Number Ofn Research Articles

Rifampicin Resistance Associated with rpoB Mutations in Neisseria gonorrhoeae Clinical Strains Isolated in Austria, 2016 to 2020.

ABSTRACTDue to increasing rates of antimicrobial resistance (AMR) in Neisseria gonorrhoeae, alternative treatments should be considered. To assess rifampicin’s potential as a gonorrhea treatment, we used rpoB mutations to estimate rifampicin resistance in Austrian N. gonorrhoeae isolates. We found 30% of resistant isolates clustering in three main phylogenomic branches. Rifampicin resistance was associated with resistance to other antibiotics. Therefore, rifampicin cannot be recommended as an alternative gonorrhea treatment in Austria, even in combination therapy.IMPORTANCE Gonorrhea, caused by Neisseria gonorrhoeae, is one of the most common bacterial sexually transmitted infections. It is treated with antibiotics, but an increasing number of N. gonorrhoeae strains are resistant to currently used treatments. In this study, we explored the potential of rifampicin, another antibiotic, as a treatment option for gonorrhea. However, around 30% of Austrian N. gonorrhoeae strains investigated were already resistant to rifampicin, which would limit its benefit as a gonorrhea treatment.

Recruitment and zonation in a sub-Antarctic rocky intertidal community

This study presents for the first time the factors governing the recruitment in a rocky intertidal community of the Beagle Channel, Tierra del Fuego (54°51′S 68°29′W), Argentina. The aim of this study was to examine the effect of grazers and predators, free substrate availability and crustose coralline algae on the recruitment of the main sessile components of the intertidal:Notochthamalus scabrosus, Notobalanus flosculus, Mytilus chilensis, Perumytilus purpuratusandAulacomya atraat three intertidal levels. For barnacles, the probability of recruitment was higher with grazers, while the contrary was observed for bivalves. The number ofN. flosculusrecruits was higher with increased substrate availability, whileN. scabrosusrecruited more with reduced free substrate in the first sampling. Mussel recruitment was higher with reduced free substrate. The highest probability of recruitment ofN. scabrosuswas observed at the upper level. Notably, this probability and the recruits per plot were higher at the mid level under uncaged-ORP treatment than expected for the mid level. The probability of bivalve andN. flosculusrecruitment was higher at upper and lower levels, respectively. At the lower level, barnacle recruitment was higher on bare rock than on crustose coralline algae. Our results suggest that grazers increase the probability of barnacle recruitment, while the presence of sessile organisms enhances the density of mussel recruits. Almost no recruitment of bivalves was observed in ORPs over one year, showing that the secondary succession is slow in this environment.

Values of the Euler 𝜙-function not divisible by a given odd prime, and the distribution of Euler-Kronecker constants for cyclotomic fields

Let ϕ \phi denote Euler’s phi function. For a fixed odd prime q q we investigate the first and second order terms of the asymptotic series expansion for the number of n ⩽ x n\leqslant x such that q ∤ ϕ ( n ) q\nmid \phi (n) . Part of the analysis involves a careful study of the Euler-Kronecker constants for cyclotomic fields. In particular, we show that the Hardy-Littlewood conjecture about counts of prime k k -tuples and a conjecture of Ihara about the distribution of these Euler-Kronecker constants cannot be both true.

Privacy-aware location data publishing

This article examines a new problem of k -anonymity with respect to a reference dataset in privacy-aware location data publishing: given a user dataset and a sensitive event dataset, we want to generalize the user dataset such that by joining it with the event dataset through location, each event is covered by at least k users. Existing k -anonymity algorithms generalize every k user locations to the same vague value, regardless of the events. Therefore, they tend to overprotect against the privacy compromise and make the published data less useful. In this article, we propose a new generalization paradigm called local enlargement , as opposed to conventional hierarchy- or partition-based generalization. Local enlargement guarantees that user locations are enlarged just enough to cover all events k times, and thus maximize the usefulness of the published data. We develop an O ( H n )-approximate algorithm under the local enlargement paradigm, where n is the maximum number of events a user could possibly cover and H n is the Harmonic number of n . With strong pruning techniques and mathematical analysis, we show that it runs efficiently and that the generalized user locations are up to several orders of magnitude smaller than those by the existing algorithms. In addition, it is robust enough to protect against various privacy attacks.

