ORBITOLINA DAVIESI HOFKER, 1966: A FORGOTTEN ORBITOLINIDAE FROM THE THANETIAN OF PAKISTAN AND ITS TAXONOMIC STATUS

Orbitolina daviesi Hofker, 1966 (family Orbitolinidae) was validly described and thoroughly illustrated from Thanetian limestones of Pakistan. Although its attribution to the genus Orbitolina d’Orbigny and any phylogenetic relationships with the Cretaceous taxa have been refuted shortly afterwards, the species has not been taxonomically revised since then. Karsella hottingeri Sirel, 1999 was established as new genus and new species from the Thanetian of Turkey, without taking into account J. Hofker’s publication. The original description and genus diagnosis of Karsella has meanwhile been emended to include the occurrence of a radial zone with septula that follow a zig-zag pattern and associated linear arrangement of the foramina, as well as a complex embryo. Orbitolina daviesi clearly displays these features and is here considered a species of the genus Karsella Sirel. Karsella hottingeri is regarded as a subjective junior synonym of O. daviesi Hofker and therefore, the only species of the genus is given as a new combination: Karsella daviesi (Hofker). From a suprageneric viewpoint, the two Paleogene genera Karsella Sirel and Cushmania Silvestri display a complex embryo and might belong to a new subfamily of the Orbitolinidae, phylogenetically different and unrelated to the lower-mid Cretaceous Orbitolininae.

The Effect of Heat Induction on Shear Strength of Soft Soil in Radial Zone

The main problem in infrastructure development at the soft clay was its bearing capacity therefore it needs to be improved. In this research, the improvement method was carried out by modeling in small scale of preloading and heat induction combination. Location of soft clay sampling was in Takalar, Indonesia. The purpose of this study was to investigate the change of the shear strength of soft soil corresponding with heat induction at the radial zone. The shear strength was obtained by vane shear test and compressive strength from unconfined compressive test (UCT). The heat applied ranging from 100o C, 200o C, 300o C, and 400o C with static preloading load 0.20 kg/cm2. The strengths of the soil in radial zones have been tested at R0, R1, and R2. At lowest temperature 100° at R0 the compressive strength was 0.203 kg/cm2, at highest temperature 400° at R0 the compressive strength 0.467 kg/cm2, there was a significant increasing of compressive strength value with the change of temperature. At the highest temperature 4000 the shear strength from vane shear tests resulting at R0 0.240 kg/cm2, R1 of 0.128 kg/cm2, R2 of 0.077 kg/cm2. At the lowest temperature of 100o C shows R0 at 0.116 kg/cm2, R1 at 0.070 kg/cm2, R3 of 0.046 kg/cm2. The results show a tendency of declining strength value as the soil farther away from center of heat induction. The experimental result from this model produces strength that can be used as a parameter of the foundation model on soft soil.

Imaging structural and mechanical properties of articular cartilage using optical polarization tractography

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Osteoarthritis (OA) is an extremely common joint disease, which affects more than one-third of all adults in the USA. Although the entire joint compartments are involved, OA is considered as a cartilage disease. Articular cartilage is a thin tissue covering the end of bones in the diarthrodial joints and plays a crucial role in providing a frictionless articulation. In spite of the harsh mechanical environment, cartilage has an amazingly long life due to its unique structure and composition. Cartilage is composed of ~80% water and ~20% solid matrix that mainly consists of collagen fibers and proteoglycans. Collagen degeneration is often an early symptom in OA. Since the fiber structure governs normal functionality in cartilage, the disease progression leads to impaired mechanical functions. Hence, an effective imaging technology that can visualize the collagen organization and its effects on cartilage mechanical properties will help to understand the sophisticated structure-function relationship in cartilage. Polarized light macroscopy (PLM) has been broadly utilized for collagen assessment; however, it requires thin, sectioned samples and thus remains a destructive technology. We introduced a nondestructive alternative to PLM for cartilage imaging using optical polarization tractography (OPT). OPT improved visualization and characterization of the zonal structure in cartilage by calculating the depth-resolved local birefringence and fiber orientation. We demonstrated that parametric imaging can be implemented using multiple complementary tissue contrasts obtained in OPT including surface roughness, birefringence, and fiber dispersion. We showed that parametric OPT imaging provided a morphometric evaluation of collagen damage in human OA cartilage samples. Because OPT can accurately quantify tissue optical birefringence, it can reveal the higher level of complexity in collagen architecture of cartilage. Our multi-incident OPT based biaxial birefringence measurement provided strong evidence of the existence of a leaf-like structure in cartilage. Furthermore, we expanded the capability of OPT technology by developing a method that can simultaneously image the fiber organization and mechanical responses in cartilage. This new method enabled a precise characterization of the zonal structural and mechanical responses to unconfined compressive and directional shear loading. We discovered that the upper part of the radial zone plays a critical role in absorbing compression-induced deformation in cartilage. Young's modulus in cartilage was strongly correlated with the optical birefringence. In the shear test, we found a remarkably higher shear modulus in the radial zone when the sample was sheared along the fibers. In summary, this dissertation research developed new OPT based imaging methods that can fully characterize the collagen organization and its responses during mechanical loading. This new technology has a great potential for nondestructive structural and functional imaging in articular cartilage.

