Ett kalkylstöd för ekonomiska analyser av avverkningsåtgärder på beståndsnivå

Det finns ett behov av hjälpmedel i skogsbranschen som underlättar det dagliga beslutstagandet som personalen ställs inför. Detta kan vara datamodeller som simulerar och optimerar olika beslutstaganden på beståndsnivå eller på skogsinnehavsnivå. Inom ramen för detta arbete programmerades ett kalkylstöd i Microsoft Excel med verktyget Visual Basic ©. Kalkylstödet kopplades samman med den av Skogforsk publicerade produktionsmodellen ProdMod (Ekö 1985) via makron. Med dessa två program kan beståndsutveckling och åtgärder simuleras på beståndsnivå med tillväxt, avverkningsuttag samt avverkningskostnad och intäkter som utdata. Simuleringen kan göras från åtta meters beståndshöjd fram till och med slutavverkning, med tre avverkningsingrepp under omloppstiden. Den geografiska avgränsningen utgörs av Norra Skogsägarnas verksamhetsområde (Figur 1). Med kalkylstödet kan man simulera ett uttag av rundvirke, men också uttag av träddelar och GROT. Olika skötselalternativ kan testas och jämföras med varandra. Några saker som kan jämföras är avverkningskostnaden, intäkten, nuvärdet, avverkad volym och skogsbruksnettot. Ett test utfördes av kalkylstödet genom att de från kalkylstödet erhållna värdena jämfördes med verkliga värden från fyra stycken gallringar. Data hämtades från gallringsuppföljningar och avräkningar. Testet visade på ett medelfel på (10,5 %) vid gallring gällande nettot fritt vid väg. Medelfelet bör dock endast ses som en indikation då underlaget var väldigt litet. Testet visade att intäkterna avvek lite mellan det simulerade och verkliga utfallet (1,6 %) medan avverkningskostnaderna avvek desto mer (7,4 %). En trolig förklaring till detta är att intäkterna som angetts i kalkylstödet, ett slags medelvärden gällande kvalitetsklasser, stämmer bra överens med verkligheten och att variationerna var relativt små. En förklaring till skillnaderna är att timmerandelsfunktionen i modellen var överskattande på de testade gallringarna. Detta leder i sin tur till att det totala nettot blir högre i kalkylstödet. Avverkningskostnaderna visade på ett högre medelfel i testet. Alla gallringar utom en visade på för låga avverkningskostnader, vilket egentligen inte säger så mycket eftersom de flesta gallringarna hade samma medelstam i uttaget, och det är dessa kostnaderna baseras på, varför spridningen i testet blev dålig. Den andra parametern som kostnaderna baseras på är skotningsavståndet. Denna var svår att beräkna eftersom flera olika gallringstrakter på en fastighet hade slagits samman i avräkningarna vilket kan ha påverkat medelfelet för avverkningskostnaderna i testet. Det är viktigt att lägga till att de gallringar som ingick i testet var så kallade ”Kvalitets- gallringar”. Med kvalitetsgallring menas att träd tas ut i alla trädklasser och att gallringen utförs med inriktning på hög kvalitet i det kvarvarande beståndet. Om andra gallringsformer t.ex. höggallring eller låggallring hade testats kan resultatet ha sett annorlunda ut.There is a need for decision support tools in forestry which can help to lighten the burden of daily decision making that the staff has to make. This can be done by computer models that simulate and optimize different decisions at stand level or at forest holding level. Within the work presented here, a calculation support program was made for Microsoft Excel using the tool Microsoft Visual Basic©. The calculation support program was connected with a production model called ProdMod (Ekö 1985). With these two programs, stand development and thinnings and clear cutting can be simulated on a stand level, with growth and harvested volumes and costs and incomes as output data. The simulation of the stand can be done for trees from eight meters height, with three simulated harvests under the circulation time. The model is applicable within the geographic region covered by Norra Skogsägarna (Figure 1). With the calculation support program outtake of round wood can be simulated . It is also possible to test different kinds of biomass harvesting. The different silvicultural methods can be compared by the harvest cost, incomes, net present value, harvested volume or the net income from the harvest. The calculation support program was evaluated in a test. The simulated values from the calculation support program were compared with the stand data and economic outcomes from four real thinnings. The test showed an average error in calculation of 10.5% for net income. The average error in calculation should be seen only as an indication as the evaluation data set was small. The test showed that the incomes were quite similar between the simulated and the real thinnings, with a difference of 1.6%. The cost of the thinnings differs a bit more, by 7.4%. A reasonable explanation for this is that the incomes given in the calculation support program are an average over tree quality classes and seem to be quite close to the real ones. The difference in the values of incomes can partly be explained by the overestimate of the timber proportion in the model. That leads to a higher income in the calculation support program. The costs show a bigger difference in the test. All simulated thinnings but one showed to low costs, but this can only be applied to this particular average tree size due to all four thinnings having approximately the same average tree size at harvest. It is this parameter (tree size) on which the costs are based on in the model, and therefore the overall spread was poor in the test. Another parameter in the cost function is distance to road. In the test cases, several thinnings had been merged in the economic report which adds uncertainty to the real values of distance to road. The thinnings in the test were so called “Quality thinnings” which implies that the thinning is made with the aim to leave high quality trees in the stand. Other types of thinnings might have given other results

