The Alaska Arctic Vegetation Archive (AVA-AK)

The Alaska Arctic Vegetation Archive (AVA-AK, GIVD-ID: NA-US-014) is a free, publically available database archive of vegetation-plot data from the Arctic tundra region of northern Alaska. The archive currently contains 24 datasets with 3,026 non-overlapping plots. Of these, 74% have geolocation data with 25-m or better precision. Species cover data and header data are stored in a Turboveg database. A standardized Pan Arctic Species List provides a consistent nomenclature for vascular plants, bryophytes, and lichens in the archive. A web-based online Alaska Arctic Geoecological Atlas (AGA-AK) allows viewing and downloading the species data in a variety of formats, and provides access to a wide variety of ancillary data. We conducted a preliminary cluster analysis of the first 16 datasets (1,613 plots) to examine how the spectrum of derived clusters is related to the suite of datasets, habitat types, and environmental gradients. We present the contents of the archive, assess its strengths and weaknesses, and provide three supplementary files that include the data dictionary, a list of habitat types, an overview of the datasets, and details of the cluster analysis

Professionalism, Golf Coaching and a Master of Science Degree: A commentary

As a point of reference I congratulate Simon Jenkins on tackling the issue of professionalism in coaching. As he points out coaching is not a profession, but this does not mean that coaching would not benefit from going through a professionalization process. As things stand I find that the stimulus article unpacks some critically important issues of professionalism, broadly within the context of golf coaching. However, I am not sure enough is made of understanding what professional (golf) coaching actually is nor how the development of a professional golf coach can be facilitated by a Master of Science Degree (M.Sc.). I will focus my commentary on these two issues

Baryons: What, When and Where?

We review the current state of empirical knowledge of the total budget of baryonic matter in the Universe as observed since the epoch of reionization. Our summary examines on three milestone redshifts since the reionization of H in the IGM, z = 3, 1, and 0, with emphasis on the endpoints. We review the observational techniques used to discover and characterize the phases of baryons. In the spirit of the meeting, the level is aimed at a diverse and non-expert audience and additional attention is given to describe how space missions expected to launch within the next decade will impact this scientific field.Comment: Proceedings Review for "Astrophysics in the Next Decade: JWST and Concurrent Facilities", ed. X. Tielens, 38 pages, 10 color figures. Revised to address comments from the communit

The explosion energy of early stellar populations: the Fe-peak element ratios in low-metallicity damped Ly-alpha systems

The relative abundances of the Fe-peak elements (Ti–Zn) at the lowest metallicities are intimately linked to the physics of core-collapse supernova explosions. With a sample of 25 very metal poor damped Lyα systems (DLAs), we investigate the trends of the Fe-peak element ratios with metallicity. For nine of the 25 DLAs, a direct measurement (or useful upper limit) of one or more of the Ti, Cr, Co, Ni, Zn/Fe abundance ratios could be determined from detected absorption lines. For the remaining systems (without detections), we devised a new form of spectral stacking to estimate the typical Fe-peak element ratios of the DLA population in this metallicity regime. We compare these data to analogous measurements in metal-poor stars of the Galactic halo and to detailed calculations of explosive nucleosynthesis in metal-free stars. We conclude that most of the DLAs in our sample were enriched by stars that released an energy of ≲1.2 × 10^(51) erg when they exploded as core-collapse supernovae. Finally, we discuss the exciting prospect of measuring Fe-peak element ratios in DLAs with Fe/H < 1/1000 of solar when 30-m class telescopes become available. Only then will we be able to pin down the energy that was released by the supernovae of the first stars

Effect of sample stacking on resolution, calibration graphs and pH in capillary zone electrophoresis

For the determination of components present in samples at very low concentrations, large injection volumes have to be applied in order to introduce a detectable amount of the analytes in capillary zone electrophoresis (CZE). To obtain a good resolution, the sample analytes have to be concentrated in narrow bands and therefore sample stacking is often applied. Sample stacking can lead to an increase in the electroosmotic flow and extra peak broadening during the analysis, through which the gain in resolution will be lost. Further, the presence of different electrolytes in the capillary can cause pH shifts. In this paper a model is given for the calculation of migration times of components applying sample stacking, and the effects of sample stacking in CZE on resolution, calibration graphs and pH are discusse

Observations of thermokarst and its impact on boreal forests in Alaska, U.S.A.

Thermokarst is developing in the boreal forests of Alaska where ice-rich discontinuous permafrost is thawing. Thawing destroys the physical foundation (ice-rich soil) on which boreal forest ecosystems rest causing dramatic changes in the ecosystem. Impacts on the forest depend primarily on the type and amount of ice present in the permafrost and on drainage conditions. At sites generally underlain by ice-rich permafrost, forest ecosystems can be completely destroyed. In the Mentasta Pass area, wet sedge meadows, bogs, thermokarst ponds, and Iakes are replacing forests. An upland thermokarst site on the University of Alaska Campus consists of polygonal pattern of troughs and pits caused by thawing ice-wedge polygons. Trees are destroyed in corresponding patterns. In the Tanana Flats, ice rich permafrost supporting birch forests is thawing rapidly and the forests are being converted to minerotrophic floating mat fens. At this site, an estimated 83% of 2.6*10^5 ha was underlain by permafrost a century or more ago. About 42% of this permafrost has been influenced by thermokarst development within the last 1 to 2 centuries. Thaw subsidence at the above sites is typically 1 to 2 m with some values up to 6 m. Much of the discontinuous permafrost in Alaska is extremely warm, usually within 1 or 2 degrees C of thawing, and highly susceptible to thermal degradation. Additional warming will result in the formation of new thermokarst

Side of dental anomalies and taurodontism as potential clinical markers for cleft subphenotypes

Objective: The aim of this work was to investigate in more detail the dental clinical features that could serve to define subphenotypes of oral clefts. Design: Dental records of oral cleft subjects from a group of 164 cases were examined, and 157 were included in this study. In addition, 65 families with two or more siblings born with clefts and 30 control families were evaluated to determine whether dental phenotypes were sporadic. Type of oral cleft and dental phenotypes (tooth agenesis, supernumerary teeth, taurodontism, dental transposition, and microdontia) outside the cleft area were investigated. Association of dental anomalies with preferential subtypes of cleft (subphenotype) was assessed. Results: A total of 74 subjects presented at least one developmental dental anomaly. Tooth agenesis was the most common dental anomaly (28.6%), followed by taurodontism (15.2%). Supernumerary teeth were associated with cleft palate only (p = .05). The absence of maxillary left lateral incisors was significantly associated with unilateral right cleft lip (p = .02). Bilateral clefts were strongly associated with bilateral dental anomalies (p < 0.001). In the cleft lip and palate group, tooth agenesis was associated with dental transposition (p = .03) and with supernumerary teeth (p = .009). Subjects with oral clefts have a higher risk of tooth agenesis (odds ratio = 3.33; 95% confidence interval, 1.18 to 10.13) and taurodontism (odds ratio = 3.95; 95% confidence interval, 2.28 to 6.82). Tooth agenesis, microdontic upper lateral incisors, and supernumerary teeth were most commonly found in unaffected siblings and parents of children born with clefts in comparison with families with no family history of clefts (p = .01). Conclusion: The preferential associations between specific cleft types with dental phenotypes suggest dental anomalies can be used as clinical markers to define the subphenotype isolated cleft lip and palate