Taxonomic history, comparative morphology, and variation in Astrophytum myriostigma and its subspecies tulense (Cactaceae)

Astrophytum myriostigma subsp. myriostigma and subsp. tulense are distinguished by both vegetative and reproductive characters. The stem of the nominotypical subspecies is broad and depressed becoming broadly cylindrical in age, reaching a known maximum height of ca. 52 cm. In subsp. tulense, the stem is relatively slen-der and columnar and can reach a maximum height of ca. 90 cm. Both taxa show variation in the angle and profile of the ribs. In the nominotypical subspecies, the ribs are usually obtuse with a rounded or angular profile, or moderately acute with an angular profile. In subsp. tulense, the ribs are typically moderately to very acute with an angular profile. There are exceptions to these generalities. Both taxa have a modal number of five ribs, and both have the tendency to insert additional ribs with age, although the tendency seems more pronounced in subsp. tulense. The flower of the nominotypical subspecies differs from that of subsp. tulense in having a significantly larger mean perianth diameter (P <= 0.01), a significantly higher mean number of stigma lobes (P <= 0.05), and more tepal rows (3–5 vs. 1–3). The color of the tepals is pale yellow to whitish yellow in subsp. tulense, but brighter yellow or golden yellow in the nominotypical subspecies. The seeds of the nominotypical subspecies are significantly larger (P <= 0.01) than the seeds of subsp. tulense. Morphological variation was studied in nine populations of the subsp. myriostigma and six populations of the subsp. tulense. The nominotypical subspecies displays rib angle and rib profile differences among individual plants within a population. Plants with a depressed stem and obtuse, rounded ribs are predominant at some localities. At other localities, plants with more moderately acute, angular ribs are predominant, or at least common. Populations of subsp. tulense show individual variation in stem morphology. The stem varies from attenuated (tapered) to non-attenuated and from relatively slender (diameter ca. 20% of height) to relatively broad (diameter ca. 77% of height). The plants from near Mama León and adjacent localities in Tamaulipas, have very robust stems and are the least typical of the columnar subspecies. The rela-tionships of this population to other columnar populations warrant further study. The population near Las Tablas, San Luis Potosí, shows considerable variation in the stem and rib morphology. Some plants resemble the nominotypical subspecies whereas others are similar morphologically to subsp. tulense. The perianth diameter is intermediate between those of the two subspecies. The evidence suggests that this is an area of past or ongoing hybridization between the two taxa; the question of hybridization warrants further investigation. Attenuated and non-attenuated stems are the result of differential rates of vertical and lateral growth due to cellular activity in the apical and lateral meristems, respectively. The attenuated (tapered) stem is produced by a gradually increasing lateral growth rate which remains slower than the vertical rate. A non-attenuated stem is produced by the lateral growth rate exceeding the vertical rate early in development, then stabilizing at some point and not surpassing the vertical rate.

Cytogenetic events in the endosperm of amphiploid Avena magna × A. longiglumis

This study analysed cytogenetic events occurring in the syncytial endosperm of the Avena magna H. C. Murphy & Terrell × Avena longiglumis Durieu amphiploid, which is a product of two wild species having different genomes. Selection through the elimination of chromosomes and their fragments, including those translocated, decreased the level of ploidy in the endosperm below the expected 3n, leading to the modal number close to 2n. During intergenomic translocations, fragments of the heterochromatin-rich C-genome were transferred to the D and Al genomes. Terminal and non-reciprocal exchanges dominated, whereas other types of translocations, including microexchanges, were less common. Using two probes and by counterstaining with DAPI, the A. longiglumis and the rare exchanges between the D and Al genomes were detected by GISH. The large discontinuity in the probe labelling in the C chromosomes demonstrated inequality in the distribution of repetitive sequences along the chromosome and probable intragenomic rearrangements. In the nucleus, the spatial arrangement of genomes was non-random and showed a sectorial-concentric pattern, which can vary during the cell cycle, especially in the less stable tissue like the hybrid endosperm.

Cytogenetic events in the endosperm of amphiploidAvena maroccana×A. longiglumis

This study analysed cytogenetic events occurring in the syncytial endosperm of theAvena maroccanaGand. ×Avena longiglumisDur. amphiploid, which is a product of two wild species having different genomes. Selection through the elimination of chromosomes and their fragments, including those translocated, decreased the level of ploidy in the endosperm below the expected 3n, leading to the modal number close to 2n. During intergenomic translocations, fragments of the heterochromatin-rich C-genome were transferred to the A and Al genomes. Terminal and non-reciprocal exchanges dominated, whereas other types of translocations, including microexchanges, were less common. Using two probes and by counterstaining with DAPI, theA. longiglumisand the rare exchanges between the A and Al genomes were detected by GISH. The large discontinuity in the probe labelling in the C chromosomes demonstrated inequality in the distribution of repetitive sequences along the chromosome and probable intragenomic rearrangements. In the nucleus, the spatial arrangement of genomes was non-random and showed a sectorial-concentric pattern, which can vary during the cell cycle, especially in the less stable tissue like the hybrid endosperm.

