Heavy thinning of ponderosa pine stands: an Arizona case study (Research Paper/RMRS–RP–22)

Growth and structural changes in a mosaic of even-aged ponderosa pine (Pinus ponderosa) stands were studied for 25 years to determine the long-term impacts of a heavy thinning treatment to a basal-area level of 25 ft2/acre. Basal area and volume growth of these stands has increased since thinning and likely will continue to increase as the residual trees increase in size. Furthermore, future stand integrity should be maintained at relatively low-density levels. It is unlikely, however, that timber production could be sustained at this level. A more plausible scenario is to manage the watershed for other resource values available from ponderosa pine stands

Finite one dimensional impenetrable Bose systems: Occupation numbers

Bosons in the form of ultra cold alkali atoms can be confined to a one dimensional (1d) domain by the use of harmonic traps. This motivates the study of the ground state occupations $\lambda_i$ of effective single particle states $\phi_i$, in the theoretical 1d impenetrable Bose gas. Both the system on a circle and the harmonically trapped system are considered. The $\lambda_i$ and $\phi_i$ are the eigenvalues and eigenfunctions respectively of the one body density matrix. We present a detailed numerical and analytic study of this problem. Our main results are the explicit scaled forms of the density matrices, from which it is deduced that for fixed $i$ the occupations $\lambda_i$ are asymptotically proportional to $\sqrt{N}$ in both the circular and harmonically trapped cases.Comment: 22 pages, 8 figures (.eps), uses REVTeX

Genomic evidence for distinct carbon substrate preferences and ecological niches of Bathyarchaeota in estuarine sediments

Investigations of the biogeochemical roles of benthic Archaea in marine sediments are hampered by the scarcity of cultured representatives. In order to determine their metabolic capacity, we reconstructed the genomic content of four widespread uncultured benthic Archaea recovered from estuary sediments at 48% to 95% completeness. Four genomic bins were found to belong to different subgroups of the former Miscellaneous Crenarcheota Group (MCG) now called Bathyarchaeota: MCG-6, MCG-1, MCG-7/17 and MCG-15. Metabolic predictions based on gene content of the different genome bins indicate that subgroup 6 has the ability to hydrolyse extracellular plant-derived carbohydrates, and that all four subgroups can degrade detrital proteins. Genes encoding enzymes involved in acetate production as well as in the reductive acetyl-CoA pathway were detected in all four genomes inferring that these Archaea are organo-heterotrophic and autotrophic acetogens. Genes involved in nitrite reduction were detected in all Bathyarchaeota subgroups and indicate a potential for dissimilatory nitrite reduction to ammonium. Comparing the genome content of the different Bathyarchaeota subgroups indicated preferences for distinct types of carbohydrate substrates and implicitly, for different niches within the sedimentary environment

Mechanistic insights of Li+ diffusion within doped LiFePO4 from Muon Spectroscopy

The Li+ ion diffusion characteristics of V- and Nb-doped LiFePO4 were examined with respect to undoped LiFePO4 using muon spectroscopy (µSR) as a local probe. As little difference in diffusion coefficient between the pure and doped samples was observed, offering DLi values in the range 1.8–2.3 × 10−10 cm2 s−1, this implied the improvement in electrochemical performance observed within doped LiFePO4 was not a result of increased local Li+ diffusion. This unexpected observation was made possible with the µSR technique, which can measure Li+ self-diffusion within LiFePO4, and therefore negated the effect of the LiFePO4 two-phase delithiation mechanism, which has previously prevented accurate Li+ diffusion comparison between the doped and undoped materials. Therefore, the authors suggest that µSR is an excellent technique for analysing materials on a local scale to elucidate the effects of dopants on solid-state diffusion behaviour

A new approach to surgical management of tibial plateau fractures

Tibial plateau fractures (TPFs) are challenging, requiring complex open reduction and internal fixation (ORIF) and are often associated with complications including surgical site infections (SSIs). In 2007, we introduced a novel management protocol to treat TPFs which consisted of an angiosome- or perforator-sparing (APS) anterolateral approach followed by unrestricted weight bearing and range of motion. The primary aim of this retrospective study was to investigate complication rates and patient outcomes associated with our new management protocol. In total, 79 TPFs treated between 2004 and 2007 through a classic anterolateral surgical approach formed the "Classic Group"; while 66 TPFS treated between 2007 and 2013 formed the "APS Group". Fracture reduction, maintenance of reduction and patient-reported outcomes were assessed. There was a clinically important improvement in the infection incidence with the APS (1.5%) versus the Classic technique (7.6%) (1/66 versus 2/79 for superficial infections; 0/66 versus 4/79 for deep infections). Despite a more aggressive rehabilitation, there was no difference in the fracture reduction over time or the functional outcomes between both groups (p > 0.05). The APS anterolateral approach improved the rate of SSIs after TPFs without compromising fracture reduction and stabilisation. We continue to use this new management approach and early unrestricted weight bearing when treating amenable TPFs.Stuart A. Callary, Claire F. Jones, Karim Kantar ... Markus P. Baker, Dominic Thewlis, Gerald J. Atkins ... et al

