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PubMed1989

Spacing in the human deciduous dentition in relation to tooth size and dental arch size.

Dental casts of 243 preschool children, 129 males and 114 females, aged 2.5-5.5 years, were analysed for the presence of interdental spaces, mesiodistal crown diameters, intercanine width, intermolar width and arch length (circumference). The prevalence of primate spaces (diastemata mesial to the upper canines and distal to the lowers) varied from 65 to 90% by arch and sex; it was lowest in the lower arch especially in females, and highest in the upper. These prevalences did not increase with age; however, other spaces which usually occur between incisors may develop towards the end of the deciduous dentition, commonly in arches with primate spaces. Generally, spacing of the deciduous anterior teeth was significantly related to mesiodistal crown diameter and intercanine arch width. The crowns were significantly broader and the arches significantly narrower in cases with no spaces than in those where spaces existed. As the genetic programming for tooth size also normally affects arch size, greater discrepancies between mesiodistal crown diameters of the deciduous anterior teeth and their permanent successors are probably associated with more deciduous arch spacing.

Age Factors↗
PubMed1994

Effect of increasing cement space on cementation of artificial crowns.

In this study, the effect of cement space on cementation with an artificial crown and machined die was investigated. Spacing was varied in increments of 10 microns, and the dies were cemented in the crown by a force of 25 N with either zinc phosphate cement or a silicone fluid. Separation of the artificial crown and die was measured relative to complete seating without cement. A silicone fluid of 10.6 Pa seconds viscosity was used first with seating times from 168 seconds (SD 8.8 seconds) with no spacing to 2.1 seconds (SD 0.07 second) with 50 microns spacing. Unless 40 microns of spacing was used, the zinc phosphate cement did not allow the artificial crown to seat to less than 30 microns seating discrepancy, and it was suggested that particles in the cement caused this effect. The seating discrepancy ranged from 368 microns (SD 10 microns) without spacing to 29 microns (SD 1 micron) with 50 microns spacing. It was concluded that providing cement space substantially facilitated seating of crowns during cementation.

Cementation↗
PubMed1986

Characterization of filaments within the subacrosomal space of rat spermatids during spermiogenesis.

Two types of filaments were observed within the subacrosomal space of rat spermatids. The first of these types was characterized as actin by demonstration of actin filament affinity for myosin S-1 subfragments. Actin filaments were noted in the subacrosomal space shortly after the acrosomal sac made contact with the nucleus. As the acrosome increased its surface area contact with the spermatid nucleus, the number of layers of subacrosomal filaments increased. Pre-treatment with detergent, which in addition to permeablizing cells to allow entry of S-1, also caused the acrosome to vesiculate and the subacrosomal space to widen. In such preparations filaments were more easily visualized and appeared to extend between the nuclear and acrosomal membranes, indicating, but not proving, attachment to these membranes. During spermatid clongation, the number of actin filaments in the subacrosomal space increased greatly, especially over the dorsal convex region of the spermatid head. The polarity of the majority of filaments was not ascertainable since filaments were tightly packed within the narrow subacrosomal space. In late spermiogenesis (steps 18 and 19), actin filaments were no longer detected within the subacrosomal space. A second and much thicker type of filamentous structure was observed in the subacrosomal space of spermatids at steps 14-17 of spermiogenesis. About 14 nm in diameter (10-15 nm measurement range depending on fixation protocol utilized), these filaments did not decorate with myosin S-1 subfragments and were found in subacrosomal regions not containing actin. Fourteen nanometer filaments were seen in parallel array along the ventral folded portion of the nuclear membrane and extended partially around the nucleus. Like actin filaments. 14 nm filaments were not seen in the subacrosomal space during late spermiogenesis.

Acrosome↗
PubMed2006

k-space inherited parallel acquisition (KIPA): application on dynamic magnetic resonance imaging thermometry.

