Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “vertical connectivity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1976

Measurement of gas free body volume by a diving device.

A device is presented for determination of gas free body volume, by which total body volume as well as lung volume together with intestinal gas can be measured. The measurement is performed under water. The subject to be measured keeps his head in an airfilled cylinder which allows free breathing during the measurement procedure under water. The subject sits on a seat which is connected with a vertical "probe" that is submerged in a water basin. This "body density probe" carries several measuring rods of different diameter on its upper end, which lead to an increase of buoyancy when sinking deeper into the water after additional weights have been put on the device. These rods lead to new equilibrium states which are also dependent on the compressable gas volume attached to the probe. Three equilibrium states with different added weights give a physical definition of gas free body volume, which can be calculated from a number of accurately measurable single items.

Anthropometry↗
PubMed1975

On slit-lamp microscopy.

Theoretically the contact lens with a refractive power of -64 dioptres is superior to the concave pre-set lens (Hruby lens) or the convex lens (Bayadi). In practice the results are as follows: With the convex lens the examination of the vitreous is unsatisfactory. The reversed image with the convex lens will become familiar with some experience as one will also get used to the mirror images of the three-mirror contact lens. However, the abnormal curvature of the image is really a nuisance. On the other hand the large field of view is an advantage. The convex lens is only practically useful when it can be firmly attached to the slit-lamp microscope, as otherwise the new adjustment necessary for searching the fundus is too difficult. Attachment to the microscope is also of advantage with the Hruby lens. The concave contact lens of 64 dioptres is best suited for detailed examination of vitreous and fundus and for measurements. When no value is placed on a minute examination and a quick simple orientation suffices, the concave pre-set lens (Hruby lens) has the advantage that the lens does not have to be placed on the eye. If it is centred to the middle axis of the microscope, it facilitates especially quick observation. There will be cases where the pre-set lens will be the only answer, especially shortly after an operation or with very sensitive patients. Furthermore, the Hruby lens is preferable to the Bayadi lens because the vitreous can be better examined. The Hruby lens is also advantageous for examination of the region in the middle, lateral periphery of the fundus, 30 degrees - 60 degrees, and is superior in this area to the simple concave contact lens. The Bayadi lens seems to us only indicated for fundus examination of extremely high myopes. There it definitely offers advantages over and above the concave lens. For the most peripheral fundus, expecially below and above, the three-mirror lens with its modification is so far the best method. Especially for examination of the vitreous good brightness of the slit image is required for stereoscopic examination with as large an angle as possible between microscope and illumination. The lateral parts of the most peripheral fundus cannot be examined with the vertical slit in connection with the three-mirror lens. However, this is possible with the horizontal and tilted position of the slit and intermediate positions with an oblique slit. The slit must form an angle with the microscope in order to examine vitreous and fundus in optical section. With the indentation contact lenses ciliary processes and pars plana are now accessible to slit-lamp microscopy.

Fundus Oculi↗
PubMed1991

[Anterior tooth intrusion with the base arch: preactivation by tip-back bending or curvature?].

Burstone's intrusion mechanics has been found to be effective in the treatment of a deep bite due to intrusion of the anterior teeth. The pre-activation of the intrusion arch by a tip-back bending shows a shortening in the activation. Measurements objectified the extent of the shortening and the resulting horizontal forces for TMA arches of a dimension of 0.017 x 0.025 inch relating to different distances between molars and anterior teeth and pre-activation by means of tip-back bending or curvature. The change of the vertical force in connection with a simulated intrusion of 5 mm was also registered. Clinical consequences of the therapy are discussed.

Cuspid↗
PubMed1995

The levoatriocardinal vein: morphology and echocardiographic identification of the pulmonary-systemic connection.

