Distribution, ecology and conservation status of Dionysia involucrata Zaprjag., an endangered endemic of Hissar Mts (Tajikistan, Middle Asia)

Dionysia involucrata Zaprjag. (Primulaceae) is known as critically endangered endemic species of Hissar Mountains in Tajikistan. It is reported from few localities mainly in Varzob River valley and its tributaries. The species inhabits steep or overhanging faces of granite rocks in narrow river gorges. During the research all known populations of D. involucrata were examined in respect of the habitat conditions and species composition of vegetation plots. We analyzed the population extent of the species in its range in Tajikistan and the main threats in order to assess its conservation status. The detrended correspondence analysis was performed on a matrix of 65 relevés and 49 species (vascular plants and mosses), to classify the phytocoenosis with domination of D. involucrata according to their floristic composition in relation to other petrophytic vegetation units. Using our field data regarding present extent of occurrence and area of occupancy we conclude that the threat category of D. involucrata should be reassessed from critically endangered to endangered. The species shows decline tendency in extent of occurrence, area of occupancy as well as in number of locations. The vegetation plots with domination of D. involucrata have relatively high level of separateness due to different species composition. We define the new association – Dionysietum involucratae – representing chasmophytic vegetation of submontane and montane zone in Middle Asia (ca. 1000–1600 m a.s.l.). The plots of Dionysietum involucratae were found mainly on granite rocks, on very steep or overhanging faces, on southwestern or southern exposition. The association is rather poor in species with inconsiderable contribution of mosses. Despite the diagnostic species, Campanula incanescens, Carex koshewnikowii and Scutellaria hissarica were the most abundant and frequent taxa within the researched patches of vegetation

Distribution, floristic structure and habitat requirements of the riparian forest community Populetum talassicae ass. nova in the Central Pamir-Alai Mts (Tajikistan, Middle Asia)

This paper discusses the floristic structure, distribution and habitat requirements of a new forest syntaxon, Populetum talassicae ass. nova. The potential range of the Populetum talassicae association comprises the central Pamir-Alai and Tian-Shan Mountains in Middle Asia. The biotope of this community comprises high mountain river valleys and shore zones of mountain lakes situ- ated at elevations between 2200 and 2750 m. Phytocoenoses of the Populetum talassicae association are characterized by a clear predominance in the tree layer of a characteristic species of the association ‒ Populus talassica. Shrubs are not so abundant; how- ever, the undergrowth layer of the community could reach up to 60% of the total cover, consisting mainly of Salix spp., Hipophaë rhamnoides, Lonicera stenantha, Juniperus semiglobosa and J. seravschanica. The herbaceous layer is quite rich and has about 20 species on average. Among associated species mainly meadow, rush and marsh taxa have been noted. Regarding the considerable cover of the meadow species, the association of Populetum talassicae has been classified as the Populetea laurifolio-suaveolentis syntaxon. A new plant alliance was proposed ‒ Populion talassicae all. nova with Pedicularis dolichorhiza and Astragalus tibetanus as diagnostic species. The described forest association is one of the rarest and most rapidly disappearing wood communities in Tajikistan, which means that special conservation attention is called for

Recent developments in scholarly publishing to improve research practices in the life sciences

This is the author accepted manuscript. The final version is available from Portland Press via the DOI in this record.We outline recent developments in scholarly publishing that we think will improve the working environment and career prospects for life scientists. Most prominently, we discuss two key developments. (1) Life scientists are now embracing a preprint culture leading to rapid dissemination of research findings. (2) We outline steps to overcome the reproducibility crisis. We also briefly describe other innovations in scholarly publishing, along with changes to open access mandates from funding agencies.John Templeton Foundatio

Self similar Barkhausen noise in magnetic domain wall motion

A model for domain wall motion in ferromagnets is analyzed. Long-range magnetic dipolar interactions are shown to give rise to self-similar dynamics when the external magnetic field is increased adiabatically. The power spectrum of the resultant Barkhausen noise is of the form $1/\omega^\alpha$, where $\alpha\approx 1.5$ can be estimated from the critical exponents for interface depinning in random media.Comment: 7 pages, RevTex. To appear in Phys. Rev. Let

New records to the flora of Uzbekistan (Middle Asia)

The Republic of Uzbekistan is a Central Asian country with rich native flora. The territory belongs to the Irano-Turanian region in the Ancient Mediterranean floristic subkingdom of Holarctic. The flora of Uzbekistan accounts over 4300 species of vascular plants including large numbers of endemic species, but the check-list is still incomplete. Presented here ten new records to the flora of Uzbekistan, were found during the field studies and examination of herbarium collections preserved at TASH

Pulse-shaped two-photon excitation of a fluorescent base analogue approaches single-molecule sensitivity

Fluorescent nucleobase analogues (FBAs) have many desirable features in comparison to extrinsic fluorescent labels, but they are yet to find application in ultrasensitive detection. Many of the disadvantages of FBAs arise from their short excitation wavelengths (often in the ultraviolet), making two-photon excitation a potentially attractive approach. Pentacyclic adenine (pA) is a recently developed FBA that has an exceptionally high two-photon brightness. We have studied the two-photon-excited fluorescence properties of pA and how they are affected by incorporation in DNA. We find that pA is more photostable under two-photon excitation than via resonant absorption. When incorporated in an oligonucleotide, pA has a high two-photon cross section and emission quantum yield, varying with sequence context, resulting in the highest reported brightness for such a probe. The use of a two-photon microscope with ultrafast excitation and pulse shaping has allowed the detection of pA-containing oligonucleotides in solution with a limit of detection of ∼5 molecules, demonstrating that practical single-molecule detection of FBAs is now within reach

The anatomical structure of leaf blade of the Siberian feather grasses (Poaceae: Stipa)