Evaluation-Function-based Model-free Adaptive Fuzzy Control

Designs of adaptive fuzzy controllers (AFC) are commonly based on the Lyapunov approach, which requires a known model of the controlled plant. They need to consider a Lyapunov function candidate as an evaluation function to be minimized. In this study these drawbacks were handled by designing a model-free adaptive fuzzy controller (MFAFC) using an approximate evaluation function defined in terms of the current state, the next state, and the control action. MFAFC considers the approximate evaluation function as an evaluative control performance measure similar to the state-action value function in reinforcement learning. The simulation results of applying MFAFC to the inverted pendulum benchmark verified the proposed scheme\u27s efficacy

Faktor-faktor yang Mempengaruhi Profitabilitas Lembaga Keuangan Mikro di Kecamatan Tandun Kabupaten Rokan Hulu

FAKTOR-FAKTOR YANG MEMPENGARUHI PROFITABILITAS LEMBAGA KEUANGAN MIKRO DI KECAMATAN TANDUN KABUPATEN ROKAN HUL

The impact of age on post-operative outcomes of colorectal cancer patients undergoing surgical treatment

BACKGROUND: the purpose of study was to evaluate the impact of age on outcomes in colorectal cancer surgery. METHODS: patients on hospital database treated for colorectal cancer during the period 1995 – 2002 were divided into two groups: Group 1 – patients of 75 years or older (n = 154), and Group 2 – those younger than 75 years (n = 532). RESULTS: In Group 1, for colon cancers, proximal tumors were significantly more common (23% vs. 13.5%, p < 0.05), complicated cases were more frequent (46 % vs. 33%, p = 0.002), bowel obstruction more common at presentation (40% vs. 26.5%, p = 0.001), and more frequent emergency surgery required (24% vs. 14%, p = 0.003). Postoperative overall morbidity was higher in the elderly group, but with no differences in surgical complications rate. Overall 5 year survival was 39% vs. 55% (p = 0.0006) and cancer related 5 year survival was 44% vs. 62% (p = 0.0006). Multivariate Cox analysis showed that age was not an independent risk factor for postoperative mortality. CONCLUSION: Preoperative complications and co-morbidities, more advanced disease, and higher postoperative nonsurgical complication rates adversely affect postoperative outcomes after surgery for colorectal cancer in the elderly

Observed communication skills: how do they relate to the consultation content? A nation-wide study of graduate medical students seeing a standardized patient for a first-time consultation in a general practice setting

<p>Abstract</p> <p>Background</p> <p>In this study, we wanted to investigate the relationship between background variables, communication skills, and the bio-psychosocial content of a medical consultation in a general practice setting with a standardized patient.</p> <p>Methods</p> <p>Final-year medical school students (N = 111) carried out a consultation with an actor playing the role of a patient with a specific somatic complaint, psychosocial stressors, and concerns about cancer. Based on videotapes, communication skills and consultation content were scored separately.</p> <p>Results</p> <p>The mean level of overall communication skills had a significant impact upon the counts of psychosocial issues, the patient's concerns about cancer, and the information and planning parts of the consultation content being addressed. Gender and age had no influence upon the relationship between communication skills and consultation content.</p> <p>Conclusion</p> <p>Communication skills seem to be important for final-year students' competence in addressing sensitive psychosocial issues and patients' concerns as well as informing and planning with patients being representative for a fairly complex case in general practice. This result should be considered in the design and incorporation of communication skills training as part of the curriculum of medical schools.</p

Conceptualization of category-oriented likelihood ratio: a useful tool for clinical diagnostic reasoning

