The Bellamy-Knights equation gives three-dimensional unsteady axisymmetric incompressible vortex solutions that are disconnected from the known exact steady solutions. In this paper, by introducing a ...new parameter that allows a change of the time scale, the Bellamy-Knights equation is transformed into an integro-differential equation that continuously connects with the equation for steady vortices. The new equation is viewed as describing the one-dimensional motion of a particle under conserved and nonconserved forces and leads to new regular solutions, in which the particle initially undergoes almost sinusoidal oscillations around the minimum of potential followed by a very rapid approach to the extrema of the potential. The regular solutions distribute discretely in the space of boundary conditions and are classified into types that are specified by the pattern of sequence of small and large oscillations of the axial component of velocity. Extending the solutions to singular ones, the boundary conditions for solutions of the same type are shown to form a continuous one-dimensional set, which we call a branch. The set of branches forms dense self-similar patterns with accumulation points, some of which coalesce to a single point. In an arbitrary neighborhood of the accumulation or coalescent point, any two distinct boundary conditions whose distance in the space of boundary conditions is arbitrarily small give mutually distinctive solutions with a finite difference at some region of the spatial distance. This feature of the equations signifies the extreme sensitivity of inflowing vortex solutions to boundary conditions.
This paper is aimed at eliciting consistency conditions for the existence of unsteady incompressible axisymmetric swirling viscous Beltrami vortices and explicitly constructing solutions that obey ...the conditions as well as the Navier–Stokes equations. By Beltrami flow, it is meant that vorticity, i.e., the curl of velocity, is proportional to velocity at any local point in space and time. The consistency conditions are derived for the proportionality coefficient, the velocity field and external force. The coefficient, whose dimension is of length−1, is either constant or nonconstant. In the former case, the well-known exact nondivergent three-dimensional unsteady vortex solutions are obtained by solving the evolution equations for the stream function directly. In the latter case, the consistency conditions are given by nonlinear equations of the stream function, one of which corresponds to the Bragg–Hawthorne equation for steady inviscid flow. Solutions of a novel type are found by numerically solving the nonlinear constraint equation at a fixed time. Time dependence is recovered by taking advantage of the linearity of the evolution equation of the stream function. The proportionality coefficient is found to depend on space and time. A phenomenon of partial restoration of the broken scaling invariance is observed at short distances.
Recent advances in technological tools for massively parallel, high-throughput sequencing of DNA have enabled the comprehensive characterization of somatic mutations in a large number of tumour ...samples. In this Review, we describe recent cancer genomic studies that have assembled emerging views of the landscapes of somatic mutations through deep-sequencing analyses of the coding exomes and whole genomes in various cancer types. We discuss the comparative genomics of different cancers, including mutation rates and spectra, as well as the roles of environmental insults that influence these processes. We highlight the developing statistical approaches that are used to identify significantly mutated genes, and discuss the emerging biological and clinical insights from such analyses, as well as the future challenges of translating these genomic data into clinical impacts.
•Above ground biomass (AGB) and coarse woody debris (CWD) decreased with elevation.•Size of living trees and CWD decreased with elevation.•The decomposition rate was higher at higher elevations due ...to smaller CWD.•The ratio of CWD to AGB was lower at higher elevations.•Climate change may alter the balance between CWD and AGB with elevation.
In recent years, coarse woody debris (CWD) of deadwood has attracted attention as a long-term carbon pool for global warming problems. Environmental factors such as temperature and precipitation vary greatly with elevation. Hence, it is expected that the carbon storage by CWD varies with elevation. However, few studies have examined the abundance of CWD along elevations. Therefore, we investigated the abundance and decay classes of CWD, aboveground biomass (AGB) and aboveground net primary production (ANPP) of living trees along an elevational gradient (1600–2800 m above sea level) in subalpine coniferous forests, central Japan. AGB, ANPP and CWD decreased with increasing elevation. AGB at 2800 m was about 10% of that at 1600 m a.s.l. On the other hand, CWD at 2800 m was only 2.2% of that at 1600 m a.s.l. Thus, the ratio of CWD to AGB was lower at higher elevations. The relative frequency of small CWD increased with elevation. In addition, smaller CWD tended to decay less. The lower ratio of CWD mass to AGB at higher elevations was probably caused by smaller CWD because small CWD rapidly disappears via the high decomposition rate due to its high ratio of surface area to volume. Therefore, this study suggests that the importance of CWD relative to AGB for carbon storage decreases with elevation in subalpine forests. Climate change may alter the balance between CWD and AGB by changing ANPP and decomposition rates along elevation gradients.
