Do enzyme activities during decomposition follow predicted patterns? A test of the conceptual model of litter decay.

Surprisingly, there remains a paucity of research examining specific interactions between the relationship between microbial community behavior and plant litter chemistry during decomposition. A more mechanistic understanding of the relationship between these drivers will ultimately help determine the trajectory of litter decomposition and the conditions in which soils serve as either a source or sink for atmospheric C. In order to examine these relationships, a laboratory incubation was established using _Acer saccharum_ litter and a sandy soil (< 1.5% organic matter). Extracellular enzyme activities ([BETA]-glucosidase, N-acetyl glucosaminidase, leucine-amino peptidase, acid phosphatase, phenol oxidase, and peroxidase) were monitored on a consistent basis along with instantaneous rates of carbon dioxide production, microbial biomass (carbon and nitrogen) and phospholipid fatty acid biomarkers (PLFA), and nitrogen and phosphorus availability. Microbial biomass and microbial respiration peaked within the first week of the experiment. This was likely due to the high availability of water soluble substrates early in decay that can be obtained without the production of extracellular enzymes. [BETA]-glucosidase (BG), N-acetyl glucosaminadase (NAG), and acid phosphatase activities increased quickly following the first week and peaked within the first month (at approximately 15% mass loss). Leucine amino peptidase was not detected during the incubation, which may be due to its strong positive correlation with soil pH, while other hydrolytic enzymes tend to track concentrations of soil organic matter. Phenol oxidase and peroxidase activities were not measurable until the second month of the experiment (> 25% mass loss), likely following the depletion of more labile substrates. A second increase in BG activity was observed between Days 83-111, which may be due to an increase in the availability of cellulose that was previously shielded by lignin, since oxidative enzyme activity was first detected on Day 68. We also observed some shifts in microbial PLFAs along with enzyme activities during decomposition. Prior to the increases in enzyme activity we observed a high proportion of PLFA 18:1[omega]7c, which is a bacterial biomarker. As enzyme activities increased, we observed a decrease in this biomarker and an increase in 18:2[omega]6,9c, a fungal biomarker that was correlated with BG and NAG activity. We did not observe any clear relationships between PLFAs and lignolytic enzyme activity, however. Overall, we observed a distinct functional shift in microbial substrate use that may be associated with either changes in composition of the microbial community or community shifts in enzyme production

A Stellar Census of the Tucana-Horologium Moving Group

We report the selection and spectroscopic confirmation of 129 new late-type (K3-M6) members of the Tuc-Hor moving group, a nearby (~40 pc), young (~40 Myr) population of comoving stars. We also report observations for 13/17 known Tuc-Hor members in this spectral type range, and that 62 additional candidates are likely to be unassociated field stars; the confirmation frequency for new candidates is therefore 129/191 = 67%. We have used RVs, Halpha emission, and Li6708 absorption to distinguish contaminants and bona fide members. Our expanded census of Tuc-Hor increases the known population by a factor of ~3 in total and by a factor of ~8 for members with SpT>K3, but even so, the K-M dwarf population of Tuc-Hor is still markedly incomplete. The spatial distribution of members appears to trace a 2D sheet, with a broad distribution in X and Y, but a very narrow distribution (+/-5 pc) in Z. The corresponding velocity distribution is very small, with a scatter of +/-1.1 km/s about the mean UVW velocity. We also show that the isochronal age (20--30 Myr) and the lithium depletion age (40 Myr) disagree, following a trend seen in other PMS populations. The Halpha emission follows a trend of increasing EW with later SpT, as seen for young clusters. We find that members have been depleted of lithium for spectral types of K7.0-M4.5. Finally, our purely kinematic and color-magnitude selection procedure allows us to test the efficiency and completeness for activity-based selection of young stars. We find that 60% of K-M dwarfs in Tuc-Hor do not have ROSAT counterparts and would be omitted in Xray selected samples. GALEX UV-selected samples using a previously suggested criterion for youth achieve completeness of 77% and purity of 78%. We suggest new selection criteria that yield >95% completeness for ~40 Myr populations.(Abridged)Comment: Accepted to AJ; 28 pages, 12 figures, 5 tables in emulateapj forma

Can Residential Build to Rent provide a profitable low risk investment option?

