Half Of Zone Research Articles

Calculation of size and location of autologous ipsilateral rotating keratoplasty.

Autologous ipsilateral rotating keratoplasty is a special form of keratoplasty in which a nonprogressive opacification of the centre of the cornea is rotated towards the limbus and the clear peripheral cornea is rotated into the optical axis of the eye. This study was performed to find an equation for calculating the best size and location of the trephine for this special kind of keratoplasty. Geometrical calculations were used to derive the formula. We arrived at the following equation for the best diameter of the trephine: diameter(trephine) = 3/4 diameter(cornea)-1/2e(e = preoperative distance between corneal centre and nearest edge of opacity covering corneal centre). The postoperative diameter of the optical zone is: 2 x diameter(trephine)-diameter(cornea). A postoperative clear optical zone of half the corneal diameter is achieved if the opacity just touches but does not extend beyond the corneal centre. For a postoperative optical zone of at least 30% (40%) of the corneal diameter, the opacity is preoperatively not allowed to extend beyond the corneal centre for more than 20% (10%) of the corneal diameter. This equation can be used for calculating the optimum size and location of the trephine for autologous ipsilateral rotational keratoplasty. For that purpose it is advisable to take photographs preoperatively.

Bouyant and thermocapillary flow in liquid encapsulated floating zone

Buoyant and thermocapillary flow in axisymmetric liquid bridges of GaAs melt and its encapsulant B2O3 are studied numerically. The liquid bridges are heated either at the top or at the bottom (half zone). The results show that, when the liquid bridges are heated at the bottom, buoyant flow enforces and dominates over Marangoni flow. On the contrary, when the bridges are heated at the top, flow in the melt is reduced by the opposing buoyancy effect. The motion in the encapsulant B2O3 is essentially unaffected due to its high viscosity and remains interfacial tension driven flow. In the presence of gravity, the deformation of the melt-encapsulant interface is caused mainly by hydrostatic pressure at small temperature differences. However, with increased temperature difference, the capillary pressure effect can become so strong as to totally reverse the deformation of the interface when the bridges are heated at the top. The presence of encapsulant B2O3 significantly decreases the thermocapillary convection in GaAs melt and increases the capillary stability of the liquid bridges.

Diode Laser Photocoagulation for Prethreshold, Posterior Retinopathy of Prematurity

Nine infants with posterior retinopathy of prematurity were treated by using the diode laser through an indirect ophthalmoscopic delivery system. Treatment was commenced as soon as plus disease (defined as tortuosity and dilation of posterior vessels) developed. We defined posterior retinopathy of prematurity as retinopathy of prematurity located in zone 1 (the limits of zone 1 are defined as twice the disk-fovea distance in all directions from the optic disk, that is, an arc of 60 degrees centered on the optic disk) or the posterior one half of zone 2 (zone 2 extends from the edge of zone 1 peripherally to a point tangential to the nasal ora serrata and around to an area near the temporal anatomic equator). Disease regressed in all eyes. These results are encouraging and represent an improvement over the results obtained by allowing these eyes to reach threshold (threshold disease is defined as 5 or more contiguous or 8 total clock hours of neovascularization in zone 1 or 2 in the presence of plus disease) before intervention.

