Pengaruh Pemodelan Zona Terkekang Terhadap Prediksi Hubungan Momen-Kurvatur Kolom Persegi Beton Mutu Tinggi

. This paper studies one aspect of confinement modeling of high strength concrete square columns subjected to axially eccentric compression. Confined zone models were studied to evaluate their effect on the analytical prediction of strength and ductility of high strength concrete square columns. Several models of confined zones found in literatures were discussed to observe their characteristics and sensitivity. Based on the findings, a computer program MOKUR2D was developed. In the program, confined zone in reinforced concrete columns can be modeled with three different approaches, i.e. conventional models (using a coefficient of effective confinement), models with unconfined arching zone, or models with three zones of confinement. A comparative study using the program was later carried out on 4 high-strength concrete square columns tested by Sheikh and Bayrak [1998]. The cross-section size of all columns was 305 x 305 mm. All columns were reinforced with 8 bars of 19.5 mm diameter, uniformly distributed around the core perimeter. Yield strength of the rebars was 454 MPa. Two types of ties configuration ties were used with volumetric ratio varying from 1.68 percent to 5.12 percent. The spacing of the ties was from 90 mm to 108 mm. From the study, it was found that the conventional model is able to produce a fairly good estimate of test results. The best estimate of test results is given by the model with three zones of confinement in which the arching zoneis assigned with 50% of full confinement

Ovarian reserve and anti-Mullerian hormone (AMH) in mothers of dizygotic twins

This study aimed to explore if natural dizygotic (DZ) twinning is associated with earlier menopause and lower anti-Mullerian hormone (AMH) values. We investigated if advanced biological reproductive aging, which can be responsible for the multiple follicle growth in familial twinning, is similar to mechanisms that occur in normal ovarian aging, reflected by earlier menopause in mothers of DZ twins and lower levels of AMH. A total of 16 mothers of DZ twins enrolled with the Netherlands Twin Register (average age at first assessment: 35.9 +/- 3.0 years) and 14 control mothers (35.1 +/- 3 years) took part in a prospective study. Fifteen years after entry into the study, which included follicle-stimulating hormone (FSH) assessment, AMH was measured in stored serum samples and menopause status was evaluated. Average AMH levels were not significantly different between DZ twin mothers and controls (2.1 +/- 2.4 mu g/L vs. 1.9 +/- 1.9 mu g/L). Among the 16 mothers of twins, 7 had an elevated (FSH) value over 10 U/L at first assessment. Their AMH levels were lower than the nine twin mothers with normal FSH values: 0.6 +/- 0.4 versus 3.4 +/- 2.6 mu g/L (p = .01). Of the mothers of twins, eight mothers had entered menopause at the second assessment compared with only one control mother (p = .07). Thus, slightly more DZ mothers were in menopause than the control mothers, although this difference was not significant. The subgroup of DZ twin mothers who had an increased FSH concentration 15 years ago had a limited ovarian reserve as reflected by lower AMH levels. These data indicate that advanced ovarian aging can be a feature in familial DZ twinning, particularly with elevated early follicular phase FSH

Does mental health service integration affect compulsory admissions?

Background: Over recent years, the number of compulsory admissions in many countries has increased, probably as a result of the shift from inpatient to outpatient mental health care. This might be mitigated by formal or collaborative relationships between services. <br><br> Methods: In a retrospective record linkage study, we compared two neighboring districts, varying in level of service integration. Two periods were combined: 1991–1993 and 2001–2003. We included patients aged 18–60, who had a first emergency compulsory admission (n=830). Their psychiatric history was assessed, and service-use after admission was monitored over a 12-month follow-up. <br><br> Results: Over a 10-year period, compulsory admission rates increased by 47%. Difference in relative increase between the integrated and non-integrated services was 14%. Patient characteristics showed different profiles in the two districts. Length of stay was >10 days shorter in the integrated district, where the proportion of involuntary readmissions decreased more, and where aftercare was swift and provided to about 10% more patients than in the non-integrated district. <br><br> Conclusions: Services outcomes showed better results where mental healthcare was more integrated. However, limited effects were found and other factors than integration of services may be more important in preventing compulsory admissions