OBJECTIVES: This study considers the array of pulmonary-systemic connections made by the levoatriocardinal vein. The primary and associated lesions that play a role in forming this vein are examined, and echocardiography is discussed as a method for its rapid identification. BACKGROUND: The levoatriocardinal vein is a pulmonary-systemic connection that provides an alternative egress for pulmonary venous blood in left-sided obstructive lesions. It is thought to result from the persistence of anastomotic channels that connect the capillary plexus of the embryonic foregut to the cardinal veins. Only 12 cases of levoatriocardinal vein have been reported since its first description in 1926. A comprehensive description of the morphology and echocardiographic identification of this lesion has been unavailable because of its rarity. METHODS: A retrospective study was performed in 13 patients with a levoatriocardinal vein from the University of California, San Francisco. Echocardiographic findings were compared with those obtained by angiography or at necropsy. In addition, the details of 12 previously published case reports were reviewed. Age at presentation, primary obstruction to pulmonary venous return, integrity of the atrial septum and origin and drainage of the levoatriocardinal vein were compared. RESULTS: Patient age at presentation was < 2 years, with most patients presenting before age 6 months. Variations of the hypoplastic left heart syndrome accounted for the majority of primary defects encountered, although multiple but less severe left-sided lesions were seen. The atrial septum was functionally intact in most patients. The levoatriocardinal vein, defined echocardiographically, originated predominantly from the smooth-walled left atrium and drained to the superior vena cava or innominate vein; however, variations of this pattern existed. CONCLUSIONS: As a physiologic entity, the levoatriocardinal vein provides a mechanism for decompression of pulmonary venous return primarily in patients with left ventricular inflow obstruction. A levoatriocardinal vein is thought to form when the atrial septum fails to provide an alternate egress for left atrial blood. However, when a septal defect or alternative shunt occurs in conjunction with a levoatriocardinal vein, the clinical presentation may be postponed. Echocardiography provides a rapid, noninvasive modality for identifying the pulmonary-systemic connection, which may masquerade as the vertical vein in anomalous pulmonary venous connection or act as an occult source of left to right shunting in patients undergoing surgery for hypoplastic left heart syndrome.

Coronary Circulation↗
PubMed1997

Partial anomalous pulmonary venous connection: diagnosis by transesophageal echocardiography.

OBJECTIVE: This study sought to demonstrate that with proper technique, identification of the normal and abnormal pulmonary venous connection can be made with confidence using transesophageal echocardiography (TEE). BACKGROUND: Partial anomalous pulmonary venous connection (PAPVC) is an uncommon congenital anomaly whose diagnosis has classically been made using angiography. METHODS: We performed a retrospective review of all patients of all ages with PAPVC diagnosed at the Mayo Clinic who had undergone TEE because of either right ventricular volume overload or suspected intracardiac shunting by transthoracic echocardiography or intraoperatively. RESULTS: A total of 66 PAPVCs were detected in 43 patients (1.5/patient); in 2 additional patients, TEE suggested, but did not diagnose, PAPVCs. Shortness of breath was the most common presenting symptom (42.2%), followed by heart murmur and supraventricular tachycardia. Right-sided anomalous veins were identified in 35 patients (81.4%), left-sided in 7 (16.3%) and bilateral in 1 (2.3%). There was a single anomalous connecting vein in 23 patients (53.5%), two in 18 (41.9%), three in 1 (2.3%) and four in 1 (2.3%). The connecting site was the superior vena cava (SVC) in 39 veins (59.1%), right atrial-SVC junction in 6 (9.1%), right atrium in 8 (12.1%), inferior vena cava in 1 (1.5%) and the coronary sinus in 2 (3.0%). Ten anomalous left pulmonary veins were connected by a vertical vein to the innominate vein (15.1%). Sinus venosus atrial septal defect (ASD) was the most common associated anomaly in 22 patients (49%), followed by ostium secundum ASD in 6 and patent foramen ovale in 4. Fifteen patients had an intact atrial septum. Thirty-one patients (68.8%) underwent surgical repair. PAPVC was confirmed in all patients, including the two whose TEE results were suggestive of PAPVC. All 49 PAPVCs detected by TEE preoperatively were confirmed at the time of operation. CONCLUSIONS: TEE is highly diagnostic for PAPVC and can obviate angiography. Accurate anatomic diagnosis may influence the need for medical and surgical management. TEE should be performed in patients with right ventricular volume overload when the precordial examination is inconclusive.

Adult↗
PubMedDate not supplied

A robust method for evaluation of NANC transmission in human sigmoid colon muscle in vitro.