Seismic gaps in Hawaii

Abstract We propose that two seismic gaps exist in southern Hawaii. From their dimensions and tectonic setting, we estimate that the south Kona gap may be capable of a mainshock in the magnitude range of 714 to 712, while the east Kona gap will probably not produce earthquakes larger than M=612. During historic time (1832 to the present), no mainshocks have occurred in these gaps. Since there is no evidence that fault creep relieves stress in these areas, we expect earthquakes to fill these gaps. The boundaries of the south Kona gap are defined by the approximate rupture extent of the earthquakes of 2 April 1868 (M = 7.9) and 21 August 1951 (M = 6.9), those of the east Kona gap by the latter mainshock and the extent of the seismogenic zone. The seismotectonic model on which we base our gap hypothesis defines a major seismic zone in the southern half of the island of Hawaii. We propose that most major and large earthquakes within this zone are of a decollement type, in which the upper 10 km of the crust is pushed seaward along a near-horizontal plane of weakness, provided by the oceanic sediments buried beneath the volcanic edifice. The direction of slip is away from the volcano summits and perpendicularly away from the volcano rifts. Several recurrence intervals are known for the Kaoiki area, where M = 6 ± 0.6 mainshocks occur every 10.4 ± 1.5 years. For the Kalapana area, one recurrence interval of 108 years is known for earthquakes with 7 < M < 8. In most of the major seismic zone in Hawaii, the recurrence times are not known, and no information on strain accumulation rate is available. It is therefore not possible to estimate when the portion of the 1868 rupture that has not re-ruptured yet (southern Kau) will produce another large mainshock. The potential for a large earthquake in this area is estimated to be intermediate. The potential in the Kalapana, the central Kona, and northern Kona areas are estimated to be low for the next several decades.

The inheritance of patterned white flowers in zonal pelargoniums

White flowered cultivars have petals which are either pure white, or patterned white with coloured markings localized within clearly defined zones on the upper surface of the petals. Five patterns are identified. The bar pattern has pigment localized within a small zone on both sides near the base of each of the lower triplet of petals. The centre pattern has a V-shaped coloured zone in the basal half of all petals filling in the centre of the flower. The picotee pattern colours the edges of all petals. The ring pattern is a coloured zone running across the basal half of all petals. The vein pattern consists of two prominent coloured veins running from the base of the upper pair of petals. The expression of these patterns is controlled by the dominant alleles of four genes: the bar, picotee and vein patterns by the genes Baiba, Celce or PH pi, and Ve/ve respectively, and the centre and ring patterns by the interaction of the products of two genes Ce with Ve and Ba with Ve respectively. The homozygous rece...

AUTORADIOGRAPHIC STUDY OF DIGESTIVE TRACT CARCINOGENESIS INDUCED BY N-METHYL-N'-NITRO-N-NITROSOGUANIDINE (MNNG) IN RAT

Various mucosal changes of the digestive tract induced by 75 mg/l MNNG plus 3 g/l Tween-60 dissolved into tap water in Wistar female rats were autoradiographically and histologically studied, and the following results were obtained.1) The incidence of the tumor in rats administered orally for more than 10 months was 47% in the stomach and 73% in the small intestine.2) The number of labeled cells (NLC) in 6-week-aged normal rats was 100 in the small intestine, 26.6 in the pyloric gland, 20.6 in the oxyntic gland and 12.6 in the colon. Tumors were frequently found in the small intestine and pyloric gland showing higher NLC by administration of MNNG.3) Increases of NLC and positive NLC-a were found in the mucosa of the pyloric gland and small intestine 6 months after administration of MNNG, and epithelial tumor, descending adenomatous hyperplasia and sarcoma developed 10 months after administration.4) Autoradiographically, cells of the proliferative zone in the lower half of mucosae of normal pyloric gland and small intestine were labeled in a regular manner, while labeled cells in the regenerative mucosa induced by administration of MNNG were found near the luminal surface.

A half-zone study of Marangoni convection in floating-zone crystal growth under microgravity

Floating-zone crystal growth under microgravity, though free from natural convection, can still be susceptible to Marangoni convection. The use of a ring heater in contact with most of the surface of the melt zone, has recently been considered as one way of reducing Marangoni convection in the melt zone. In order to study Marangoni convection in the melt zone in this modified floating-zone crystal growth process, a half zone system was adopted. Computer simulation and direct observation of Marangoni convection in the half-zone system were carried out for two different cases. In the first case, the surface of the melt zone was completely free, while in the second it was mostly in contact with a quartz ring. The results of computer simulation and direct observation both indicated that in the second case Marangoni convection was significantly reduced near the melt/solid interface as well as in the bilk melt.