The role of lateral drag in the dynamics of Ice Stream B, Antarctica

The partitioning of resistive force between the bed and sides of Ice Stream B, Antarctica , is obtained for three large areas that have bee n measured using repeat aerial photogrammetry. Problems associated with data errors and local variations in ice strength and velocity are reduced by considering the a really ave raged budget of forces for each photo block. Results indicate that the bed under Ice Stream B must be very weak and unable to provide much res instance. Mechanical l control on this ice stream emanates almost entirely from the lateral margins

Flow laws for glacier ice: comparison of numerical predictions and field measurements

This is the published version, also available here: http://dx.doi.org/10.3189/002214390793701372.Ice flow along the 20 km long strain network up-stream of the Dye 3 bore hole in Greenland is studied in detail. By solving the force—balance equations and using selected flow laws, stresses and strain-rates are calculated throughout the section of the ice sheet. The validity of the results is evaluated by comparison with the velocity profile derived from bore-hole-tilting measurements, and with observed surface strain-rates. A number of constitutive relations are tried and most predict a velocity profile at the bore-hole site that is in good agreement with that observed, if appropriate enhancement factors are used. However, there are major discrepancies between modeled and measured surface strain-rates. Use of Nye's generalization of Glen's flow law, or an anisotropic constitutive relation, requires unrealistically large along-flow variations in the enhancement factor. Inclusion of normal stress effects can lead to much better agreement, but it is possible that other processes, such as dynamic recrystallization or primary creep, should be included in the constitutive relation of polar ice

Force Budget: II. Application to Two-Dimensional Flow Along Byrd Station Strain Network, Antarctica

This is the published version, also available here: http://dx.doi.org/10.3189/002214389793701455.Resistive stresses and velocities at depth are calculated along the Byrd Station Strain Network, Antarctica, using field data. There are found to be large longitudinal variations in basal drag and this result is little affected by errors in the input data or by uncertainties in the constitutive relation for ice. Basal drag varies by a factor of about 2 along the strain network, and is usually equal to the driving stress to within 10–20%. Sites of high drag are not always correlated with basal topographic highs, indicating that some process such as basal water drainage is involved in controlling the friction at the bed. Basal sliding velocities are very sensitive to errors in measured surface velocities and the rate factor in Glen's flow law. As a result, calculated sliding velocities are much less reliable than deep stresses, and need to be interpreted with caution

Reply to Lliboutry's letter 'Why calculated basal drags of ice streams can be fallacious'

This is the publisher's version, copyright by the International Glaciological Society.No abstract is available for this item

Determination of a flow center on an ice cap

This is the published version.A method for identifying the center of ice flow is developed and applied using results from surveys of a strain grid near the summit of Dunde Ice Cap (central China). Strain rates are used to compute stresses. These are used with a consideration of the balance of forces to compute basal friction. The flow center at the bed occurs where this friction changes sign. For Dunde Ice Cap, the basal flow center nearly underlies the summit

New and improved determinations of velocity of ice streams B and C, West Antarctica

This is the publisher's version, copyright by the International Glaciological Society.Measurements of velocity have been made on and next to Ice Streams B and C, West Antarctica. The results are more precise than previous work and constitute a 93% increase in the number of values. These velocities are used to describe the confluence of flow into the ice streams and the development of fast icestream flow. The onset of fast-streaming flow occurs in many separate tributaries that coalesce down-glacier into the major ice streams. For those inter-stream ridges that have been studied, the flow is consistent with steady state. Along Ice Stream B, gradients in longitudinal stress offer little resistance to the ice flow. The transition from basal-drag control to ice-shelf flow is achieved through reduced drag at the glacier base and increased resistance associated with lateral drag. Velocities in the trunk of Ice Stream C are nearly zero but those at the up-glacial head are similar to those at the head of Ice Stream B