In this study, a novel method for dynamic parallel image acquisition and reconstruction is presented. In this method, called k-space inherited parallel acquisition (KIPA), localized reconstruction coefficients are used to achieve higher reduction factors, and lower noise and artifact levels compared to that of generalized autocalibrating partially parallel acquisition (GRAPPA) reconstruction. In KIPA, the full k-space for the first frame and the partial k-space for later frames are required to reconstruct a whole series of images. Reconstruction coefficients calculated for different segments of k-space from the first frame data set are used to estimate missing k-space lines in corresponding k-space segments of other frames. The local determination of KIPA reconstruction coefficients is essential to adjusting them according to the local signal-to-noise ratio characteristics of k-space data. The proposed algorithm is applicable to dynamic imaging with arbitrary k-space sampling trajectories. Simulations of magnetic resonance thermometry using the KIPA method with a reduction factor of 6 and using dynamic imaging studies of human subjects with reduction factors of 4 and 6 have been performed to prove the feasibility of our method and to show apparent improvement in image quality in comparison with GRAPPA for dynamic imaging.

Algorithms↗
PubMed1998

Pleural space irrigation and modified Clagett procedure for the treatment of early postpneumonectomy empyema.

OBJECTIVE: The incidence of postpneumonectomy empyema is 5% to 10%. Approximately half of postpneumonectomy empyemas occur within 4 weeks of pneumonectomy. A bronchopleural fistula is found in more than 80% of the patients. The classic treatment of postpneumonectomy empyema includes parenteral antibiotics, drainage of the pleural space, removal of necrotic tissue, and open pleural packing for many weeks followed by obliteration of the empyema space with antibiotic fluid or muscle. This approach results in prolonged hospitalization, repeated operations, and significant morbidity. As a possible means of decreasing morbidity with the classic treatment of postpneumonectomy empyema, we studied the use of pleural space irrigation in these patients. METHOD: In a 5-year period, we treated 22 patients with early postpneumonectomy empyema. All patients had a bronchopleural fistula. All patients underwent emergency drainage of the pleural space followed by thoracotomy, debridement of necrotic tissue, closure of the bronchial stump with absorbable monofilament suture, and pleural space irrigation. After a negative Gram stain from the pleural fluid, the pleural space was filled with 2 L of debridement antibiotic solution (DAB solution) (gentamicin 80 mg/L, neomycin 500 mg/L, and polymyxin B 100 mg/L), and the irrigation and drainage catheters were removed. RESULTS: Twenty patients had negative Gram stains on day 9, and 2 patients had a negative Gram stain on day 16. The mean duration of hospitalization was 12.9 +/- 3. 4 days. There was no recurrence of empyema or a bronchopleural fistula. CONCLUSIONS: Pleural space irrigation followed by obliteration of the pleural space with an antibiotic solution required one surgical procedure and resulted in significantly shorter hospitalization and decreased morbidity in patients with early postpneumonectomy empyema.

Anti-Bacterial Agents↗
PubMed2001

Influence of vertical panels on use of space by domestic fowl.

In the wild, cover is used by animals to seek shelter from the elements, protection from predators and aggressive conspecifics and as a way to reduce inter-animal communication. Rearing environments for captive raised fowl often contain open areas that are lacking in complexity and that are greatly underused. As a result, use of space within pen-type enclosures is often not uniform. This paper investigates the effect of increased environmental complexity on the use of space by broilers. The experiment consisted of three cover treatments (mesh panels, frame panels and no cover) and three group sizes (80, 110 and 140). The vertical panels, constructed of PVC piping, were positioned in pen centers, while the pen centers in the no cover treatment were left empty. It was hypothesized that the provision of vertical panels to pen centers would attract birds into the central space and would lead to a more uniform distribution of birds. Using a grid-coordinate system set up in each pen, scan samples were taken on the use of space in each pen four times per day, 3 days per week from 5 to 44 days of age. Use of space in the central region for the two cover treatments was significantly higher than for the no cover treatment (P<0.0001). The effect of cover treatment on the mean percentage of birds using the central space was influenced by age (P<0.0001) and by group size (P<0.05). Differences in the use of space between the frame and mesh treatment were only found during week 1. In the side, end and middle regions surrounding the panels, use of space was influenced by cover treatment and age (P<0.0001). Over 80% of the use of pen center occurred at the ends and sides of the panels. These results support the hypothesis that the presence of vertical panels results in a more uniform distribution of birds within the pen by increasing the number of birds using the center.