INTRODUCTION: Human tissues are notoriously difficult to work with, giving results that are quantitatively variable within and between studies. Hence, previous investigations of nonadrenergic, noncholinergic (NANC) relaxation in human colon muscle report both partial and complete inhibitions of the NANC response by specific competitive inhibitors of nitric oxide (NO) production. We have established a robust and reproducible model to examine the contribution of NO during NANC relaxation assay in human sigmoid colon muscle strips. METHODS: Complete control curves to long-train, stepwise, frequency-dependent, continuous electrical field stimulation (EFS) relaxation using vertical platinum electrodes connected to a biphasic pulse train stimulator generated NANC responses in fresh human sigmoid colon circular muscle strips set up in Bennett baths. A second complete curve was generated on the same strip in the presence of specific drugs to determine the contribution of NO to NANC relaxation. Responses to NO were also generated in muscle strips. Results were fitted to the Hill equation. RESULTS: The first and second frequency-response curves without test drugs could be fitted to the Hill equation, resulting in similar midpoint locations ([f](50)), maximal asymptotes (alpha), and midpoint slope (n) parameters. L-N(G)-nitro-arginine (L-NOARG), TTX, and haemoglobin produced a tonic contraction in the muscle strips. NANC relaxations to EFS were inhibited by L-NOARG (30-37%), TTX (56-62%), and haemoglobin (48-90%). NO relaxations were concentration dependently inhibited by haemoglobin. Haemoglobin was equipotent in mediating tonic contraction and inhibiting NO relaxation. DISCUSSION: We established reproducible assays for human colon muscle strips by the generation of two complete dose-response curves to long-train EFS, thus enabling a "within-preparations" study. The results suggest that NO contributes but is not the sole mediator of relaxations to long-train EFS in human sigmoid colon muscle. Moreover, a basal production of NO may serve to regulate tone of human colonic muscle.

Colon↗
PubMed2006

Simultaneous ejection of six electrons at a constant potential by hexakis(4-ferrocenylphenyl)benzene.

A simple synthesis of a dendritic hexaferrocenyl electron donor (5) is described in which six ferrocene moieties are connected at the vertices of the propeller of the hexaphenylbenzene core. The molecular structure of 5 is confirmed by X-ray crystallography. An electrochemical analysis along with redox titrations (which are tantamount to coulometry) confirmed that it ejects six electrons at a single potential. [structure: see text]

Journal Article↗
PubMed2006

Microfluidic vias enable nested bioarrays and autoregulatory devices in Newtonian fluids.

We report on a fundamental technological advance for multilayer polydimethylsiloxane (PDMS) microfluidics. Vertical passages (vias), connecting channels located in different layers, are fabricated monolithically, in parallel, by simple and easy means. The resulting 3D connectivity greatly expands the potential complexity of microfluidic architecture. We apply the vias to printing nested bioarrays and building autoregulatory devices. A current source is demonstrated, while a diode and a rectifier are derived; all are building blocks for analog circuitry in Newtonian fluids. We also describe microfluidic septa and their applications. Vias lay the foundation for a new generation of microfluidic devices.

Dimethylpolysiloxanes↗
PubMed2002

New aspects of the topographical anatomy of the mammary gland regarding its neurovascular supply along a regular ligamentous suspension.

The exact location of the main nerves and vessels to the breast and the nipple-areola complex has always been obscure. We found that the course of the rich neurovascular supply to the nipple runs along a regularly-located, suspensory apparatus and can therefore be predicted exactly. It consists of a horizontal fibrous septum originating at the pectoral fascia along the 5th rib, merging into vertical ligaments along the sternum medially and along the lateral border of pectoralis minor laterally. Cranially, and in an anterior direction, the vertical ligaments are connected by the superficial fascia. In the current anatomical study, we seek to demonstrate the vascular supply provided by these structures more impressively. For this purpose we dissected the ligamentous suspension after intraarterial injection with colored latex in both breasts of 10 female cadavers. The large vessels, guided by this circle of fibrous attachments could then be seen clearly. In a further 4 female cadavers, a similar procedure was performed after intraarterial injection of surgical ink. This stained the vascular layers even more intensely. This topographical knowledge has clinical relevance. The rich and constant neurovascular supply to the nipple areola complex may be maintained in a new breast-reduction technique, which allows safe postoperative viability and sensibility of the nipple. The clinical results act as a striking evidence of our anatomical findings. Further procedures taking advantage of the easy determination and access to the neurovascular supply may be seen in future.

Aged↗
PubMed2003

Total sacrectomy and reconstruction for sacral tumors.