Application of VMD and Hilbert Transform Algorithms on Detection of the Ripple Components of the DC Signal

Accurate detection of ripple components of the direct-current (DC) signals is essential for evaluating DC power quality. In this study, the combination algorithm based on variational mode decomposition (VMD) and Hilbert transform (HT) is applied to detect and analyze the characteristics of the ripple components of the DC disturbance signals. Firstly, the optimal modal number of VMD algorithms is comprehensively determined by observing the center frequencies of the mode components and the Index of Orthogonality (IO) of mode components. Through utilizing the VMD algorithm, the DC disturbance signal is accurately decomposed into a series of amplitude modulation-frequency modulation (AM-FM) functions. Then, the HT algorithm is applied to each AM-FM function to obtain the corresponding instantaneous amplitude and frequency, and the characteristics of DC disturbance signal are determined. Some case studies are implemented to analyze the ripple components of the DC disturbance signal with the VMD-HT and empirical mode decomposition (EMD) algorithm. Finally, the experiment results of Gree Photovoltaic Cabin have verified the feasibility and effectiveness of the proposed combination VMD-HT algorithm by comparison with EMD and the window interpolation fast Fourier transform (WIFFT) algorithms.

On the seasonal variation in observed size distributions in northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years of data from Aspvreten, Sweden

Size-resolved aerosol trends were investigated based on a 17-year data set (2000–2017) from the rural background site Aspvreten located in southern Sweden (58.8∘ N, 17.4∘ E). Cluster analysis of the size distributions was performed to aid in the interpretation of the data. The results confirm previous findings of decreasing aerosol mass and number during the last decades as a result of reduced anthropogenic emissions in Europe. We show that both particle modal number concentration and size have substantially been reduced during the last 17 years. Negative trends in particle number concentration of about 10 cm−3 yr−1 are present for nuclei, Aitken, and accumulation modes. In total, integral particle number concentration has decreased by 30 %, from 1860 to ca. 1300 cm−3. The reduction in modal number concentration is accompanied by a decrease in modal size, and this decrease is largest for the accumulation mode (2 nm yr−1 or about 17 % for the whole period). These reductions have resulted in a decrease in submicron particle mass (< 390 nm) by more than 50 % over the period 2000–2017. These decreases are similar to observations found at other stations in northern Europe. Although all size classes show a downward trend as annual averages, we also show that observed trends are not evenly distributed over the year and that a rather complex picture emerges where both sign and magnitude of trends vary with season and size. The strongest negative trends are present during spring (accumulation mode) and autumn (Aitken mode). The strongest positive trends are present during summer months (Aitken mode). The combined trajectory and data analyses do not present evidence for an increase in new particle formation formed locally, although some evidence of increased new particle formation some distance away from the receptor is present. Observed aerosol size distribution data, together with an adiabatic cloud parcel model, were further used to estimate the change in cloud droplet concentration for various assumptions of updraught velocities and aerosol chemical composition. The results indicate a substantial increase in the atmospheric brightening effect due to a reduction in cloud reflectivity corresponding to 10 %–12 % reduction in cloud albedo over the period 2000–2017.

On the seasonal variation of observed size distributions in Northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years data from Aspvreten, Sweden

Size resolved aerosol trends were investigate based on a 17-year data set (2000–2017) from the rural background site Aspvreten located in southern Sweden (58.8° N, 17.4° E). Cluster analysis of the size distributions was performed to aid in the interpretation of the data. The results confirm previous findings of decreasing aerosol mass during last decades as a result of reduced anthropogenic emissions in Europe. We show that both particle modal number concentration and size substantially has been reduced during last decades. Negative trends in particle number concentration of about 10 cm−3 y−1 is present for nuclei, Aitken and accumulation modes. In total, integral particle number concentration has decreased by 30 %, from 1860 cm−3 to ca 1300 cm−3. This decrease is similar to observations found at other stations in Northern Europe. The reduction in modal number concentration is accompanied by a decrease in modal size, and this decrease is largest for the accumulation mode (2 nm y−1 or about 17 % for the whole period). These reductions have resulted in a decrease in submicron particle mass (

Hypodiploidy in Childhood Acute Myeloid Leukemia: A Retrospective Cohort Study within the International Berlin-Frankfurt-Münster Study Group

