Mathematical modeling in cancer has been growing in popularity and impact since its inception in 1932. The first theoretical mathematical modeling in cancer research was focused on understanding ...tumor growth laws and has grown to include the competition between healthy and normal tissue, carcinogenesis, therapy and metastasis. It is the latter topic, metastasis, on which we will focus this short review, specifically discussing various computational and mathematical models of different portions of the metastatic process, including: the emergence of the metastatic phenotype, the timing and size distribution of metastases, the factors that influence the dormancy of micrometastases and patterns of spread from a given primary tumor.
The sediments of Woski Pond, Yosemite Valley in Yosemite National Park, record paleoenvironmental change spanning the last 1550 years. Closed conifer forest, consisting primarily of ponderosa pine, ...white fir, incense-cedar and Douglas-fir, existed around the pond until ca. 650 years ago. After 650 years ago more open canopy vegetation types such as oaks, sage and shrubs were found. Ethnographic records taken at the time of contact indicate that the aboriginal inhabitants regularly burned the Valley. The rapid decline in pine and increase in oak, coupled with elevated charcoal concentrations, indications of increased erosion and great expansion of aboriginal populations and cultural technologies are highly suggestive of vegetation manipulation for increased food resources by the early inhabitants of the Valley.These findings have implications for management of assumed natural vegetation types.
Selecting appropriate management for the fetus with bilateral congenital hydronephrosis depends on our ability to accurately assess the severity of existing renal damage and to predict the potential ...for recovery of renal and pulmonary function if the obstruction is relieved. We reviewed our experience with 20 fetuses with congenital bilateral hydronephrosis to determine the prognostic value of various criteria used to assess functional potential, including temporary catheter exteriorization to measure fetal urine output and composition. Based on autopsy, biopsy, or clinical outcome, ten fetuses were classified retrospectively as "poor function," and ten fetuses as "good function." The good function group could be distinguished from the poor function group by the following criteria: Amniotic fluid (AF) status at presentation (P less than .001), ultrasound appearance of the fetal kidneys (P less than .05), fetal urine sodium and chloride concentration and osmolarity (P less than .001), and hourly urine output (P less than .02), but not by fetal urine iothalamate excretion or potassium and creatinine concentrations (P greater than .05). Based on these results, we have identified prognostic criteria that accurately identify the fetus with "good function" from the fetus with "poor function." We also reviewed the clinical management of our last 12 unreported cases. Ten fetuses had undergone diagnostic catheter placement and in utero renal function testing. This led to placement of a therapeutic indwelling catheter-shunt in seven fetuses (three required multiple shunts) and a suprapubic vesicostomy in another. Catheter related complications, including three cases of chorioamnionitis, emphasize the need for better methods of in utero decompression in selected cases. Our ability to select appropriate management has improved markedly.
Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently ...to the lower respiratory tract. To investigate this issue, we exposed 15 healthy and 15 asthmatic volunteers in a controlled-environment chamber (21 degrees C, 50 percent relative humidity) to four test atmospheres: (i) clean air; (ii) 0.5-microns H2SO4 aerosol at approximately 100 micrograms/m3, generated from water solution; (iii) 0.5-microns carbon aerosol at approximately 250 micrograms/m3, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (iv) carbon as in (iii) plus approximately 100 micrograms/m3 of ultrafine H2SO4 aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (iv) became attached to carbon particle surfaces, and that most particles remained in the sub-micron size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation approximately 50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at end-exposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H2SO4 or carbon, separate or interactive, on health measures. Group data showed no more than small equivocal effects of any exposure on any health measure.
The relationship between the modern pollen rain and vegetation of alpine areas within the central Sierra Nevada in California is examined. Cluster analysis is used to help designate six major groups, ...corresponding to modern vegetation units. Abundant oak percentages characterize the oak grassland/woodland and chaparral. High oak and T-C-T (members of the Taxodiaceae-Cupressaceae-Taxaceae) distinguish the modern Sierra montane forest. Abundant pollen of red and white fir, with montane chaparral shrubs, characterize the upper Sierra montane and upper montane forests, while highest mountain hemlock pollen percentages are found in the subalpine forest. Sagebrush pollen dominates sites at most elevations east of the crest. Nonarboreal vegetation types are not distinguished palynologically in this cluster analysis, perhaps due to a paucity of samples. Pollen percentage limits for the local occurrence of a taxon are also established. Mountain hemlock and fir trees are absent at pollen percentages of less than 1% and 2 to 4%, respectively. At low elevations pine trees are absent when pollen percentages are 24% or less. The above results can be applied directly to studies of late Quaternary vegetation and climatic change of the area; most of the changes in past vegetation involved these taxa.
We present the discovery and characterisation of two transiting planets
observed by \textit{TESS} in the light curves of the young and bright (V=9.67)
star HD73583 (TOI-560). We perform an intensive ...spectroscopic and photometric
space- and ground-based follow-up in order to confirm and characterise the
system. We found that HD73583 is a young ($\sim 500$~Myr) active star with a
rotational period of $12.08 \pm 0.11 $\,d, and a mass and radius of $ 0.73 \pm
0.02 M_\odot$ and $0.65 \pm 0.02 R_\odot$, respectively. HD73583 b
($P_b=6.3980420 _{ - 0.0000062 }^{+0.0000067}$ d) has a mass and radius of
$10.2 _{-3.1}^{+3.4} M_\oplus$ and$2.79 \pm 0.10 R_\oplus$, respectively, that
gives a density of $2.58 _{-0.81}^{ 0.95} {\rm g\,cm^{-3}}$. HD73583 c ($P_c=
18.87974 _{-0.00074 }^{+0.00086}$) has a mass and radius of $9.7_{-1.7} ^
{+1.8} M_\oplus$ and $2.39_{-0.09}^{+0.10} R_\oplus$, respectively, this
translates to a density of $3.88 _{-0.80}^{+0.91} {\rm g\,cm^{-3}}$. Both
planets are consistent with worlds made of a solid core surrounded by a
volatile envelope. Because of their youth and host star brightness, they both
are excellent candidates to perform transmission spectroscopy studies. We
expect ongoing atmospheric mass-loss for both planets caused by stellar
irradiation. We estimate that the detection of evaporating signatures on H and
He would be challenging, but doable with present and future instruments.