Journal Article↗
PubMed1996

Radiographic assessment of the trapezial space before and after ligament reconstruction and tendon interposition arthroplasty.

A radiographic method was developed, the trapezial space ratio, for assessing the space occupied by the trapezium (a space defined by the distal scaphoid and thumb metacarpal base divided by the thumb proximal phalanx). This method was applied to 100 normal thumb radiographs and to the radiographs of 15 patients with symptomatic degenerative arthrosis of the thumb basal joint before and after operative treatment with ligamentous reconstruction and tendon interposition arthroplasty. The trapezial space ratio averaged 0.476 +/- 0.033 for radiographs of normal thumbs, 0.372 +/- 0.084 for the pre-operative radiographs of thumbs with symptomatic basal joint arthrosis, and 0.270 +/- 0.078 for the radiographs of thumbs following basal joint arthroplasty. A significant reduction in the trapezial space ratio was noted when values from arthritic thumbs were compared to those of normal thumbs (22%; P < 0.0001). A further reduction in the trapezial space ratio was noted when post-operative values were compared to pre-operative ones (27%; P < 0.0002). Comparing post-operative trapezial space ratio values to values obtained in normal thumbs, a reduction of 43% was found in those thumbs treated operatively. These finding indicate that the trapezial space is reduced significantly in thumbs with severe degenerative arthrosis compared to normal thumbs and that ligament construction tendon interposition arthroplasty is not entirely successful in either restoring or maintaining the length of the thumb ray.

Adult↗
PubMed1997

Prussak's space: chronological development and routes of aeration.

Investigation of Prussak's space and its relationship to adjacent spaces is important in elucidating the cause of retraction pocket and cholesteatoma formation in this space. This study was designed to quantitatively characterize the chronological development of Prussak's space and its relationship to adjacent spaces in temporal bones. One-hundred and forty-nine human temporal bone slides (115 normal, 28 with otitis media with effusion, three with retraction pockets and three with attic type cholesteatoma) including specimens ranging from fetal to adult bones were studied. Prussak's space was formed and sufficient aeration routes established by 4 years of age in normal temporal bones. In temporal bones with otitis media with effusion, however, the growth of Prussak's space was suppressed and few routes for aeration established until 10 years of age. In normal temporal bones, Prussak's space developed with aeration routes sufficient to avert the negative pressure which can result in retraction pocket formation in the pars flaccida of the tympanic membrane.

Adolescent↗
PubMed2002

The cricothyroid space: a guide for successful thyroidectomy.

OBJECTIVE: The frequent complications of thyroid surgery are mostly related to the anatomy of the region. This stimulated us to look for a starting point that makes exploration of the region easier and consequently reduces complications. We aimed to explore and define the anatomy of the cricothyroid [CT] region from cadaveric dissection and to present the outcome of 73 consecutive thyroidectomies starting from a space in the CT region. METHODS: Dissection in the thyroid gland region and creating a space in the CT region was performed on five cadavers [10 spaces], followed by 73 consecutive thyroidectomies through a standard approach beginning from the CT space. RESULTS: In all cadavers, a space was easily created in the CT region. Vessels, nerves and the parathyroid glands were identified. Standard thyroidectomy starting from the CT space was performed on 73 patients. The external laryngeal nerve was seen in 40% of the cases. The recurrent laryngeal nerve was identified and preserved in all patients. Six patients had temporary hypocalcaemia and eight had a temporary voice change. None of the patients had permanent hypoparathyroidism or recurrent laryngeal nerve palsy. CONCLUSION: The CT space is an avascular space medial to the thyroid lobe and is a good starting point for thyroidectomy that allows easy and safe exploration of the region.

Adult↗
PubMed1997

The effects of position on the radiographic joint space in osteoarthritis of the hip.

