Arithmetic coding for data compression

Arithmetic coding provides an effective mechanism for removing redundancy in the encoding of data. We show how arithmetic coding works and describe an efficient implementation that uses table lookup as a first alternative to arithmetic operations. The reduced-precision arithmetic has a provably negligible effect on the amount of compression achieved. We can speed up the implementation further by use of parallel processing. We discuss the role of probability models and how they provide probability information to the arithmetic coder. We conclude with perspectives on the comparative advantages and disadvantages of arithmetic coding     

Distraction effects on muscle. Leg lengthening studied in rabbits

We investigated changes in the anterior tibial muscle during lengthening of the lower leg in rabbits. In 37 rabbits, an osteotomy of the right middle tibia was performed and was fixed by a unilateral external fixator. The rabbits were randomized into 6 groups. In groups 1, 2, and 3 the tibiae were distracted 0.5 mm/day. In groups 1 and 2, the rabbits were killed after 14 and 28 days of distraction, respectively, and in group 3 after 28 days of distraction, followed by 14 days of rest. Groups 1a, 2a, and 3a served as controls. They were treated similarly as groups 1, 2, and 3, but no distraction was performed. Proliferating cell nuclei were labeled with 5-bromo-2-deoxyuridine and were identified by immunohistochemical staining. The weight of the muscle was measured. During bone lengthening the muscle showed signs of growth, as indicated by increasing weight and number of proliferating cell nuclei. This was observed only during lengthening and it ceased when the lengthening was stopped.     

Isolated ovarian polyarteritis nodosa

Polyarteritis nodosa is a rare disorder and a form of systemic vasculitis. A 48 year-old female was admitted to the hospital because menorrhagia and pelvic pain in February 1993. The patient underwent exploratory laparotomy resulting in a total hysterectomy and bilateral salpingo-oophorectomy for myoma of uterus and a right adnexal cystic mass. Histopathologic examination revealed left ovarian periarteritis nodosa. Further investigation and 9 months follow-up failed to show any systemic involvement. To our knowledge the isolated ovarian polyarteritis nodosa is the first case in the literature.     

Temporal order and functional analysis of mutations within the Fli-1 and p53 genes during the erythroleukemias induced by F-MuLV

The erythroleukemias induced by Friend murine leukemia virus (F-MuLV) result from the accumulation of a number of genetic changes, including activation of the Fli-1 proto-oncogene and inactivation of the p53 tumor suppressor gene. We have determined the temporal order of mutation of the genes involved in this multistage malignancy, by serial in vivo transplantation of F-MuLV induced primary erythroleukemias into syngenic Balb/c mice. These primary tumors are capable of growing when transplanted into syngenic mice, but die after several days of in vitro culture. From the transplanted tumors grown in syngenic mice, erythropoietin-dependent cell lines were established in culture that are clonally related to cells in the primary tumors. We show that retroviral insertional activation of the Fli-1 ets family member is the first detectable genetic event in F-MuLV induced primary erythroleukemias. Mutations in the p53 gene were observed in the Epo-dependent cell lines but not in the transplanted erythroleukemias used to establish these cell lines in culture. These data suggest that activation of Fli-1 plays an important role in the early stages of F-MuLV-induced leukemia, perhaps by altering the self-renewal probabilities of erythroid progenitor cells and that p53 mutations immortalize these cells, enabling them to grow in vitro in the presence of Epo.     

Scanning electron microscopy of the myosin-coated surface of polystyrene beads in a force-movement assay system for ATP-dependent actin-myosin sliding

An outbreak of Cryptosporidiosis occurred over three months in a British Columbia community, peaking in December 1990. Results of the case-control study and illness surveys support the hypothesis that transmission occurred in a public children's pool at the local recreation centre. Analysis using lab-confirmed cases revealed a matched odds ratio of 4.5 [95% CI 0.97, 20.83], and using clinical cases an unmatched odds ratio of 12.8 [95% CI 3.68, 46.77], associated with swimming in the children's pool within two weeks prior to onset of illness. Other risk factors were not significant. Attack rates in various groups of children's pool users ranged from 8% to 78%. The children's pool was closed for steam cleaning and disinfection. Unusually frequent defecations including liquid stools had occurred before and during the outbreak. Improvements were instituted for removal of feces and superchlorination of pool water.     

Liquid viscosities and densities of HFC-134a+glycol mixtures

Liquid viscosity and density of six binary mixtures of HFC-134a with glycols [ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (400), and polypropylene glycol (2000)] have been measured in the temperature range from 273 to 333 K. The viscosity was measured by a rolling-ball viscometer calibrated with standard liquids of viscosities and densities (JS5, JS10, JS20, and JS50). The density was measured with a glass pycnometer. The uncertainties of the measurements were estimated to be less than 3.4 % for viscosity and 0.04 % for density, respectively. An equation is given to represent the obtained viscosity values as a function of weight fraction and temperature.     

Fetal heart rate following coelocentesis

For psychological reasons, coelocentesis was performed in 20 women prior to termination of pregnancy, at 6-11 weeks of gestation. The fetal heart rate (FHR) was measured immediately before the procedure and at 1, 5, and 10 min afterward. There was no significant difference between FHR before coelocentesis compared to the values at 1 min (mean = 158, range 114-178; z = -0.629, P = 0.529), 5 min (mean = 160, range 121-179; z = -0.191, P = 0.848), or 10 min (mean 159, range 117-183; z = -0.214, P = 0.83) after the procedure. These findings suggest that coelocentesis does not have a major effect on the fetal cardiovascular system.