Background: Despite major improvements in survival, relapse is still a frequent and severe event in pediatric acute myeloid leukemia (AML). Cytogenetic abnormalities represent important predictors of outcome. Improved risk stratification encompassing the identification of novel cytogenetic subsets may allow refinements in treatment strategies and increase survival rates. Hypodiploidy, defined as a modal number (MN) below 46 chromosomes, is associated with an adverse outcome in pediatric acute lymphoblastic leukemia. In childhood AML, the predominant cause of hypodiploidy is loss of a sex chromosome accompanying t(8;21). The most commonly lost autosome is chromosome 7, associated with a poor prognosis. However, other chromosome losses in pediatric AML have not been independently explored. We aimed to investigate the occurrence, genetic characteristics, and prognostic impact of hypodiploidy in childhood AML. Methods: This study was conducted as a retrospective cohort study within the I-BFM-AML framework. Children 0-18 years of age diagnosed with de novo AML between January 2000 to December 2015 and a hypodiploid karyotype were eligible for inclusion. Patients with constitutional hypodiploidy, monosomy 7, composite karyotypes, and t(8;21) with loss of a sex chromosome were excluded. Cytogenetic review was performed according to International System for Human Cytogenetic Nomenclature. Hypodiploidy was considered clonal when occurring in at least three metaphases. The clone with the lowest MN defined the ploidy level. The log-rank test was applied for estimating difference in survival. Considering allografting in first complete remission (CR1) as a time-dependent event, the effect of stem cell transplantation (SCT) on overall survival (OS) was estimated by the Mantel-Byar method. Multivariate analyses included sex, complex karyotype (≥3 non-recurrent aberrations), FLT3-ITD mutation status, and white blood cell count as covariates. As all patients with FLT3-ITD mutations had same MN (MN=45) leading to a skewed imputation model, multiple imputation was not performed, and multivariate analyses included complete cases only (n=54). Results: Hypodiploidy was detected in 81/6,409 patients with full karyotyping from 14 collaborative study groups, yielding a frequency of 1.2% in childhood AML. The cohort displayed a balanced sex distribution (male/female: 42/39) and a median age of 6 (range: 0-17). MNs 45 (n=66), 44 (n=10) and 43 (n=5) were observed. No patient had MN below 43. Eight patients (9.8%) had chromosome loss as the only aberration. Forty-eight patients (59%) had a complex karyotype. Core-binding factor abnormalities were observed in three patients (3.7%). Four patients harbored FLT3-ITD mutations (9.3%, 54 tested). Median follow-time for patients alive was 4.5 years (range: 0.2-15.3). Five-year event-free survival (EFS) and OS were 34% (CI 95%: 23% - 45%) and 52% (CI 95%: 40% - 63%), respectively. Cumulative incidence of relapse was 50% with a median time-to-relapse of 0.8 years. Twelve out of 38 relapsed children (32%) were alive at the end of follow-up. Children with MN≤44 (n=15) had lower EFS (21%, CI 95%: 4% - 46%) and OS (33%, CI 95%: 10% - 59%) than children with MN=45 (n=66, EFS: 37%, CI 95%: 24% - 49%, OS: 56%, CI 95%: 42% - 68%). Crude hazard ratios (HR) for MN≤44 vs MN=45 were 1.8 (p=0.08) for EFS and 1.9 (p=0.1) for OS. After adjustment HRs increased to 4.9 (p=0.001) and 6.1 (p=0.003), respectively. Loss of chromosome Y (n=12) displayed a non-significant superior survival (EFS: 58%, OS: 75%). Poor survival rates were especially observed in monosomy 9 (n=11, EFS: 14%, OS 15%), 10 (n=5, EFS: 20%, OS: 20%), and 16 (n=5, EFS: 25%, OS: 25%), although not reaching statistical significance. Allogenic SCT did not offer any advantage in survival. For children receiving SCT in CR1 (n=18), crude HR for OS was 1.4, p=0.39. Multivariate analysis showed HR for OS at 1.5, p=0.42. Exclusion of children not reaching CR1 (n=7) did not significantly change HRs. This large international study reveals that hypodiploidy is rare in pediatric AML. Children with loss of chromosome 9, 10, or 16 all displayed unfavorable survival rates, whereas loss of chromosome Y did not have influence on prognosis. SCT in CR1 did not improve survival. Our results suggest that modal number has an impact on outcome and may be important for risk stratification. Disclosures No relevant conflicts of interest to declare.

The impact of root flexibility on the fundamental frequency of a restrained cantilever beam

This study presents the theoretical and experimental studies of the impact of root flexibility on the fundamental frequency of the free bending vibration of a uniform Euler–Bernoulli cantilever beam elastically restrained at the root. The dispersion relation between the natural frequency and modal number has been derived and solved numerically and approximately using the series method of the expansion in terms of the modal number. It is shown that the approximate solution is reduced to the empirical Dunkerley rule, which is sound not universally true. A commercial force sensor is used for the experimental detection of the effect of root flexibility on the fundamental frequency of bending vibrations of a cantilevered beam. The strip-shape specimen attached to the force sensor forms a cantilever beam restrained at the root against rotation and translation and it fundamental frequency is identified. The results of measurements for a series of industrial materials are compared with exact calculations and those predicted by Dunkerley’s formula and an excellent agreement is observed.