Distribution, morphology and habenular projections of adenosine deaminase-containing neurons in the septal area of rat

Adenosine deaminase (ADA) was localized within several types of neurons within the septum and in septal efferent projections to the habenula by immunohistochemical, biochemical, retrograde tracing and lesion methods. Numerous ADA-immunoreactive (ADA-IR) neurons were observed in the septofimbrial nucleus, the triangular septal nucleus and the bed nucleus of the anterior commissure, while considerably fewer numbers were seen in the lateral septal area. Based on their size, shape and dendritic features, 4 morphologically distinct types of ADA-IR neurons were recognized in these septal structures. In addition, fine, non-varicose, ADA-IR fibers appeared to emanate from the postcommissural cell groups and these coalesced within the stria medullaris, continued caudally within this fiber bundle, and gave rise to a dense field of very fine immunoreactive elements within a restricted zone of the dorsal half of the medial habenula. Comparisons of the habenular localization of ADA-IR and enkephalin-IR elements showed that fibers labelled for either ADA or enkephalin occupied distinct, non-overlapping regions within the dorsal half of the medial habenula. After injections of Fluoro-gold (FG) into the medial habenula, the majority of ADA-IR neurons in the septofimbrial nucleus, triangular septal nucleus, and the bed nucleus of the anterior commissure were retrogradely labelled with this fluorescent tracer, whereas no ADA-positive FG-labelled neurons were observed in the lateral septal region. Unilateral transections of the stria medullaris caused substantial depletions of ADA-immunoreactivity and reduced enzymatically determined ADA activity by up to 80% in the medial habenula on the lesioned compared with the contralateral control side. These results demonstrate that ADA-IR neurons in the septum are heterogeneously distributed and that populations of positive neurons within the postcommissural septal nuclei give rise to dense, focal projections to the medial habenula. These projections appear to be restricted to a portion of the medial habenula known to contain substance P-IR neurons and are subregionally segregated from enkephalin-positive septohabenular projections ending within this same portion. In addition to pointing out a unique capacity for adenosine catabolism within some septal neurons, possibly related to purinergic neuromodulation, the results indicate the utility of ADA-immunohistochemistry for the delineation of anatomical relationships between the septum and the medial habenula.

The isolation of functionally heterogeneous hepatocytes of the proximal and distal half of the liver acinus in the rat.

The objective of this study was to isolate hepatocytes of the proximal half (Zones 1 and 2) or distal half (Zones 2 and 3) of the liver acinus. The zonal origin of the isolated hepatocytes was recognized by: the presence in hepatocytes of a fluorescent marker, acridine orange, selectively delivered to either the proximal or the distal half of the acinus by in situ perfusion prior to cell isolation and the measurement of the induction of cytochrome P-450 by phenobarbital, an induction known to occur predominantly in the distal half of the acinus. Following the selective labeling of the acinus with acridine orange, livers were perfused with collagenase in either the portal to hepatic vein direction (anterograde) or in the retrograde direction. Hepatocytes isolated by either an anterograde or a retrograde perfusion were separated by centrifugation in a Percoll density gradient. This procedure isolated populations of proximal or distal hepatocytes, respectively, which were intact and 90% fluorescent. In an effort of assessing the heterogeneity of the separated proximal and distal hepatocytes, each population was further fractionated by centrifugal elutriation. This resulted in the arbitrary separation of proximal or distal hepatocytes into five fractions. Total cytochrome P-450 was determined spectrophotometrically in each of the fractions isolated from controls and after 3 days of the in vivo administration of phenobarbital. On the basis of the pattern of fluorescence in isolated hepatocytes and on the cytochrome P-450 inductive response to phenobarbital administration, it is proposed that: the anterograde or retrograde perfusion of the liver with collagenase separated hepatocytes predominantly of the proximal or distal half of the liver acinus, respectively and that hepatocytes of the distal half of the liver acinus responded to phenobarbital administration with the highest level of cytochrome P-450 induction, indicating that the isolated hepatocytes conserved the functional heterogeneity observed in vivo.