Characterization of the collagen microstructural organization of human cervical tissue

The cervix shortens and softens as its collagen microstructure remodels in preparation for birth. Altered cervical tissue collagen microstructure can contribute to a mechanically weak cervix and premature cervical dilation and delivery. To investigate the local microstructural changes associated with anatomic location and pregnancy, we used second-harmonic generation microscopy to quantify the orientation and spatial distribution of collagen throughout cervical tissue from 4 pregnant and 14 non-pregnant women. Across patients, the alignment and concentration of collagen within the cervix was more variable near the internal os and less variable near the external os. Across anatomic locations, the spatial distribution of collagen within a radial zone adjacent to the inner canal of the cervix was more homogeneous than that of a region comprising the middle and outer radial zones. Two regions with different collagen distribution characteristics were found. The anterior and posterior sections in the outer radial zone were characterized by greater spatial heterogeneity of collagen than that of the rest of the sections. Our findings suggest that the microstructural alignment and distribution of collagen varies with anatomic location within the human cervix. These observed differences in collagen microstructural alignment may reflect local anatomic differences in cervical mechanical loading and function. Our study deepens the understanding of specific microstructural cervical changes in pregnancy and informs investigations of potential mechanisms for normal and premature cervical remodeling.

Preservation of Articular Cartilage for Electron Microscopy

Water makes up 60-80% of the wet weight of articular cartilage. The remaining parts of this tissue are made up of a variety of cells, generally referred to as chondrocytes, and an extracellular matrix of, collagen fibrils (types II, IX and XI), proteoglycans. The collagens and proteoglycans, with associated water, are assembled into a structure that is capable of withstanding considerable loading.The micro-structure of adult rabbit articular cartilage has been described, based upon ultrastructural studies. The tissue is arranged into zones, mainly based on the general orientation of collagen fibrils (See Figure 1). The collagen framework in the radial zone forms a continuous area of radially oriented and tightly bound collagen fibrils, in which are embedded at regular interval, tubular inclusions of proteoglycans (Figure 2). in rabbit tibial plateau tissue these inclusions have diameter of 1-3 fim and can be continuous from the calcified to the tangential zone.

Induced Seismicity of The Tarbela Reservoir, Pakistan

Earthquakes with local magnitudes from 0.0 to 4.9 recorded by the Tarbela seismic network, in Pakistan, between 1973 and 1982 have been used to study the reservoir-induced seismicity. A comparison between the pre-impounding and the post-impounding seismicity shows a dramatic decrease in the latter. The sharp decrease in seismicity is not related to the reservoir filling since it started two months before the first impounding and affected a very large area extending more than 100 km away from the reservoir. Statistical analyses of the distributions of earthquakes that occurred within the 20-km radial zone centered on the reservoir indicate that earthquakes in the magnitude range 0.0–1.9 are not randomly distributed in time, while larger events (2≤ML <5 ) have a random temporal distribution. Further analysis of the occurrence of larger magnitude earthquakes indicates that there is no simple relationship between their occurrence and the reservoir loading. On the other hand the cross-correlation of the frequency of non-random small-sized events in a 20-km radial zone with the monthly reservoir water level shows that there is a 160-day lag between the two time-series. This time lag, equivalent to a 180° phase shift between the water level curve and the event curve, indicates that the frequency of microearthquakes is reduced when the reservoir level is at high stand and vice-versa. An elastic model consisting of a two-dimensional rectangular load predicts that the effect of reservoir loading alone is to suppress the pre-existing seismicity directly beneath the Tarbela reservoir, while the effect of unloading the reservoir is to lead to a partial recovery of seismicity. The positive correlation between the frequency of earthquakes and the low reservoir water level could be explained mostly by the elastic effects of reservoir unloading. A gradual increase in the seismicity in regions as far as 100 km from the reservoir started in 1979 (five years after the first reservoir filling) and appears not to be a consequence of the slow diffusion of water to hypocentral depths; rather it reflects the long-term behavior of seismicity in the Pakistan Himalayas.