Integration of Eucalyptus coppice regeneration with mechanical harvesting in South Africa

In South Africa, ca. 530 000 ha of the plantation area is planted to Eucalyptus spp. which are native to Australia. Commercially grown hardwoods account for 40.5% of the total area planted to trees, yet contribute more than 70% of the timber to the pulpwood market. This is largely attributed to the superior quality of fibre and pulping properties associated with eucalypt plantations, increases in global short-fibre pulp demands. This as well as the ability to reduce the temporary unplanted period and associated re-establishment costs when choosing to regenerate a stand through coppice management. With the unlikelihood of additional eucalypts being introduced into South Africa, and a reduction in genetic gains from 3rd-4th generation tree breading programmes, most of the eucalypts currently planted will be managed for at least one coppice rotation before replanting with improved genetic material if available. This together with the increased use of mechanised silvicultural and harvesting operations, concerns have been raised as to whether the integration of Eucalyptus coppice regeneration and mechanical harvesting in South Africa is both possible and financially viable for the forest industry to practise. The need for integration becomes more important as often mechanised systems have smaller tolerance levels when compared to manual systems. The first trial was situated in Zululand and was implemented to determine the type and severity of stump damage, coppicing potential and coppice growth over the rotation, associated with four types of harvesting and extraction systems on coppice regeneration. Results obtained from these four treatments (harvesting systems that ranged from manual to fully mechanised cut-to-length systems), found that irrespective of the harvesting system used, more damage occurred to the top than bottom half of the stump, with a significant decrease in coppice regrowth with increasing stump damage. Most damage and least coppice regrowth occurred in the extraction rows where the damage recorded could be attributed to vehicle movement, tear-outs and/or log stripping. There was no significant difference between the harvesting systems in terms of stump mortality, final stem stocking and rotation-end volume. Although this trial indicates that the harvesting systems tested had no impact on tree production the severity of damage and/or difference may have been masked by the excellent coppice potential of the species used for this trial (E. grandis x E. urophylla). Based on the results obtained in the first trial, and using five existing data sets, each data set consisted of four treatment sub-sets (4m_8m_s; 2m_8m_s; 4m_8m_BOP; 2m_8m_Or) where possible to determine the cost benefits associated with each treatment at various levels of stocking over a full rotation period. BOP (best operating practice) and Or (original stocking) refers to treatments with two stems stump-1, and s (single stem) refers to one stem stump-1. Within each of the four treatment sub-sets, treatments with three levels of stump survival were sought (60%; 80%; 100%), in order to assess financial viability of harvesting different coppice regimes (one coppice stem and two coppiced stems stump-1) using a fully mechanised cut-to-length harvesting system was tested. No differences were found between one coppice stem and two coppiced stems stump-1 in terms of financial returns (internal rate of return). Of the four treatment sub-sets (4m_8m_s; 2m_8m_s; 4m_8m_BOP; 2m_8m_Or), treatments which had two coppice stems stump-1 lead to increased harvesting cost, while coppice stumps with one stem favours mechanised harvesting and reduced harvesting costs. The final trial, which was also implemented in Zululand, tested the timing of reduction of one coppice stem stump-1 at various stump and stem densities in order to develop an appropriate coppice regime that could favour fully mechanised CTL harvesting systems. Although significant differences were detected at 23 months between the additional control (current recommendation) and the various Reduction_ht (3.5 m, 4.5 m, and 6.5 m) treatments for Dbh, Ba, and Stocking. It is likely that these differences may become less with time due to the decrease in absolute and relative differences between the various treatments with time. This thesis indicates that it is possible to successfully integrate eucalypt coppice regeneration and fully mechanised CTL harvesting. As the results obtained showed that despite the harvesting-associated damage found, no significant difference occurred between the harvesting systems tested in terms of stump mortality, stem stocking (after the final reduction) and rotation-end volume. With regards to the financial implications (using internal rates of return - IRR) associated with harvesting coppice stands of one or two stems stump-1, no clear cost-benefits were found between either of these two treatment scenarios. As those factors that contribute to increased volumes per hectare (increased stem numbers and the retention of two stems stump-1), tend to become normalised across a treatment sub-set, this results in increased harvesting costs with a reduction in the IRR. Coppice management regimes need to be investigated that favour fully mechanised CTL harvesting systems (fewer stems to harvest, but with increased volumes per stem). This includes a reduction to one stem stump-1, as opposed to the current recommendations where some stumps have two stems, such as was tested in the final trial. Although initial results were promising, rotation-end data would be needed to determine any longer term impacts from carrying out an early thinning of coppice shoots to one stem stump-1. Future research needs to be carried out to: determine the influence of mechanised harvesting and extraction for difference species of eucalypts, especially for those that do not coppice as well as the species tested in these trials (Eucalyptus grandis x Eucalyptus urophylla), develop harvesting productivity and/or volume models for coppiced stands of one and two stems stump-1 for different Eucalyptus spp., determine financial returns using specifically designed coppice management regimes which optimise the integration of both mechanical harvesting and silvicultural perations