Purpose : Recently there has been a refocusing on the yields of investment assets. Accordingly, as risks to income yields rise, this research investigates how residential Build to Rent (BtR) may provide an effectively diversified portfolio. Emergence of this new investment sector requires a comparison between the rate of return of (BtR) and other asset classes. We seek to ascertain how BtR can be used by investors to reduce risk and provide diversification benefits within a mixedasset portfolio. Methodology:The research methodology adopted utilised secondary data produced by a reputable research organisation, coupled with personal interviews with major participants within the BtR sector. Findings: Diversification of assets within an investment portfolio reduces the total risk and volatility of an investment portfolio based upon the Markowitz (1952) Modern Portfolio Theory (MPT) model. Analysis of BtR performance against other traditional asset classes including traditional investment property, proved BtR a valuable inclusion, reducing risk and providing valuable returns. Discussion:Limited UK based research material on BtR as an investment option for institutions (and individuals), indicates its relatively short history as an investment option. Accordingly, some reliance was placed upon traditional private residential rental data. Despite this, the BtR investment asset in a mixed asset portfolio proved a source of l

Polarization in the Lagoon nebula

A V-band polarimetric survey of stars associated with the Lagoon nebula was conducted. The data were combined with existing photometric and spectroscopic observations in order to investigate the alignment of magnetic field lines with identifiable symmetry axes and to evaluate the nature of dust in the immediate vicinity. Although stars are not in general highly polarized, electric vectors align with the minor axis of the Lagoon nebula, perpendicular to the major axis of the spatial distribution of massive stars. The observations indicate that the collapse of the molecular cloud progenitor was inhibited along directions perpendicular to magnetic field lines. Considering the low polarization efficiency and the high ratio of total to selective extinction, smaller grains of intranebular dust appear to have been destroyed

Numerical modeling of the interstellar medium in galactic disks

We have been developing detailed hydrodynamic models of the global interstellar medium in the hope of understanding the mass and volume occupied by various phases, as well as their structure and kinematics. In our model, the gas is modeled by one fluid while representative Pop 1 stars are modeled by a second fluid. The two fluids are coupled in that the gas forms into stars at a rate given by a Schmidt law while stellar mass loss returns matter into the gas phase (on a time scale of 100 Myr). Also, the stars heat the gas through stellar winds and the gas cools through optically thin radiation. The time behavior of these two fluids is studied in two spatial dimensions with the Eulerian finite difference numerical hydrodynamic code Zen. The two spatial dimensions are along the plane of a disk (x, total length of 2 kpc) and perpendicular to the disk (z, total height of +/- 15 kpc) and a galactic gravitational field in the z direction, typical of that at the solar circle, is imposed upon the simulation; self-gravity and rotation are absent. For the boundary conditions, outflow is permitted at the top and bottom of the grid (z = +/- 15 kpc) while periodic boundary conditions are imposed upon left and right sides of the grid. As initial conditions, we assumed a gaseous distribution like that seen for the H1 by earlier researchers, although the results are insensitive to the initial conditions. We have run simulations in which the heating due to stars, parameterized as a stellar wind velocity, a, is varied from low (a = 150 km/s), to intermediate (a = 300 km/s), to high (a = 600 km/s). Since the intermediate case is roughly equivalent to the Galactic energy injection rate from supernovae, this summary will concentrate on results from this simulation

On NCQFT and dimensionless insertions

In these notes, we aim at a precise definition of the tree level action for the noncommutative scalar and gauge field theories on four-dimensional canonically deformed Euclidean space. As tools to achieve this goal we employ power counting and normalization conditions.Comment: 10 page