The aim of the study was to assess whether radiographic hip joint space thickness was changed by weight-bearing (WB) compared with non weight-bearing (NWB) position, and to evaluate whether radiographs centered on the hip were more sensitive than pelvic X-rays to detect such a change. Anteroposterior radiographs of the pelvis were made in 30 patients with hip osteoarthritis OA (46 OA and 11 normal hips). Osteoarthritic, as well as contralateral normal hips were analyzed. Radiographs centered on OA hip were performed in 28 other patients. X-rays were made in WB and NWB positions using a standardized radiological procedure. Measurements of mean joint space width (MeanJSW) maximum joint space narrowing (MaxJSN) and joint space surface area (JSA), were made using a computerized image analysis system. The joint space width was unaffected by WB in normal joints but decreased with WB in OA joints. The decrease was significant only when considering MaxJSN in patients with a joint space thickness smaller than 2.5mm. The difference between WB and NWB was larger in radiographs centered on the hip than on pelvic X-rays. MeanJSW and JSA were found to be less sensitive than MaxJSN. The decrease of joint space width was inversely correlated with joint space size in WB. These results suggest that WB radiographs of the hip should be used in preference to NWB in studies of hip OA.

Aged↗
PubMed2005

Determinants of spacing contraceptive use among couples in Mumbai: a male perspective.

This study aimed to determine the factors influencing the use of spacing contraceptive methods in India, particularly from men's perspective. Data were obtained through a semi-structured interview schedule from 2,687 married men aged between 18 and 40 years from central Mumbai City, India, during 1999. Chi-squared tests and binary logistic regression analysis was carried out to determine the relationship between various variables and the likelihood of a couple using spacing contraceptive methods. Of the 2,687 couples, 1,395 (51.9%) were using one or other method of spacing contraceptives and 1,292 (48.1%) were not using any method at the time of survey. Male participation in contraceptive use was 23% (condom and withdrawal). The results indicate that the use of spacing contraceptive methods was significantly higher among those couples where the men desired one or two children (OR=4.3), had knowledge of five or more contraceptive methods (OR=1.9) and discussed with their wives obtaining family planning information (OR=3.2), spacing (OR=2.7) and permanent (OR=2) contraceptive methods. Age, income, desired number of children, knowledge of a greater number of contraceptive methods, inter-spouse communication regarding obtaining family planning information, spacing and permanent methods were found to be strong predictors of the use of spacing contraceptive methods. The study underlines the importance of intervention programmes aimed at promoting a small family norm, increasing the number of contraceptive choices available and encouraging inter-spouse communication. Hence, policymakers and programme managers should encourage interventions in this direction, targeting couples to enhance the use of spacing contraceptive methods.

Adolescent↗
PubMed2004

Combined epidural/spinal anaesthesia: needle-through-needle or separate spaces?

BACKGROUND AND OBJECTIVE: This prospective, randomized and blinded study compared the performance of a new needle-through-needle (NTN) kit (Epistar; Medimex, Germany) with the double-space technique for providing combined spinal epidural anaesthesia during Caesarean section. METHODS: Following local Ethics Committee approval and patient consent, 200 females were randomized to receive combined spinal epidural anaesthesia by the double-space (n = 100) or NTN (n = 100) technique. The frequency with which the intrathecal component could achieve a T5 block to touch for Caesarean section without the need for epidural augmentation or an alternative technique was determined. The time from start of procedure to achieving a block height to T5 was recorded. Pain and backache at insertion, and at 24 h follow-up were recorded using a visual analogue scale. To remove any bias due to posture, 50% of each group were further randomized to receive their block in the sitting or in the left lateral position. To evaluate improvement of performance over time the success in the first 100 study patients were compared to the success in the second 100. RESULTS: A successful block to T5 with the double-space and NTN techniques were 80 vs. 54, odds ratio 0.29. Failure to enter the intrathecal space once the epidural space had been located occurred in 29 patients in the NTN group. Time to readiness for surgery was 15 min (95% confidence interval (CI): 12.7-17.4) and 12.9 min (95% CI: 11.5-14.3) for the double-space and NTN techniques, respectively. The median (interquartile range) visual analogue scores for discomfort at insertion were 30 (12.5-51.5) and 32 (12.75-60) and for postoperative backache 0 (0-10) and 0 (0-10.75) in the double-space and NTN groups, respectively. The number of epidural augmentations was similar in both the groups and posture made no difference. There was a tendency to increased success in the second half of the study. CONCLUSION: The double-space technique had a greater success rate than the NTN technique.