Confinement of thermocapillary floating zone flow by uniform rotation

The microgravity environment of an orbiting vehicle permits crystal growth experiments with greatly reduced buoyant convection in the liquid melt. Crystals grown in ground-based laboratories do not achieve their potential properties because of dopant variations caused by flow in the melt. The floating zone crystal growing system is widely used to produce crystals of silicon and other materials. However, in this system the temperature gradient on the free sidewall surface of the melt is the source of a thermocapillary flow which does not disappear in a low gravity environment. Smith and Greenspan examined theoretically the idea of using a uniform rotation of the floating zone system to confine the thermocapillary flow to the melt sidewall leaving the interior of the melt passive. These workers considered a half zone, a cylinder of fluid with a constant axial temperature gradient imposed on the cylindrical sidewall. They examined the linearized, axisymmetric flow in the absence of crystal growth. They found that rotation does confine the linear thermocapillary flow. In this paper the simplified model of Smith and Greenspan is extended to a full zone with a more realistic temperature distribution imposed on the sidewall and both linear and nonlinear thermocapillary flows are studied theoretically. Analytical and numerical methods are used for the linear flows and numerical methods for the nonlinear flows. We found that the linear flows in the full zone have more complicated and thicker boundary layer structures than in the half zone, and that these flows are also confined by the rotation. For the model considered and for realistic values for silicon, however, the thermocapillary flow is not linear. We examined the nonlinear flows by first computing a weakly nonlinear flow and then computing the fully nonlinear flow. The weakly nonlinear flow is steady, has less boundary layer character, and penetrates more deeply into the interior than the linear flow but still shows some rotational confinement. The fully nonlinear flow is strong and unsteady (a weak oscillation is present) and it penetrates the interior. Some non-rotating flow results are also presented. Since silicon has a large value of thermal conductivity, we would expect the temperature fields to be determined by conduction alone. This is true for the linear and weakly nonlinear results, but for the stronger nonlinear flow the results show that temperature advection is also important. Thus, this work reveals that for the nonlinear flow, a radiative sidewall boundary condition would be an improvement over the specified temperature boundary condition used in this paper and previously by others. Such a boundary condition would weaken the sidewall axial temperature gradient and hence the thermocapillary flow, allowing the confining effect of rotation to play a stronger role. Hence, uniform rotation may still be a means of confining the flow, and the results obtained define the procedure to be used to examine this hypothesis.

3H]thymidine autoradiographic and alkaline phosphatase histochemical studies of intestinal metaplasia of the human stomach.

The relationship between cell proliferation and enzyme activity in intestinal metaplasia of the human stomach was studied using a combined method of [3H]thymidine autoradiography and alkaline phosphatase histochemistry on the same section. Three types of intestinal metaplasia were observed depending on variations in both enzymatic activity and isotope labelling. One type shows alkaline phosphatase-positive cells along the entire length of the glands with [3H]thymidine-labelled cells localized only at the bottom of the glands, resembling the duodenum. In another type of intestinal metaplasia, alkaline phosphatase-positive cells are present on the surface and/or upper half of the glands with mitotically active cells occupying the lower part of the glands. The third variety of intestinal metaplasia is characterized by the absence of alkaline-phosphatase activity and [3H]thymidine-labelled cells present in an extended zone in the lower half of the glands. Differences in labelling patterns of [3H]thymidine and the activity of marker enzyme in various types of intestinal metaplasia seem to reflect variations in cell differentiation during intestinalization of gastric mucosa.