A revision of theDrosera omissa/D. nitidulacomplex (Droseraceae) from south‐west Western Australia

TheDrosera omissa/D. nitidulacomplex is revised.Drosera omissais reinstated and found to be conspecific withD. ericksoniae, which is reduced to synonymy. The taxon corresponding to the type ofD. nitidulais determined andD. allantostigmaandD. leucostigmaare elevated from subspecific to specific rank.Drosera patens(known previously asD. nitidulasubsp. ‘omissa’ andD. nitidula‘var. ?’) is described as a new species. All five species are compared morphologically, described and illustrated. Cytological investigation found all species to have chromosome numbers ofn= 14 and 2n= 28, suggesting a base number ofx= 7 for the complex.

New chromosome numbers for Lasiopetaleae: Malvaceae s.l. (or Sterculiaceae)

Previously unpublished chromosome numbers of n = 10 are reported for species of Lasiopetaleae genera Lasiopetalum, Seringia and Guichenotia. Additional new chromosome numbers of n = 10 for species of Keraudrenia and Thomasia match published records for these genera and other Lasiopetaleae Lysiosepalum and Hannafordia. There is one count of n = 20 for Thomasia angustifolia which is interpreted as a polyploid number. New counts of n = 10 are recorded for species of Rulingia and Commersonia, traditionally included in Byttnerieae, but with affinities to Lasiopetaleae. Comparison of Lasiopetaleae chromosome numbers with other members of the subfamily Byttnerioideae and the closely related Grewioideae (Malvaceae s.l.) shows no clear evidence for a trend towards either reduction or increase in chromosome number within the groups.

Taxonomic revision of Hannafordia (Lasiopetaleae: Sterculiaceae (Malvaceae s.l.))

Taxonomic revision of the endemic Australian genus Hannafordia F.Muell. identified five taxa, including three recognised species, a new subspecies H. quadrivalvis F.Muell. subsp. recurva C.F.Wilkins and a new subspecific combination H. bissillii F.Muell. subsp. latifolia (E.Pritzel) C.F.Wilkins. Taxonomic descriptions, a key, distribution maps, illustrations, anatomical findings and seed and seedling morphology are presented. A chromosome number of n = 10 is the first published record for the genus.

On a density problem of Erdös

For a positive integer n, let P(n) denotes the largest prime divisor of n and define the set: 𝒮(x) = 𝒮 = {n ≤ x : n does not divide P(n)!}. Paul Erdös has proposed that |S| = o(x) as x → ∞, where |S| is the number of n ∈ S. This was proved by Ilias Kastanas. In this paper we will show the stronger result that .

On the Parity of Additive Representation Functions

Let A be a set of positive integers,p(A,n) be the number of partitions ofnwith parts in A, andp(n)=p(N,n). It is proved that the number ofn⩽Nfor whichp(n) is even is ⪢N, while the number ofn⩽Nfor whichp(n) is odd is ⩾N1/2+o(1). Moreover, by using the theory of modular forms, it is proved (by J.-P. Serre) that, for allaandmthe number ofn, such thatn≡a(modm), andn⩽Nfor whichp(n) is even is ⩾cNfor any constantc, andNlarge enough. Further a set A is constructed with the properties thatp(A,n) is even for alln⩾4 and its counting functionA(x) (the number of elements of A not exceedingx) satisfiesA(x)⪢x/logx. Finally, we study the counting function of sets A such that the number of solutions ofa+a′=n,a,a′∈A,a<a′ is never 1 for largen.

The voltammetric behavior of concanavalin a at bare silver electrode and analytical application

The voltammetric behavior of concanavalin A at the bare silver electrode is described. Cyclic voltammograms show a pair of well-defined redox peaks for concanavalin A in the medium of phosphate buffer(pH=7.0) with electrochemical reaction rate constant ofK2=0.053 s−1 and electron transfer number ofn=2. Moreover, both the oxidation currents and the reduction currents have linear relationship with concanavalin A concentrations in the range of 1.0×10−6∼2.0×10−5 mol/L, which can be used as an analytical method for determining concanavalin A concentration.

Dynamics of electronically excited alkali atoms in superfluid helium

By spectroscopic method, the excited-state dynamics of alkalis implanted in liquid4He were found to depend on the kind of atoms. A new model based on a quasi-molecule, “alkali-He N ” is presented, where He atoms are localized in a particular anisotropic configuration and the number ofN and locations depend on the fine-structure intervals. With this model, the mechanisms for various optical responses are discussed.

