Ultrasonography reveals massive ascites (a) and a 16 cm 12 cm multiseptated ovarian tumor with a solid component (b). (c) Computed tomography of the abdomen and pelvis displays an ovarian mass about 20 cm 18 cm
Abdominal MRI revealed the same findings of the huge left ovarian mass with thick enhanced septa, containing fat and few foci of calcification. The cystic part of the mass showed dark T1, bright T2 signal intensity, the fatty component was bright on the non-fat saturated T1 and T2 weighted images and suppressed on T1 fat-saturated pre-contrast images. The right ovary was normal. Along with the massive ascites scalloping the liver, there were multiple- peritoneal deposits, the largest measured 1.8 cm (Figure 2).
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the current age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.
Nuclear fusion powers a star for most of its existence. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red-giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their existence, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.
When a star exhausts the hydrogen in its core, it leaves the main sequence and begins to fuse hydrogen in a shell outside the core. The core increases in mass as the shell produces more helium. Depending on the mass of the helium core, this continues for several million to one or two billion years, with the star expanding and cooling at a similar or slightly lower luminosity to its main sequence state. Eventually either the core becomes degenerate, in stars around the mass of the sun, or the outer layers cool sufficiently to become opaque, in more massive stars. Either of these changes cause the hydrogen shell to increase in temperature and the luminosity of the star to increase, at which point the star expands onto the red-giant branch.
Another well known class of asymptotic-giant-branch stars is the Mira variables, which pulsate with well-defined periods of tens to hundreds of days and large amplitudes up to about 10 magnitudes (in the visual, total luminosity changes by a much smaller amount). In more-massive stars the stars become more luminous and the pulsation period is longer, leading to enhanced mass loss, and the stars become heavily obscured at visual wavelengths. These stars can be observed as OH/IR stars, pulsating in the infrared and showing OH maser activity. These stars are clearly oxygen rich, in contrast to the carbon stars, but both must be produced by dredge ups.
These mid-range stars ultimately reach the tip of the asymptotic-giant-branch and run out of fuel for shell burning. They are not sufficiently massive to start full-scale carbon fusion, so they contract again, going through a period of post-asymptotic-giant-branch superwind to produce a planetary nebula with an extremely hot central star. The central star then cools to a white dwarf. The expelled gas is relatively rich in heavy elements created within the star and may be particularly oxygen or carbon enriched, depending on the type of the star. The gas builds up in an expanding shell called a circumstellar envelope and cools as it moves away from the star, allowing dust particles and molecules to form. With the high infrared energy input from the central star, ideal conditions are formed in these circumstellar envelopes for maser excitation.
In massive stars, the core is already large enough at the onset of the hydrogen burning shell that helium ignition will occur before electron degeneracy pressure has a chance to become prevalent. Thus, when these stars expand and cool, they do not brighten as dramatically as lower-mass stars; however, they were more luminous on the main sequence and they evolve to highly luminous supergiants. Their cores become massive enough that they cannot support themselves by electron degeneracy and will eventually collapse to produce a neutron star or black hole.
The most massive stars that exist today may be completely destroyed by a supernova with an energy greatly exceeding its gravitational binding energy. This rare event, caused by pair-instability, leaves behind no black hole remnant. In the past history of the universe, some stars were even larger than the largest that exists today, and they would immediately collapse into a black hole at the end of their lives, due to photodisintegration.
Major opportunities for production optimization in mature oil provinces are typically scarce, more so, if throughout the long lives of the fields nearly all conventional optimization strategies have already been attempted and implemented. The re-development project presented in this and its companion paper1 (SPE 104041) looked at the technical and business opportunities for two main re-development components. The first component aims to beat the natural production decline curve via the implementation of a massive infill drilling program; the second component aims to maintain production levels through the integration of various Improved Oil Recovery (IOR) methodologies.
A multi-disciplinary team studied and recommended the implementation of a massive infill drilling program in a portion of Block 10, operated by Petrobras Energia Peru S.A. in the Talara area of Peru, to improve recoveries in a column of over 2,500 ft of shaly sands, with absolute permeabilities not higher than 1 md and with average well spacing already in the order of 20 Acre. The study included the design of the facilities to process and handle the incremental production.
Analyses confirm that a massive infill drilling program would significantly increase the production in a period of 4 years, from current 3,200 bopd. The study also identified the areas with best potential for infill drilling. Among the sub-products developed in the study were a new production database to facilitate the task of mapping and calculating volumetrics, and a new methodology to estimate average net pay thickness from limited log information. The approach and methodologies developed for this project can be used to give new life to mature oil provinces around the world.
During the first semester of 2007, the Kitina field production increased of 160% reaching a production level lost since early 2004. This was achieved with a variegate set of actions on different reservoirs: 1st) infilling the Kitina South culmination with the long reach and ultra deep well KTM-SM5, 2nd) a massive multistage hydraulic fracturing campaign carried out on the three wells draining the low permeability 3A reservoir and 3rd) with the sweep optimization of the reservoir 1A.
Pluripotent stem cells such as embryonic stem cells and induced pluripotent stem cells could be good sources for obtaining massive hematopoietic stem cells (HSC) and mature blood cells. Coculture with feeder cells and embryoid body formation are two major strategies to induce hematopoietic differentiation from pluripotent stem cells. Derivation of HSC with ability of reconstituting human hematopoiesis in immunodeficient mice has been achieved. It is also possible to generate mature blood cells such as neutrophils, erythrocytes, and platelets from pluripotent stem cells. Their morphologies, phenotypes, and functions are usually very similar to those of normal counterparts. However, a breakthrough is needed to overcome the issue of "yield", which still stands as a high barrier to reach clinical applications.
Collision tumor means the coexistence of two adjacent, buthistologically distinct tumors without histologic admixture in the sametissue and is rare incidence involving the ovary. There are instances ofcollision tumors consisting of teratoma with serous cystadenocarcinoma,mucinous cystadenocarcinoma, and/or granulosa cell tumor. The possibleexistence of an ovarian collision tumor should carefully be examined pre- andpost-operatively and histologically, so as to avoid misdiagnosis of apossible malignancy. We describe the findings in a histopathologically provencase of a massive mucinous cystadenoma and benign mature cystic teratomaarising in the same ovary.
After an exponential phase of growth, HK9 strain amebas, kept in the axenic medium PEHPS, spontaneously acquire a form morphologically similar to various natural cysts, as well as a resistance to hypotonic shock, due to the effect of a wall, partially composed of polysaccharides. The number of differentiated amebas increases gradually, although their viability diminishes, in function of the incubation time. On the ninth day, 96% of the population is made up of these cells, although only 6% are viable. The ultramicroscopic structure of the great majority of differentiated amebas corresponds to that of immature cysts. These, and the PEHPS medium, constitute a good model for a characterization of the start of the differentiation of E. histolytica, and open the opportunity of obtaining in axenic conditions, massive cultures of mature cysts. 041b061a72