Semiclassical Strings in AdS_5 x S^5 and Automorphic Functions

Using AdS/CFT we derive from the folded spinning string ordinary differential equations for the anomalous dimension of the dual N=4 SYM twist-two operators at strong coupling. We show that for large spin the asymptotic solutions have the Gribov-Lipatov recirocity property. To obtain this result we use a hidden modular invariance of the energy-spin relation of the folded spinning string. Further we identify the Moch-Vermaseren-Vogt (MVV) relations, which were first recognized in plain QCD calculations, as the recurrence relations of the asymptotic series ansatz.Comment: 4 page

Berry-phase blockade in single-molecule magnets

We formulate the problem of electron transport through a single-molecule magnet (SMM) in the Coulomb blockade regime taking into account topological interference effects for the tunneling of the large spin of a SMM. The interference originates from spin Berry phases associated with different tunneling paths. We show that in the case of incoherent spin states it is essential to place the SMM between oppositely spin-polarized source and drain leads in order to detect the spin tunneling in the stationary current, which exhibits topological zeros as a function of the transverse magnetic field.Comment: 4 pages, Revtex 4, 4 EPS figure

The Association Between Pelvic Discomfort and Erectile Dysfunction in Adult Male Bicyclists.

BackgroundBicycle riding's impact on erectile function remains a topic of great interest given cycling's popularity as a mode of transportation and exercise.AimWe evaluated risk factors for sexual dysfunction in male cyclists with the primary intention of determining if genital/pelvic pain and numbness are associated with erectile dysfunction (ED).MethodsWe surveyed male cyclists using an online anonymous questionnaire. Cyclists were queried on their demographics, cycling experience, and sexual function using the Sexual Health Inventory for Men (SHIM). ED was diagnosed when a completed SHIM score was <22. Regression analysis was used to evaluate the risk of ED in men with genital/pelvic pain or numbness after riding. The survey was designed in the United States.OutcomesQuantitative characterization of cycling habits, onset and timing of genital pain and numbness, and SHIM score.ResultsA total of 1635 participants completed the survey. A majority of men were over the age of 50 (58%, 934/1,607), Caucasian (88%, 1,437/1,635), had been active cyclists for over 10 years (63%, 1,025/1,635) and used road bikes (97%, 1,578/1,635). Overall, 22%, 30%, and 57% of men reported ED, genital pain, and genital numbness, respectively. While controlling for cohort demographics, body mass index, cycling intensity and equipment, and medical comorbidities, no saddle characteristics were associated with the risk of developing genital numbness. However, men reporting penile numbness were at higher risk of reporting ED (odds ratio [OR] = 1.453, P = .048). In addition, quicker onset of numbness and resolution of numbness within a day was associated with impaired erectile function. For example, numbness occurring less than 1 hour after cycling had greater odds of leading to ED than numbness after 5 hours (OR = 2.002, P = .032). Similarly, genital pain occurring less than 1 hour (OR = 2.466, P = .031) after cycling was associated with higher ED risk.Strengths & limitationsStrengths include a large sample size of high-intensity cyclists and validated questionnaire use. Limitations include reliance on anonymous self-reported survey data and minimal inquiry into the riding preferences and terrain traversed by cyclists.ConclusionsPelvic pain and numbness are common complaints among male riders in the United States. Men with such complaints are more likely to also report ED especially if it occurs earlier in the ride. Although direction of causality and temporality are uncertain, alleviation of factors resulting in pelvic discomfort may reduce cycling's impact on sexual function. Such interventions are critical given that cycling for both active travel and aerobic exercise confers numerous health benefits. Balasubramanian A, Yu J, Breyer BN, et al. The Association Between Pelvic Discomfort and Erectile Dysfunction in Adult Male Bicyclists. J Sex Med 2020;17:919-929