STUDY DESIGN: Report of three patients in whom the lumbosacral junctions were successfully restored by spinal instrumentations after total sacrectomies. OBJECTIVES: To describe the surgical technique of the reconstruction of the continuity between the pelvic ring and spinal column by using a transpedicular and iliac screw system. SUMMARY OF BACKGROUND DATA: Although there have been case reports about reconstruction methods after total sacrectomy, biomechanical, and technical problems still remain unresolved. METHODS: Total sacrectomy was carried out in three cases: two with chordomas and one with a recurrent giant cell tumor. In the first case, reconstruction was achieved with Zielke transpedicular screw and rod system and a sacral rod. The other two patients were reconstructed using a transpedicular and iliac screw system and a sacral rod for bilateral fixation of the iliac wings. In the third patient, the vertical rods were connected to transverse rod with rod connectors. RESULTS: No instrumentation failure was observed, and the continuity between the pelvic wing and spinal column was established with the instrumentation and bone grafting. Although one patient died of metastatic chordoma, the lumbosacral junction was successfully reconstructed with the instrumentation. The other two patients could stand with double crutches 13 and 2 years after surgery, respectively. CONCLUSIONS: Total sacrectomy is a feasible operation for primary malignant tumors involving the entire sacrum. Reconstruction of the union between the lumbar spine and the ilia with spinal instrumentation achieves stabilization suitable for ambulation.

Adult↗
PubMed2004

Fast algorithm for detecting community structure in networks.

Many networks display community structure--groups of vertices within which connections are dense but between which they are sparser--and sensitive computer algorithms have in recent years been developed for detecting this structure. These algorithms, however, are computationally demanding, which limits their application to small networks. Here we describe an algorithm which gives excellent results when tested on both computer-generated and real-world networks and is much faster, typically thousands of times faster, than previous algorithms. We give several example applications, including one to a collaboration network of more than 50,000 physicists.

Journal Article↗
PubMed2004

Optimizing transport in a homogeneous network.

Many situations in physics, biology, and engineering consist of the transport of some physical quantity through a network of narrow channels. The ability of a network to transport such a quantity in every direction can be described by the average conductivity associated with it. When the flow through each channel is conserved and derives from a potential function, we show that there exists an upper bound of the average conductivity and explicitly give the expression for this upper bound as a function of the channel permeability and channel length distributions. Moreover, we express the necessary and sufficient conditions on the network structure to maximize the average conductivity. These conditions are found to be independent of the connectivity of the vertices.

Journal Article↗
PubMed2001

A simple isohedral tiling of three-dimensional space by infinite tiles and with symmetry Ia(-)3d.

A tiling of space by tiles that have all hexagonal faces and are infinite in one direction is described. The tiling is simple (four tiles meet at each vertex, three at each edge and two at each face) and carries a 4-connected net whose vertices are the lattice complex S* with symmetry Ia(-)3d. The tiling is closely related to the densest cubic cylinder packing, Gamma. It is shown that the other invariant cubic lattice complexes unique to Ia(-)3d (Y** and V*) are also related to the same cylinder packing.

Journal Article↗
PubMed2000

Bone response to implant-supported frameworks with differing degrees of misfit preload: in vivo study in rabbits.

PURPOSE: To study the bone response around implants placed in tibia of rabbits that supported misfitting superstructures secured with different degrees of preload. MATERIALS AND METHODS: Twelve rabbits were provided with two terminal 10-mm and one intermediate 7-mm-long implant in each tibia. After an integration time of about 9 weeks, nine of the animals received one control framework each (n = 9), designed with good fit to all three implants. In the other tibia of these animals, and in both tibias in the remaining three rabbits, test frameworks (n = 15) were connected with a vertical misfit of about 1 mm to the intermediate implant. The intermediate set screws were tightened with a torque ranging from 15 Ncm to 26 Ncm in the different test frameworks. The fascia and skin was then sutured back over the implants. After a loading period of 2 to 3 weeks, the animals were sacrificed, and histomorphometric measurements were made and correlated to the different levels of preload of the central implant. RESULTS: The mean bone-to-metal contact for the three best consecutive threads of the central implant was 40% for both test and control sites (p > .05). Compared to the other regions of the implant thread, less bone-to-metal contact was found at the tip of the test implant threads in the low preload group (p < .05). However, the same relation was not observed in the high preload group. A significant correlation was observed between increasing degree of preload in the central screw joint and increasing bone-to-metal contact, most obviously noticed at the tip of the implant thread (p < .01). CONCLUSIONS: Misfit stress levels of clinical magnitudes do not seem to jeopardize osseointegration per se. On the contrary, clinical levels of preload stress seem to significantly promote bone remodeling at the tip of the implant thread.