Using transmission Kikuchi diffraction to characterise α variants in an α+β titanium alloy

Two phase titanium alloys are important for high-performance engineering components, such as aeroengine discs. The microstructures of these alloys are tailored during thermomechanical processing to precisely control phase fractions, morphology and crystallographic orientations. In bimodal two phase (α + β) Ti-6Al-2Sn-4Zr-2Mo (Ti-6242) alloys there are often three microstructural lengthscales to consider: large (∼10 μm) equiaxed primary α; >200 nm thick plate α with a basketweave morphology; and very fine scaled (<50 nm plate thickness) secondary α that grows between the larger α plates surrounded by retained β. In this work, we utilise high spatial resolution transmission Kikuchi diffraction (TKD, also known as transmission-based electron backscatter diffraction, t-EBSD) and scanning electron microscopy (SEM)-based forward scattering electron imaging to resolve the structures and orientations of basketweave and secondary α in Ti-6242. We analyse the α variants formed within one prior β grain, and test whether existing theories of habit planes of the phase transformation are upheld. Our analysis is important in understanding both the thermomechanical processing strategy of new bimodal two-phase titanium alloys, as well as the ultimate performance of these alloys in complex loading regimes such as dwell fatigue. Our paper champions the significant increase in spatial resolution afforded using transmission techniques, combined with the ease of SEM-based analysis using conventional electron backscatter diffraction (EBSD) systems and forescatter detector (FSD) imaging, to study the nanostructure of real-world engineering alloys

Unique transcriptomic landscapes identified in idiopathic spontaneous and infection related preterm births compared to normal term births.

Preterm birth (PTB) is leading contributor to infant death in the United States and globally, yet the underlying mechanistic causes are not well understood. Histopathological studies of preterm birth suggest advanced villous maturity may have a role in idiopathic spontaneous preterm birth (isPTB). To better understand pathological and molecular basis of isPTB, we compared placental villous transcriptomes from carefully phenotyped cohorts of PTB due to infection or isPTB between 28-36 weeks gestation and healthy term placentas. Transcriptomic analyses revealed a unique expression signature for isPTB distinct from the age-matched controls that were delivered prematurely due to infection. This signature included the upregulation of three IGF binding proteins (IGFBP1, IGFBP2, and IGFBP6), supporting a role for aberrant IGF signaling in isPTB. However, within the isPTB expression signature, we detected secondary signature of inflammatory markers including TNC, C3, CFH, and C1R, which have been associated with placental maturity. In contrast, the expression signature of the gestational age-matched infected samples included upregulation of proliferative genes along with cell cycling and mitosis pathways. Together, these data suggest an isPTB molecular signature of placental hypermaturity, likely contributing to the premature activation of inflammatory pathways associated with birth and providing a molecular basis for idiopathic spontaneous birth

Analysis of the GOES 6.7 micrometer channel observations during FIRE 2

Clouds form in moist environments. FIRE Phase II Cirrus Implementation Plan (August, 1990) noted the need for mesoscale measurements of upper tropospheric water vapor content. These measurements are needed for initializing and verifying numerical weather prediction models and for describing the environment in which cirrus clouds develop and dissipate. Various instruments where deployed to measure the water vapor amounts of the upper troposphere during FIRE II (e.g. Raman lidar, CLASS sonds and new cryogenic frost hygrometer on-board aircraft). The formation, maintenance and dissipation of cirrus clouds involve the time variation of the water budget of the upper troposphere. The GOES 6.7 mu m radiance observations are sensitive to the upper tropospheric relative humidity, and therefore proved extremely valuable in planning aircraft missions during the field phase of FIRE II. Warm 6.7 mu m equivalent black body temperatures indicate a relatively dry upper troposphere and were associated with regions generally free of cirrus clouds. Regions that were colder, implying more moisture was available may or may not have had cirrus clouds present. Animation of a time sequence of 6.7 mu m images was particularly useful in planning various FIRE missions. The 6.7 mu m observations can also be very valuable in the verification of model simulations and describing the upper tropospheric synoptic conditions. A quantitative analysis of the 6.7 mu m measurement is required to successfully incorporate these satellite observations into describing the upper tropospheric water vapor budget. Recently, Soden and Bretherton (1993) have proposed a method of deriving an upper tropospheric humidity based on observations from the GOES 6.7 mu m observations. The method is summarized in the next section. In their paper they compare their retrieval method to radiance simulations. Observations were also compared to ECMWF model output to assess the model performance. The FIRE experiment provides a unique opportunity to further verify the GOES upper tropospheric relative humidity retrieval scheme by providing (1) aircraft observations to cross-validate the calibration of the GOES 6.7 mu m channel, (2) accurate upper tropospheric water vapor concentrations for verification, and (3) veritical variability of upper tropospheric water vapor