日本海の後期第四紀けいそうと古海況

To delineate the paleoceanography of the Sea of Japan since the last glacial maximum, I first tried to formulate the relationship between the present-day distribution and physico-chemical properties of surface water masses and the diatom flora in the modern sediments collected at 78 stations which are widely distributed in the sea. Then the results from this examination were applied for the upper portion of eight piston cores with the assistance of key tephra and its 14C age for a time scale.The floral analysis of the diatoms in modern sediments is performed by principal components analysis employing the Q-mode variance-covariance matrix. On floral analysis, two species associations are defined by the second principal component; species association in the warm-current region (Pseudoeunotia doliolus, Melosira sulcata and Thalassiosira oestrupii) and one in the cold-current region (Denticulopsis seminae, Thalassiosira sp. 1 and Thalassiosira nordenskioeldii), From relative frequency of these species at a random count of about 200 diatom specimens for each sample, R value was obtained to facilitate the application of the results from the diatoms in modern sediment samples to core samples. The value is defined as:R=(P. doliolus+M. sulcata+T. oestrupii)/(P. doliolus+M. sulcata+T. oestrupii+D. seminae+T. sp. 1+T. nordenskioeldii)The value are generally constant below a certain surface water masses classified by their physico-chemical properties. From interpretation of the third principal component, the relative frequencies of Pseudoeunotia doliolus and Melosira sulcata provide a useful clue to estimate the degree of the influence of low saline water of the upper surface water in the southern part of the sea; Pseudoeunotia doliolus is dominant in samples from the high saline area, and Melosira sulcata in those from the low saline area.The paleoceanography of the Sea of Japan since the last glacial maximum are deduced on the basis of these criteria as follows: 1) The supply of the warm water which have a similar oceanographic structure to the present-day Tsushima Warm Current, began about 7, 000-8, 000y.B.P. 2) The frontal zone in the eastern half of the Sea of Japan was to the south of its present position, and its southern boundary reached at least as far as the eastern offing of the Oki Islands during a period, from about 15, 000 to 9, 000y.B.P. in conservative estimation, following decrease of the sea water supply through the Tsushima Straits. 3) The zone at that time was probably formed between the low saline water brought from the East China Sea and the cold water which occupied the northern part of the sea. 4) The low saline water probably occupied the surface layer of the southern part of the sea at the last glacial maximum.

Some evidence for the existence and magnitude of a critical marangoni number for the onset of oscillatory flow in crystal growth melts

Experiments on floating half zones of NaNO 3 heated from above show the onset of oscillatory Marangoni convection at a critical Marangoni number Ma( T) c ∼ 10 4. The dependence of Ma( T) c on zone length is investigated and discussed. Literature on the onset of temperature oscillations is reviewed. It gives Ma( T) c of the same order of magnitude for other melts. Effects of oscillatory Marangoni convection in crystal growth from melt are discussed. A description of the state of oscillatory Marangoni convection in this geometry is given.

Projections of the dorsal column nuclei and the spinal cord on the inferior olive in the cat

This study demonstrated partially overlapping fiber termination areas in the inferior olive originating from the dorsal column nuclei and the spinal cord. Based on the distribution of the dorsal accessory olive can be divided into a rostral and a caudal part. In the caudal part terminations are found of fibers originating in the contralateral gracile nucleus and in the lumbar and cervical spinal cord. Terminations in the rostro-medial part of the dorsal accessory olive arise from the contralateral internal cuneate nucleus and from the opposite intermediate grey at C.1. Fibers from more caudal regions of the internal cuneate nucleus terminate in the dorsal accessory olive caudal to those originating from more rostral regions of this nucleus. The gracile nucleus and the lumbar spinal cord project to the rostro-lateral portion of the dorsal accessory olive. The terminations in the medial accessory olive from the lumbar spino-olivary fibers are found in a laterally located zone in the caudal half of the medial accessory olive, while terminations of the contralateral internal cuneate nucleus are found at a more rostral level in the medial part of the medial accessory olive. Connections between the inferior olive and the caudal part of the spinal trigeminal nucleus, the lateral cervical nucleus and the cervical dorsal horn could not be demonstrated.