Global Observations from PHOBOS

Particle production in Au+Au collisions has been measured in the PHOBOS experiment at RHIC for a range of collision energies. Three empirical observations have emerged from this dataset which require theoretical examination. First, there is clear evidence of limiting fragmentation. Namely, particle production in central Au+Au collisions, when expressed as $dN/d\eta'$ ($\eta' \equiv \eta-y_{beam}$), becomes energy independent at high energy for a broad region of $\eta'$ around $\eta'=0$. This energy-independent region grows with energy, allowing only a limited region (if any) of longitudinal boost-invariance. Second, there is a striking similarity between particle production in e+e- and Au+Au collisions (scaled by the number of participating nucleon pairs). Both the total number of produced particles and the longitudinal distribution of produced particles are approximately the same in e+e- and in scaled Au+Au. This observation was not predicted and has not been explained. Finally, particle production has been found to scale approximately with the number of participating nucleon pairs for $N_{part}>65$. This scaling occurs both for the total multiplicity and for high \pT particles (3 <\pT< 4.5 GeV/c).Comment: QM2002 plenary talk, 10 pages, 11 figure

Evidence of Final-State Suppression of High-p_T Hadrons in Au + Au Collisions Using d + Au Measurements at RHIC

Transverse momentum spectra of charged hadrons with ${p_{T} <}$ 6 GeV/c have been measured near mid-rapidity (0.2 $< \eta <$ 1.4) by the PHOBOS experiment at RHIC in Au + Au and d + Au collisions at ${\sqrt{s_{_{NN}}} = \rm {200 GeV}}$. The spectra for different collision centralities are compared to ${p + \bar{p}}$ collisions at the same energy. The resulting nuclear modification factor for central Au + Au collisions shows evidence of strong suppression of charged hadrons in the high-$p_{T}$ region (${>2}$ GeV/c). In contrast, the d + Au nuclear modification factor exhibits no suppression of the high-$p_{T}$ yields. These measurements suggest a large energy loss of the high-$p_{T}$ particles in the highly interacting medium created in the central Au + Au collisions. The lack of suppression in d + Au collisions suggests that it is unlikely that initial state effects can explain the suppression in the central Au + Au collisions.Comment: 3 pages, 4 figures, International Europhysics Conference on High Energy Physics EPS (July 17th-23rd 2003) in Aachen, German

Identified particles in Au+Au collisions at sqrt{s_NN} = 200 GeV

The yields of identified particles have been measured at RHIC for Au+Au collisions at sqrt{s_NN} = 200 GeV using the PHOBOS spectrometer. The ratios of antiparticle to particle yields near mid-rapidity are presented. The first measurements of the invariant yields of charged pions, kaons and protons at very low transverse momenta are also shown.Comment: 4 pages, 4 figures, Contribution to Quark Matter 2002, Nantes, France, July 200

Universal Behavior of Charged Particle Production in Heavy Ion Collisions

The PHOBOS experiment at RHIC has measured the multiplicity of primary charged particles as a function of centrality and pseudorapidity in Au+Au collisions at sqrt(s_NN) = 19.6, 130 and 200 GeV. Two kinds of universal behavior are observed in charged particle production in heavy ion collisions. The first is that forward particle production, over a range of energies, follows a universal limiting curve with a non-trivial centrality dependence. The second arises from comparisons with pp/pbar-p and e+e- data. N_tot/(N_part/2) in nuclear collisions at high energy scales with sqrt(s) in a similar way as N_tot in e+e- collisions and has a very weak centrality dependence. This feature may be related to a reduction in the leading particle effect due to the multiple collisions suffered per participant in heavy ion collisions.Comment: 4 Pages, 5 Figures, contributed to the Proceedings of Quark Matter 2002, Nantes, France, 18-24 July 200