<p>Abstract</p> <p>Background</p> <p>In the diagnostic reasoning process medical students and novice physicians need to be made aware of the diagnostic values of the clinical findings (including history, signs, and symptoms) to make an appropriate diagnostic decision. Diagnostic reasoning has been understood in light of two paradigms on clinical reasoning: <it>problem solving </it>and <it>decision making</it>. They advocate the reasoning strategies used by expert physicians and the statistical models of reasoning, respectively. Evidence-based medicine (EBM) applies <it>decision theory </it>to the clinical diagnosis, which can be a challenging topic in medical education.</p> <p>This theoretical article tries to compare evidence-based diagnosis with expert-based strategies in clinical diagnosis and also defines a novel concept <it>of category-oriented likelihood ratio (LR) </it>to propose a new model combining both aforementioned methods.</p> <p>Discussion</p> <p>Evidence-based medicine advocates the use of quantitative evidence to estimate the probability of diseases more accurately and objectively; however, the published evidence for a given diagnosis cannot practically be utilized in primary care, especially if the patient is complaining of a nonspecific problem such as abdominal pain that could have a long list of differential diagnoses. In this case, expert physicians examine the key clinical findings that could differentiate between broader categories of diseases such as organic and non-organic disease categories to shorten the list of differential diagnoses. To approach nonspecific problems, not only do the experts revise the probability estimate of specific diseases, but also they revise the probability estimate of the <it>categories of diseases </it>by using the available clinical findings.</p> <p>Summary</p> <p>To make this approach analytical and objective, we need to know how much more likely it is for a key clinical finding to be present in patients with one of the diseases of a specific category versus those with a disease not included in that category. In this paper, we call this value <it>category-oriented LR</it>.</p

Extrapulmonary tuberculosis, human immunodeficiency virus, and foreign birth in North Carolina, 1993 – 2006

<p>Abstract</p> <p>Background</p> <p>The proportion of extrapulmonary tuberculosis (EPTB) reported in the United States has been gradually increasing. HIV infection and foreign birth are increasingly associated with tuberculosis and understanding their effect on the clinical presentation of tuberculosis is important.</p> <p>Methods</p> <p>Case-control study of 6,124 persons with tuberculosis reported to the North Carolina Division of Public health from January 1, 1993 to December 31, 2006. Multivariate logistic regression was used to obtain adjusted odds ratios measuring the associations of foreign birth region and US born race/ethnicity, by HIV status, with EPTB.</p> <p>Results</p> <p>Among all patients with tuberculosis, 1,366 (22.3%) had EPTB, 563 (9.2%) were HIV co-infected, and 1,299 (21.2%) were foreign born. Among HIV negative patients, EPTB was associated with being foreign born (adjusted ORs 1.36 to 5.09, depending on region of birth) and with being US born, Black/African American (OR 1.84; 95% CI 1.42, 2.39). Among HIV infected patients, EPTB was associated with being US born, Black/African American (OR 2.60; 95% CI 1.83, 3.71) and with foreign birth in the Americas (OR 5.12; 95% CI 2.84, 9.23).</p> <p>Conclusion</p> <p>Foreign born tuberculosis cases were more likely to have EPTB than US born tuberculosis cases, even in the absence of HIV infection. Increasing proportions of foreign born and HIV-attributable tuberculosis cases in the United States will likely result in a sustained burden of EPTB. Further research is needed to explore why the occurrence and type of EPTB differs by region of birth and whether host genetic and/or bacterial variation can explain these differences in EPTB.</p

The role of entry screening in case finding of tuberculosis among asylum seekers in Norway

<p>Abstract</p> <p>Background</p> <p>Most new cases of active tuberculosis in Norway are presently caused by imported strains and not transmission within the country. Screening for tuberculosis with a Mantoux test of everybody and a chest X-ray of those above 15 years of age is compulsory on arrival for asylum seekers.</p> <p>We aimed to assess the effectiveness of entry screening of a cohort of asylum seekers. Cases detected by screening were compared with cases detected later. Further we have characterized cases with active tuberculosis.</p> <p>Methods</p> <p>All asylum seekers who arrived at the National Reception Centre between January 2005 - June 2006 with an abnormal chest X-ray or a Mantoux test ≥ 6 mm were included in the study and followed through the health care system. They were matched with the National Tuberculosis Register by the end of May 2008.</p> <p>Cases reported within two months after arrival were defined as being detected by screening.</p> <p>Results</p> <p>Of 4643 eligible asylum seekers, 2237 were included in the study. Altogether 2077 persons had a Mantoux ≥ 6 mm and 314 had an abnormal chest X-ray. Of 28 cases with tuberculosis, 15 were detected by screening, and 13 at 4-27 months after arrival. Abnormal X-rays on arrival were more prevalent among those detected by screening. Female gender and Somalian origin increased the risk for active TB.</p> <p>Conclusion</p> <p>In spite of an imperfect follow-up of screening results, a reasonable number of TB cases was identified by the programme, with a predominance of pulmonary TB.</p