lost. Cherednichenko got lost, of course, not under the dome of the circus and not in the maze of alleys of the resort town. Disorientation in space is the least of his troubles. Cherednichenko’s whole life is stagnation, with rare attempts to move “at random” when he takes a step forward and takes two steps back.

The heart, a secondary organ in the control of blood circulation.

Circulation of the blood is a fundamental physiological function traditionally ascribed to the pressure-generating function of the heart. However, over the past century the 'cardiocentric' view has been challenged by August Krogh, Ernst Starling, Arthur Guyton and others, based on haemodynamic data obtained from isolated heart preparations and organ perfusion. Their research brought forth experimental evidence and phenomenological observations supporting the concept that cardiac output occurs primarily in response to the metabolic demands of the tissues. The basic tenets of Guyton's venous return model are presented and juxtaposed with their critiques. Developmental biology of the cardiovascular system shows that the blood circulates before the heart has achieved functional integrity and that its movement is intricately connected with the metabolic demands of the tissues. Long discovered, but as yet overlooked, negative interstitial pressure may play a role in assisting the flow returning to the heart. Based on these phenomena, an alternative circulation model has been proposed in which the heart functions like a hydraulic ram and maintains a dynamic equilibrium between the arterial (centrifugal) and venous (centripetal) forces which define the blood's circular movement. In this focused review we introduce some of the salient arguments in support of the proposed circulation model. Finally, we present evidence that exercising muscle blood flow is subject to local metabolic control which upholds optimal perfusion in the face of a substantive rise in muscle vascular conductance, thus lending further support to the permissive role of the heart in the overall control of blood circulation.