Animals↗
PubMed1989

Low bone mass may not be the only cause of skeletal fragility in osteoporosis.

Skeletal fragility in postmenopausal osteoporosis is not due solely to reduction in bone mass. This fact explains some of the overlap in bone mineral measurements observed between patients who are fracturing and age- and sex-matched normals who are not. Changes in skeletal architecture and bone remodeling occur with age which can account for some of the fragility. These changes are exaggerated in patients with postmenopausal osteoporosis who are suffering spine fractures. Three abnormalities have been described by histomorphometric methods which can account for skeletal fragility out of proportion to the degree of bone loss. They are: (i) loss of trabecular connectivity such that vertical weight-bearing bars lose their cross-attachments with each other, thus becoming susceptible to buckling; (ii) inefficient and prolonged microdamage repair due to periods of pause in the formation phase of remodeling; and (iii) accumulation of unrepaired microdamage in unremodeled bone tissue in the central part of trabeculae due to reduced osteon wall thickness coupled with maintenance of trabecular thickness. Recognition of these abnormalities should broaden our approach to the study of skeletal fragility in the syndrome of postmenopausal osteoporosis.

Biomechanical Phenomena↗
PubMed1998

The mean-integral representation of rectangles.

To assess perceptual interaction between the height and width of rectangles, we used an accuracy variant of the Garner paradigm. We measured the discriminability of height and width (baseline tasks) and size and shape (correlated tasks). From the d' values in these conditions, we estimated perceptual distances and inferred a mean-integral representation in which height and width corresponded to non-independent dimensions in a perceptual space. This model accounted well for performance in these two-stimulus conditions, and it also explained 70%-80% of the decline in performance in selective and divided attention. In a second experiment, conducted for purposes of comparison with the rectangle discrimination Experiment, we studied the discrimination of horizontal and vertical line segments connected in an L-shape. In size discrimination, observers were equally good with line pairs and rectangles, suggesting holistic perception; but in shape discrimination, they appeared to combine information from the two line-pair components of the rectangle independently. The mean-integral model was again successful in relating performance in the Garner tasks quantitatively.

Adult↗
PubMed2000

The nuclear pore complex: structure, function, and dynamics.

A full understanding of nucleocytoplasmic transport depends on knowledge of nuclear pore complex (NPC) structure, the functional roles of NPC components, their interactions during transport and dynamics during the cell cycle. NPC structure is conserved, flexible, and is not simply a tunnel between the nucleus and cytoplasm but appears to be actively involved in the transport process by a series of structural modifications. Transport through the NPC begins in either of its asymmetrical peripheral compartments that are both structurally reorganized during transport in different ways. The central compartment is composed of two symmetrical halves, and functions as a system of transiently open, discrete gates that is not believed to play a role in determining direction. Each NPC subunit has a specific morphology that corresponds to the functional role it plays. A complicated system of vertical and horizontal connections may allow one part of the NPC to transmit a signal to other parts, leading to an ordered series of conformational changes that drive translocation. High-resolution scanning electron microscopy has identified sequential stages of NPC assembly in vitro and revealed how the individual NPC components are assembled into a mature NPC. This review focuses on structural events during transport and on possible mechanisms of NPC assembly.

Animals↗
PubMed2004

China's public health-care system: facing the challenges.

The severe acute respiratory syndrome (SARS) crisis in China revealed not only the failures of the Chinese health-care system but also some fundamental structural deficiencies. A decentralized and fragmented health system, such as the one found in China, is not well-suited to making a rapid and coordinated response to public health emergencies. The commercial orientation of the health sector on the supply-side and lack of health insurance coverage on the demand-side further exacerbate the problems of the under-provision of public services, such as health surveillance and preventive care. For the past 25 years, the Chinese Government has kept economic development at the top of the policy agenda at the expense of public health, especially in terms of access to health care for the 800 million people living in rural areas. A significant increase in government investment in the public health infrastructure, though long overdue, is not sufficient to solve the problems of the health-care system. China needs to reorganize its public health system by strengthening both the vertical and horizontal connections between its various public health organizations. China's recent policy of establishing a matching-fund financed rural health insurance system presents an exciting opportunity to improve people's access to health care.

Capitalism↗