Adult↗
PubMed2004

Spacing one's study: evidence for a metacognitive control strategy.

This article investigated individual control of spacing strategies during study. Three predictions were outlined: The spacing hypothesis suggests that people choose to space their study to improve long-term learning via the spacing effect. The massing hypothesis suggests that people choose to mass their study because of illusions of confidence during study. The metacognitive hypothesis suggests that people control their spacing schedules as a function of their metacognitive judgments of specific to-be-learned items. To test these hypotheses, the authors asked participants to study and make judgments of learning for cue-target pairs. Then, participants were given three choices; they could study the pair again immediately (massed), study the pair again after the entire list had been presented (spaced), or choose not to restudy (done). Results supported a metacognitively controlled spacing strategy-people spaced items that were judged to be relatively easy but massed items that were judged as relatively difficult.

Cognition↗
PubMed1985

Spaced dentition. An epidemiologic study.

This epidemiologic study deals with the incidence of spaced dentition in 1279 students between the ages of 12 and 18 years. The sample includes only those with a full complement of permanent teeth (third molars were not considered) and with no apparent etiological conditions that might lead to disruption of dental arch continuity. The sample was evenly divided by age and sex. Frequency of spaced dentition was high, occurring in 51.8% of males and in 45.5% of females. Prevalence was less in higher age groups, and the sexual dimorphism that was significant in the 14 YR-16 YR group was not found in the 16 YR-18 YR group. The mean number of spaces per subject was 6 +/- 4.3 for males and 5 +/- 3.7 for females, again displaying diminishing incidence with age and a concomitant absence of the sexual dimorphism in the highest age group. Spaces were found in both arches in 49.5% of the spaced dentitions, and in only the maxillary arch in 34.3%. Incidence of spacing in the mandibular arch alone was only 16.2%. In most subjects the spaces were distributed equally between the two quadrants of each arch. The most common sites and largest space widths in either dental arch were found between cuspids and the first bicuspids and between cuspids and lateral incisors.

Adolescent↗
PubMed2002

Quantitative evaluation of altered hepatic spaces and membrane transport in fibrotic rat liver.

Four animal models were used to quantitatively evaluate hepatic alterations in this study: (1) a carbon tetrachloride control group (phenobarbital treatment only), (2) a CCl(4)-treated group (phenobarbital with CCl(4) treatment), (3) an alcohol-treated group (liquid diet with alcohol treatment), and (4) a pair-fed alcohol control group (liquid diet only). At the end of induction, single-pass perfused livers were used to conduct multiple indicator dilution (MID) studies. Hepatic spaces (vascular space, extravascular albumin space, extravascular sucrose space, and cellular distribution volume) and water hepatocyte permeability/surface area product were estimated from nonlinear regression of outflow concentration versus time profile data. The hepatic extraction ratio of (3)H-taurocholate was determined by the nonparametric moments method. Livers were then dissected for histopathologic analyses (e.g., fibrosis index, number of fenestrae). In these 4 models, CCl(4)-treated rats were found to have the smallest vascular space, extravascular albumin space, (3)H-taurocholate extraction, and water hepatocyte permeability/surface area product but the largest extravascular sucrose space and cellular distribution volume. In addition, a linear relationship was found to exist between histopathologic analyses (fibrosis index or number of fenestrae) and hepatic spaces. The hepatic extraction ratio of (3)H-taurocholate and water hepatocyte permeability/surface area product also correlated to the severity of fibrosis as defined by the fibrosis index. In conclusion, the multiple indicator dilution data obtained from the in situ perfused rat liver can be directly related to histopathologic analyses.

Albumins↗
PubMed2003

Trapezial space height measurement after trapeziectomy: a comparison of the use of standard and stress radiographs.