Fluorescence yields and molecular orientation of thin organic films: Vapor-Deposited Oligothiophenes ?3T??8T

The fluorescence quantum yields of vapor-deposited (VD) films of α-oligothiophenes,nT, with ring numbers ofn=3-8 and layer thicknesses ofd=3-50 nm were determined at room temperature andT=77 K and compared to the yields of dilute solutions and small (5T)x clusters. The yields of highly oriented ultrathin films are of the order of ΦF=5*10(-5)-1*10(-4). The yields increase strongly with the layer thickness and also upon cooling, but do not reach the values in dilute solution. The main nonradiative deactivation step S1 → T1 in solution was quantified by(1)O2 production, the yields of which systematically decrease withn from ΦF (3T) to 0.36 (6T), in contrast to the fluorescence yields, which increase from ΦF=0.01 (2T) to 0.40 (6T). In films or clusters the S1 → T1 deactivation step must be a very unimportant side reaction: neither(1)O2 nor any signal of triplet-triplet absorption could be positively identified.

On the exponent of the ideal class group of 𝑄(√-𝑑)

Let m ( d ) m(d) be the exponent of the ideal class group of Q ( − d ) {\mathbf {Q}}(\sqrt { - d} ) , we establish the bound m ( d ) ≫ log ⁡ d log ⁡ log ⁡ d m(d) \gg \frac {{\log d}}{{\log \log d}} for almost all the discriminants d by using uniform asymptotic formulas on the number of n ≤ x n \leq x for which there exists a prime less than s for which n is a quadratic residue.

The effect of nonnestmates on foraging trail caste ratios ofNasutitermes corniger (Isoptera: Termitidae)

The mean number of workers on foraging trails ofNasutitermes corniger Motschulsky decreases after the introduction of nonnestmate conspecifics or congeneric heterospecifics. The mean number of soldiers on foraging trais does not vary when nestmates, conspecific nonnestmates or heterospecific workers are introduced. When heterospecific soldiers are introduced to the trail, however, the number ofN. corniger soldiers increases. Consequently, the ratio of soldiers to workers increases. These findings demonstrate that the addition of nonnestmates temporarily alters caste ratios on foraging trails, representing a shift in the distribution of castes in response to environmental perturbation.

Integral matrices of fixed rank

Asymptotic formulæare derived for the number of n × m n \times m matrices of fixed rank k k with rational integral coefficients that are contained in a Euclidean ball of radius T T in R n × m {{\mathbf {R}}^{n \times m}} . It is assumed that n ⩾ m &gt; k ⩾ 1 n \geqslant m &gt; k \geqslant 1 are fixed, and the asymptotics are valid as T T tends to infinity. The methods used are elementary.

Effects of Grazing by Flagellates on Competition for Ammonium between Nitrifying and Heterotrophic Bacteria in Soil Columns

The enhanced mineralization of immobilized nitrogen by bacteriophagous protozoa has been thought to favor the nitrification process in soils in which nitrifying bacteria must compete with heterotrophic bacteria for the available ammonium. To obtain more insight into this process, the influence of grazing by the flagellate Adriamonas peritocrescens on the competition for ammonium between the chemolithotrophic species Nitrosomonas europaea and the heterotrophic species Arthrobacter globiformis in the presence of Nitrobacter winogradskyi was studied in soil columns, which were continuously percolated with media containing 5 mM ammonium and different amounts of glucose at a dilution rate of 0.007 h (liquid volumes). A. globiformis won the competition for ammonium. The grazing activities of the flagellates had two prominent effects on the competition between N. europaea and A. globiformis. First, the distribution of ammonium over the profile of the soil columns was more uniform in the presence of flagellates than in their absence. In the absence of flagellates, relatively high amounts of ammonium accumulated in the upper layer (0 to 3 cm), whereas in the underlying layers the ammonium concentrations were low. In the presence of flagellates, however, considerable amounts of ammonium were found in the lower layers, whereas less ammonium accumulated in the upper layer. Second, the potential ammonium-oxidizing activity of N. europaea was stimulated in the presence of flagellates. The numbers of N. europaea at different glucose concentrations in the presence of flagellates were comparable to those in the absence of protozoa. However, in the presence of flagellates, the potential ammonium-oxidizing activities were four to five times greater than those in the absence of protozoa.