It is important to develop a convenient method for predicting photosynthetic rates in cold regions such as high elevations. Dwarf pine Pinus pumila is a representative treeline species in Japan. In ...this study, we investigated how environmental factors affect diurnal and seasonal variations of the in situ photosynthetic rate of P. pumila. Five environmental factors (photosynthetic photon flux density PPFD, air temperature T
a
, soil temperature T
s
, vapor pressure deficit VPD, and soil water content SWC) were examined. Photosynthetic measurements were conducted for four needle ages at hourly intervals on fifteen days from July to October 2018. The net photosynthetic rate decreased with needle age and changed seasonally and diurnally for each needle age. The net photosynthetic rate showed unimodal patterns with T
a
, T
s
, and SWC. The seasonal and diurnal changes in the net photosynthetic rate were related to seasonal changes in the four environmental factors (PPFD, T
a
, T
s
, SWC); the net photosynthetic rate decreased in mid-summer when T
a
, T
s
, and PPFD were high due to a decrease in SWC. Seasonal and diurnal changes in net photosynthetic rates could be reproduced by the multiplicative model of the four environmental factors and needle age. Therefore, the photosynthetic rate of P. pumila can be explained and predicted using these environmental factors and needle age. This information will be useful for predicting the effects of climate change on the photosynthetic production of plants in cold regions.
Summary Background Therapy-related myeloid neoplasms are secondary malignancies that are often fatal, but their risk factors are not well understood. Evidence suggests that individuals with clonal ...haemopoiesis have increased risk of developing haematological malignancies. We aimed to identify whether patients with cancer who have clonal haemopoiesis are at an increased risk of developing therapy-related myeloid neoplasms. Methods We did this retrospective case-control study to compare the prevalence of clonal haemopoiesis between patients treated for cancer who later developed therapy-related myeloid neoplasms (cases) and patients who did not develop these neoplasms (controls). All patients in both case and control groups were treated at MD Anderson Cancer Center (Houston, TX, USA) from 1997 to 2015. We used the institutional medical database to locate these patients. Patients were included as cases if they were treated for a primary cancer, subsequently developed therapy-related myeloid neoplasms, and had available paired samples of bone marrow from the time of therapy-related myeloid neoplasm diagnosis and peripheral blood from the time of primary cancer diagnosis. Patients were eligible for inclusion as age-matched controls if they were treated for lymphoma, received combination chemotherapy, and did not develop therapy-related myeloid neoplasms after at least 5 years of follow-up. We used molecular barcode sequencing of 32 genes on the pretreatment peripheral blood samples to detect clonal haemopoiesis. For cases, we also used targeted gene sequencing on bone marrow samples and investigated clonal evolution from clonal haemopoiesis to the development of therapy-related myeloid neoplasms. To further clarify the association between clonal haemopoiesis and therapy-related myeloid neoplasm development, we also analysed the prevalence of clonal haemopoiesis in an external cohort of patients with lymphoma who were treated in a randomised trial of front-line chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone, with or without melatonin. This trial was done at MD Anderson Cancer Center between 1999 and 2001 (protocol number 98-009). Findings We identified 14 cases and 54 controls. Of the 14 cases, we detected clonal haemopoiesis in the peripheral blood samples of ten (71%) patients. We detected clonal haemopoiesis in 17 (31%) of the 54 controls. The cumulative incidence of therapy-related myeloid neoplasms in both cases and controls at 5 years was significantly higher in patients with clonal haemopoiesis (30%, 95% CI 16–51) than in those without (7%, 2–21; p=0·016). In the external cohort, five (7%) of 74 patients developed therapy-related myeloid neoplasms, of whom four (80%) had clonal haemopoiesis; 11 (16%) of 69 patients who did not develop therapy-related myeloid neoplasms had clonal haemopoiesis. In the external cohort, the cumulative incidence of therapy-related myeloid neoplasms at 10 years was significantly higher in patients with clonal haemopoiesis (29%, 95% CI 