PURPOSE: To assess whether the behavior of the trapezial space under stress after excision of the trapezium and insertion of a K-wire to hold the thumb metacarpal base away from the distal pole of the scaphoid for 4 weeks is improved by either palmaris longus interposition or ligament reconstruction (LRTI). METHODS: The trapezial space height and trapezial space ratios were assessed on 50 pairs of standard and stress views obtained 1 year after trapeziectomy. Seventeen of the 50 thumbs had simple trapeziectomy, 15 had trapeziectomy plus LRTI and 18 had trapeziectomy with palmaris longus tendon interposition. The reproducibility of these measurements also was assessed. RESULTS: The 95% limits of agreement for intra- and interobserver differences in the measurement of the trapezial space height were -1 to +1 mm and -2 to +1 mm, respectively. The mean differences between the trapezial heights on the standard and stress radiographs were 1.6 mm (SD, 2.5) for simple trapeziectomy, 1.2 mm (SD, 3.1) for trapeziectomy and LRTI, and 1.2 mm (SD, 2.4) for trapeziectomy with interposition of palmaris longus. The differences between the trapezial space height and trapezial space ratios on the standard and stress radiographs after the 3 different surgeries were not notably different. CONCLUSIONS: Neither the creation of a suspensory ligament nor palmaris longus tendon interposition, as opposed to the isolated placement of a K-wire across the trapezial void for 4 weeks, alters the behavior of the trapezial space under stress at the 1-year follow-up examination. It is thus appropriate to use standard radiographs at the 1-year follow-up examination to assess and compare the trapezial space after these different techniques of trapeziectomy.

Bone Wires↗
PubMed2005

Phase-space overlap measures. II. Design and implementation of staging methods for free-energy calculations.

We consider staged free-energy calculation methods in the context of phase-space overlap relations, and argue that the selection of work-based methods should be guided by consideration of the phase-space overlap of the systems of interest. Stages should always be constructed such that work is performed only into a system that has a phase-space subset relation with the starting system. Thus multiple stages are required if the systems of interest are not such that one forms a phase-space subset with the other. Three two-stage methods are possible, termed umbrella sampling, overlap sampling, and funnel sampling. The last is appropriate for cases in which the subset relation holds, but only in the extreme, meaning that one system's important phase space constitutes a very small portion of the others. Umbrella sampling is most suitable for nonoverlap systems, and overlap sampling is appropriate for systems exhibiting partial phase-space overlap. We review recently introduced metrics that characterize phase-space overlap, showing that the performance of the single- and two-stage methods is consistent with the phase-space picture. We also demonstrate that a recently introduced bias-detection measure is effective in identifying inaccuracy in single- and multistage calculations. The examples used are the chemical-potential calculation for a Lennard-Jones liquid at moderate and at high densities, the same for model water at ambient conditions, and a process of charging a neutral ion in water.

Journal Article↗
PubMed2005

Fisher's theorems for multivariable, time- and space-dependent systems, with applications in population genetics and chemical kinetics.

We study different physical, chemical, or biological processes involving replication, transformation, and disappearance processes, as well as transport processes, and assume that the time and space dependence of the species densities are known. We derive two types of Fisher equations. The first type relates the average value of the time derivative of the relative time-specific rates of growth of the different species to the variance of the relative, time-specific rates of growth. A second type relates the average value of the gradient or the divergence of the relative, space-specific rates of growth to the space correlation matrix of the relative, space-specific rates of growth. These Fisher equations are exact results, which are independent of the detailed kinetics of the process: they are valid whether the evolution equations are linear or nonlinear, local or nonlocal in space and/or time and can be applied for the study of a large class of physical, chemical, and biological systems described in terms of time- and/or space-dependent density fields. We examine the implications of our generalized Fisher relations in population genetics, biochemistry, and chemical kinetics (reaction-diffusion systems). We show that there is a connection between the enhanced (hydrodynamic) transport of mutations induced by population growth and space-specific rate vectors: the velocity of enhanced transport is proportional to the product of the diffusion coefficient of the species and the space rate vector; this relation is similar to a fluctuation-dissipation relation in statistical mechanics.

Analysis of Variance↗