Results of studies of the anatomical structure of leaf blade of Siberian feather grasses are presented. A cross sections of leave blades were studied in 15 species: S. capillata, S. grandis, S. krylovii, S. baicalensis, S. praecapillata, S. consanguinea, S. orientalis, S. lessingiana, S. kirghisorum, S. dasyphylla, S. pennata, S. pulcherrima, S. zalesskii, S. glareosa, S. klemenzii. The following diagnostic characters were identified: relative height and degree of expressiveness of edges, quantity and type of veins, extent of development and arrangement of sclerenchyma as well as number and type of trichomes on the adaxial surface of leaves. Despite the uniformity of these features in many species within sections, they exhibit distinctive morphological patterns and have been proved to be taxonomically useful.В статье представлены результаты исследования анатомического строения листовой пластинки 15 видов сибирских ковылей: S. capillata, S. grandis, S. krylovii, S. baicalensis, S. praecapillata, S. consanguinea, S. orientalis, S. lessingiana, S. kirghisorum, S. dasyphylla, S. pennata, S. pulcherrima, S. zalesskii, S. glareosa, S. klemenzii. У исследованных видов были выявлены следующие диагностические признаки: относительная высота и степень выраженности ребер, их форма, количество и тип жилок, степень развития и расположение склеренхимы, количество и тип трихом на адаксиальной поверхности листьев. Несмотря на однородность этих признаков у многих видов в пределах секции, на секционном уровне они проявляют отличительные морфологические закономерности и имеют высокую таксономическую значимость

Dynamics of a ferromagnetic domain wall and the Barkhausen effect

We derive an equation of motion for the the dynamics of a ferromagnetic domain wall driven by an external magnetic field through a disordered medium and we study the associated depinning transition. The long-range dipolar interactions set the upper critical dimension to be $d_c=3$, so we suggest that mean-field exponents describe the Barkhausen effect for three-dimensional soft ferromagnetic materials. We analyze the scaling of the Barkhausen jumps as a function of the field driving rate and the intensity of the demagnetizing field, and find results in quantitative agreement with experiments on crystalline and amorphous soft ferromagnetic alloys.Comment: 4 RevTex pages, 3 ps figures embedde

Relative Reactivity of the Metal-Amido versus Metal-Imido Bond in Linked Cp-Amido and Half-Sandwich Complexes of Vanadium

Treatment of (η5-C5H4C2H4NR)V(N-t-Bu)Me (R = Me, i-Pr) and CpV(N-p-Tol)(N-i-Pr2)Me (Cp = η5-C5H5) with B(C6F5)3 or [Ph3C][B(C6F5)4] results in formation of the corresponding cations, [(η5-C5H4C2H4NR)V(N-t-Bu)]+ and [CpV(N-p-Tol)(N-i-Pr2)]+. The latter could also be generated as its N,N-dimethylaniline adduct by treatment of the methyl complex with [PhNMe2H][BAr4] (Ar = Ph, C6F5). Instead, the analogous reaction with the linked Cp-amido precursor results in protonation of the imido-nitrogen atom. Sequential cyclometalation of the amide substituents gave cationic imine complexes [(η5-C5H4C2H4NCR'2)V(NH-t-Bu)]+ (R' = H, Me) and methane. Reaction of cationic [(η5-C5H4C2H4NR)V(N-t-Bu)]+ with olefins affords the corresponding olefin adducts, whereas treatment with 1 or 2 equiv of 2-butyne results in insertion of the alkyne into the vanadium-nitrogen single bond, affording the mono- and bis-insertion products [(η5-C5H4C2H4N(i-Pr)C2Me2)V(N-t-Bu)]+ and [(η5-C5H4C2H4N(i-Pr)C4Me4)V(N-t-Bu)]+. The same reaction with the half-sandwich compound [CpV(N-p-Tol)(N-i-Pr2)]+ results in a paramagnetic compound that, upon alcoholysis, affords sec-butylidene-p-tolylamine, suggesting an initial [2+2] cycloaddition reaction. The difference in reactivity between the V-N bond versus the V=N bond was further studied using computational methods. Results were compared to the isoelectronic titanium system CpTi(NH)(NH2). These studies indicate that the kinetic product in each system is derived from a [2+2] cycloaddition reaction. For titanium, this was found as the thermodynamic product as well, whereas the insertion reaction was found to be thermodynamically more favorable in the case of vanadium.

Dynamics of a ferromagnetic domain wall: avalanches, depinning transition and the Barkhausen effect

We study the dynamics of a ferromagnetic domain wall driven by an external magnetic field through a disordered medium. The avalanche-like motion of the domain walls between pinned configurations produces a noise known as the Barkhausen effect. We discuss experimental results on soft ferromagnetic materials, with reference to the domain structure and the sample geometry, and report Barkhausen noise measurements on Fe$_{21}$Co$_{64}$B$_{15}$ amorphous alloy. We construct an equation of motion for a flexible domain wall, which displays a depinning transition as the field is increased. The long-range dipolar interactions are shown to set the upper critical dimension to $d_c=3$, which implies that mean-field exponents (with possible logarithmic correction) are expected to describe the Barkhausen effect. We introduce a mean-field infinite-range model and show that it is equivalent to a previously introduced single-degree-of-freedom model, known to reproduce several experimental results. We numerically simulate the equation in $d=3$, confirming the theoretical predictions. We compute the avalanche distributions as a function of the field driving rate and the intensity of the demagnetizing field. The scaling exponents change linearly with the driving rate, while the cutoff of the distribution is determined by the demagnetizing field, in remarkable agreement with experiments.Comment: 17 RevTeX pages, 19 embedded ps figures + 1 extra figure, submitted to Phys. Rev.