8–53) than in those without (0%, 0–0; p=0·0009). In a multivariate Fine and Gray model based on the external cohort, the presence of clonal haemopoiesis significantly increased the risk of therapy-related myeloid neoplasm development (hazard ratio 13·7, 95% CI 1·7–108·7; p=0·013). Interpretation Preleukaemic clonal haemopoiesis is common in patients with therapy-related myeloid neoplasms at the time of their primary cancer diagnosis and before they have been exposed to treatment. Our results suggest that clonal haemopoiesis could be used as a predictive marker to identify patients with cancer who are at risk of developing therapy-related myeloid neoplasms. A prospective trial to validate this concept is warranted. Funding Cancer Prevention Research Institute of Texas, Red and Charline McCombs Institute for the Early Detection and Treatment of Cancer, NIH through MD Anderson Cancer Center Support Grant, and the MD Anderson MDS & AML Moon Shots Program.
Homogenous distribution of the Sn phase in the Al–Sn alloy is beneficial for improved properties. However, the alloy has a metastable immiscibility gap that results in macrosegregation of phases in a ...usual casting. In the present study, the alloy with an actual composition of Al–20 wt% Sn–1 wt% Cu (referred to Al–20 wt% Sn hereafter for simplicity) was solidified in a static magnetic field when alternating current flowed through the alloy, from which electromagnetic vibration (EMV) was imposed upon the solidifying liquid. Solidified microstructures were observed and characterized in terms of the low-melting-point Sn phase. It was found that when EMV was imposed at the frequency of f = 100 Hz, the Sn phase could be refined and dispersed homogenously in the primary Al matrix, which formed a contrast with the continuous Sn network in a usual casting solidified without EMV imposition. The specimen with fine Sn dispersions had an improved elongation in tensile tests. The solidification mechanism was discussed in terms of the structure formation and solute distribution when EMV was imposed during directional solidification. The uncoupled movement between the primary Al solid solution phase and the surrounding liquid may breakdown the Sn liquid film into discrete segments and thus form isolated particles at the final solidification stage. Meanwhile, this uncoupled movement can induce forced fluid flow that can stir the melt to homogenize the solute distribution in the remaining liquid pool. The composition transition was considered when EMV was imposed. To better support our analysis on the chemical composition variation during EMV processing, optical microstructures and differential scanning calorimetry (DSC) profiles were supplemented from a continuously cast Al–7 wt% Si alloy billet. The results of the Al–20 wt% Sn and Al–7 wt% Si alloys demonstrate that the EMV technique should be quite effective and applicable in improving solidification structures and mechanical properties provided that it is proceeded under appropriate conditions.
The upper distribution limit of tall tree species Abies mariesii is the timberline in central Japan, and dwarf pine Pinus pumila dominates above the timberline to near the summit. My previous studies ...suggested that the main cause of the timberline formation is the increase in mortality due to strong wind in winter rather than low growth due to low summer temperature. This study evaluated how wind velocity affects timberline formation and if the altitude of timberline moves upward due to high thermal conditions, by using a lattice model. Increase in wind velocity throughout the altitude lowered the altitudes of upper distribution limits of the two species. On the contrary, prolonged growth period due to high thermal conditions increased the upper distribution limit of P. pumila, and the upper distribution limit of A. mariesii was hardly affected by the change of growth period. However, the upward shift of the upper distribution limit of P. pumila due to the prolonged growth period in the model would not be realistic because P. pumila had already distributed up to near the summit. This study concludes that A. mariesii is a superior competitor to P. pumila at low altitudes with low wind velocity, but dwarf pine P. pumila can dominate at higher altitudes because A. mariesii suffers severe mechanical damage due to strong wind in winter, and that the altitude of the timberline does not move upward even under high thermal conditions due to global warming.
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