Questions in, Knowledge iN?: A study of Naver’s question answering community

Large general-purposed community question-answering sites are becoming popular as a new venue for generating knowledge and helping users in their information needs. In this paper we analyze the characteristics of knowledge generation and user participation behavior in the largest question-answering online community in South Korea, Naver Knowledge–iN. We collected and analyzed over 2.6 million question/answer pairs from fifteen categories between 2002 and 2007, and have interviewed twenty six users to gain insights into their motivations, roles, usage and expertise. We find altruism, learning, and competency are frequent motivations for top answerers to participate, but that participation is often highly intermittent. Using a simple measure of user performance, we find that higher levels of participation correlate with better performance. We also observe that users are motivated in part through a point system to build a comprehensive knowledge database. These and other insights have significant implications for future knowledge generating online communities

Investigating well-being, work limitations and preferences for self-management education and peer support among younger people with hip and knee osteoarthritis: protocol for a cross-sectional study

Introduction:&nbsp;Osteoarthritis (OA) has traditionally&nbsp;been considered a condition of older age. However,&nbsp;younger people are also affected by hip and knee OA,&nbsp;often as a result of sporting and work-related injuries.&nbsp;As OA studies have generally focused on older&nbsp;individuals, little is known about the experience of&nbsp;younger adults with hip or knee OA who can face a&nbsp;distinct set of pressures including work responsibilities&nbsp;and parenting roles. This study aims to investigate&nbsp;well-being and work participation among younger&nbsp;people with hip or knee OA, as well as preferences for&nbsp;OA education and support.Methods and analysis: 200 people aged 20&ndash;55 years with a diagnosis of hip and/or knee OA will be&nbsp;recruited for this cross-sectional study. Participants will&nbsp;be recruited from three major public hospitals in the&nbsp;state of Victoria, Australia following screening of&nbsp;orthopaedic outpatient clinic lists and referrals, and&nbsp;through community-based advertisements. A study&nbsp;questionnaire will be mailed to all participants and&nbsp;written informed consent obtained. Validated measures&nbsp;of Health-Related Quality of Life (HRQoL), health status,&nbsp;psychological distress and work limitations will be used. Information on health services use will be collected,&nbsp;in addition to information on the perceived utility and&nbsp;accessibility of a range of existing and proposed&nbsp;education and peer support models. HRQoL data will be&nbsp;compared with Australian population norms using&nbsp;independent t tests, and associations between HRQoL,&nbsp;health status, psychological distress, work limitations&nbsp;and demographic factors will be evaluated using&nbsp;univariate and multivariate analyses. Data on the&nbsp;perceived utility and accessibility of education and peer&nbsp;support models will be analysed descriptively.&nbsp;Ethics and dissemination: Ethics approval for the&nbsp;study has been obtained. The study findings will be&nbsp;submitted to peer-reviewed journals and arthritis&nbsp;consumer organisations for broader dissemination, and&nbsp;presented at national and international scientific meetings.</div

Bounded-Angle Spanning Tree: Modeling Networks with Angular Constraints

We introduce a new structure for a set of points in the plane and an angle $\alpha$, which is similar in flavor to a bounded-degree MST. We name this structure $\alpha$-MST. Let $P$ be a set of points in the plane and let $0 < \alpha \le 2\pi$ be an angle. An $\alpha$-ST of $P$ is a spanning tree of the complete Euclidean graph induced by $P$, with the additional property that for each point $p \in P$, the smallest angle around $p$ containing all the edges adjacent to $p$ is at most $\alpha$. An $\alpha$-MST of $P$ is then an $\alpha$-ST of $P$ of minimum weight. For $\alpha < \pi/3$, an $\alpha$-ST does not always exist, and, for $\alpha \ge \pi/3$, it always exists. In this paper, we study the problem of computing an $\alpha$-MST for several common values of $\alpha$. Motivated by wireless networks, we formulate the problem in terms of directional antennas. With each point $p \in P$, we associate a wedge $W_p$ of angle $\alpha$ and apex $p$. The goal is to assign an orientation and a radius $r_p$ to each wedge $W_p$, such that the resulting graph is connected and its MST is an $\alpha$-MST. (We draw an edge between $p$ and $q$ if $p \in W_q$, $q \in W_p$, and $|pq| \le r_p, r_q$.) Unsurprisingly, the problem of computing an $\alpha$-MST is NP-hard, at least for $\alpha=\pi$ and $\alpha=2\pi/3$. We present constant-factor approximation algorithms for $\alpha = \pi/2, 2\pi/3, \pi$. One of our major results is a surprising theorem for $\alpha = 2\pi/3$, which, besides being interesting from a geometric point of view, has important applications. For example, the theorem guarantees that given any set $P$ of $3n$ points in the plane and any partitioning of the points into $n$ triplets, one can orient the wedges of each triplet {\em independently}, such that the graph induced by $P$ is connected. We apply the theorem to the {\em antenna conversion} problem