Competition for Ammonium between Nitrifying and Heterotrophic Bacteria in Continuously Percolated Soil Columns

Although the absence of nitrate formation in grassland soils rich in organic matter has often been reported, low numbers of nitrifying bacteria are still found in these soils. To obtain more insight into these observations, we studied the competition for limiting amounts of ammonium between the chemolithotrophic ammonium-oxidizing species Nitrosomonas europaea and the heterotrophic species Arthrobacter globiformis in the presence of Nitrobacter winogradskyi with soil columns containing calcareous sandy soil. The soil columns were percolated continuously at a dilution rate of 0.007 h, based on liquid volumes, with medium containing 5 mM ammonium and different amounts of glucose ranging from 0 to 12 mM.A. globiformis was the most competitive organism for limiting amounts of ammonium. The numbers of N. europaea and N. winogradskyi cells were lower at higher glucose concentrations, and the potential ammonium-oxidizing activities in the uppermost 3 cm of the soil columns were nonexistent when at least 10 mM glucose was present in the reservoir, although 10 nitrifying cells per g of dry soil were still present. This result demonstrated that there was no correlation between the numbers of nitrifying bacteria and their activities. The numbers and activities of N. winogradskyi cells decreased less than those of N. europaea cells in all layers of the soil columns, probably because of heterotrophic growth of the nitrite-oxidizing bacteria on organic substrates excreted by the heterotrophic bacteria or because of nitrate reduction at reduced oxygen concentrations by the nitrite-oxidizing bacteria. Our conclusion was that the nitrifying bacteria were less competitive than the heterotrophic bacteria for ammonium in soil columns but that they survived as viable inactive cells. Inactive nitrifying bacteria may also be found in the rhizosphere of grassland plants, which is rich in organic carbon. They are possibly reactivated during periods of net mineralization.

Competition for Ammonium between Nitrifying and Heterotrophic Bacteria in Dual Energy-Limited Chemostats

The absence of nitrification in soils rich in organic matter has often been reported. Therefore, competition for limiting amounts of ammonium between the chemolithotrophic ammonium-oxidizing species Nitrosomonas europaea and the heterotrophic species Arthrobacter globiformis was studied in the presence of Nitrobacter winogradskyi in continuous cultures at dilution rates of 0.004 and 0.01 h. Ammonium limitation of A. globiformis was achieved by increasing the glucose concentration in the reservoir stepwise from 0 to 5 mM while maintaining the ammonium concentration at 2 mM. The numbers of N. europaea and N. winogradskyi cells decreased as the numbers of heterotrophic bacteria rose with increasing glucose concentrations for both dilution rates. Critical carbon-to-nitrogen ratios of 11.6 and 9.6 were determined for the dilution rates of 0.004 and 0.01 h, respectively. Below these critical values, coexistence of the competing species was found in steady-state situations. Although the numbers were strongly reduced, the nitrifying bacteria were not fully outcompeted by the heterotrophic bacteria above the critical carbon-to-nitrogen ratios. Nitrifying bacteria could probably maintain themselves in the system above the critical carbon-to-nitrogen ratios because they are attached to the glass wall of the culture vessels. The numbers of N. europaea decreased more than did those of N. winogradskyi. This was assumed to be due to heterotrophic growth of the latter species on organic substrates excreted by the heterotrophic bacteria.

Hybridization of chromosome-polymorphic populations of the inquiline ant,Doronomyrmex kutteri (Hym., Formicidae)

The workerless, inquiline ant,Doronomyrmex kutteri has isolated populations with a haploid chromosome number ofn=23 both in the Alps (Swiss and South Tyrolean Alps) and in Sweden, and a population withn=25 in southern Germany. Crossbreeding of sexuals from all populations proved successful. Backcrosses of F1-females with males from the parental populations produced F2-females, and hybrid males withn=23, 24, or 25 chromosomes. The chromosome polymorphism is not due to B-chromosomes. Probably then=25 karyotype originated from then=23 karyotype by two Robertsonian fissions (2 ¯M → 4 ¯A), since then=25 karyotype was found in only one of the populations. Diploid males occurred frequently in colonies from four out of five sites investigated.

A critical comparison ofGracilaria chilensis andG. sordida (Rhodophyta, Gracilariales)

Gracilaria chilensis Bird, McLachlanet Oliveira from Chile andG. sordida Nelson from New Zealand have been compared with respect to reproductive anatomy, chromosome number, interfertility, and organellar DNA restriction profiles. No differences were found in reproductive anatomy, which in these species is distinguished by deeptextorii-type spermatangial conceptacles and prominent tubular nutritive cells directed only to the floor of the cystocarp. The species share a chromosome number ofn = 24 and are readily interfertile. Electrophoretic profiles of organellar DNA digested with four different restriction endonucleases were virtually identical between the species except for bands that represented accompanying plasmids. However, previous research has indicated that the four plasmid bands inG. chilensis and the single one inG. sordida have a common origin. On these groundsG. chilensis andG. sordida are