Using airborne lidar to discern age classes of cottonwood trees in a riparian area

Airborne lidar (light detecting and ranging) is a useful tool for probing the structure of forest canopies. Such information is not readily available from other remote sensing methods and is essential for modern forest inventories. In this study, small-footprint lidar data were used to estimate biophysical properties of young, mature, and old cottonwood trees in the San Pedro River basin near Benson, Arizona. The lidar data were acquired in June 2004, using Optech's 1233 ALTM during flyovers conducted at an altitude of 600 m. Canopy height, crown diameter, stem dbh, canopy cover, and mean intensity of return laser pulses from the canopy surface were estimated for the cottonwood trees from the data. Linear regression models were used to develop equations relating lidar-derived tree characteristics with corresponding field acquired data for each age class of cottonwoods. The lidar estimates show a good degree of correlation with ground-based measurements. This study also shows that other parameters of young, mature, and old cottonwood trees such as height and canopy cover, when derived from lidar, are significantly different (P < 0.05). Additionally, mean crown diameters of mature and young trees are not statistically different at the study site (P = 0.31). The results illustrate the potential of airborne lidar data to differentiate different age classes of cottonwood trees for riparian areas quickly and quantitatively. Copyright © 2006 by the Society of American Foresters

Composite fermions close to the one-half filling of the lowest Landau level revisited

By strictly adhering to the microscopic theory of composite fermions for the Landau-level filling fractions nu_e = p/(2 p + 1), we reproduce, with remarkable accuracy, the surface-acoustic-wave (SAW)-based experimental results by Willett and co-workers concerning two-dimensional electron systems with nu_e close to 1/2. Our results imply that the electron band mass m_b, as distinct from the composite fermion mass m_*, must undergo a substantial increase under the conditions corresponding to nu_e approximately equal to 1/2. In view of the relatively low aerial electronic densities n_e to which the underlying SAW experiments correspond, our finding conforms with the experimental results by Shashkin et al. [Phys. Rev. B 66, 073303 (2002)], concerning two-dimensional electrons in silicon, that signal sharp increase in m_b for n_e decreasing below approximately 2 x 10^{11} cm^{-2}. We further establish that a finite mean-free path l_0 is essential for the observed linearity of the longitudinal conductivity sigma_{xx}(q) as deduced from the SAW velocity shifts.Comment: 5 pages, 2 postscript figure

Charge response function and a novel plasmon mode in graphene

Polarizability of non-interacting 2D Dirac electrons has a 1/\sqrt{qv-\omega} singularity at the boundary of electron-hole excitations. The screening of this singularity by long-range electron-electron interactions is usually treated within the random phase approximation. The latter is exact only in the limit of N -> infinity, where N is the ``color'' degeneracy. We find that the ladder-type vertex corrections become crucial close to the threshold as the ratio of the n-th order ladder term to the same order RPA contribution is (\ln|qv-\omega|)^n/N^n$. We perform analytical summation of the infinite series of ladder diagrams which describe excitonic effect. Beyond the threshold, qv>\omega, the real part of the polarization operator is found to be positive leading to the appearance of a strong and narrow plasmon resonance.Comment: 4 pages, 3 figures,typos correcte

Riparian vegetation classification from airborne laser scanning data with an emphasis on cottonwood trees

The high point density of airborne laser mapping systems enables achieving a detailed description of geographic objects and the terrain. Growing experience indicates, however, that extracting useful information directly from the data can be difficult. In this study, small-footprint lidar data were used to differentiate between young, mature, and old cottonwood trees in the San Pedro River Basin near Benson, Arizona, USA. The lidar data were acquired in June 2003, using the Optech Incorporated ALTM 1233 (Optech Incorporated, Toronto, Ont.), during flyovers conducted at an altitude of 750 m. The lidar data were preprocessed to create a two-band image of the study site: a high-accuracy canopy altitude model band, and a near-infrared intensity band. These lidar-derived images provided the basis for supervised classification of cottonwood age categories, using a maximum likelihood algorithm. The results of classification illustrate the potential of airborne lidar data to differentiate age classes of cottonwood trees for riparian areas quickly and accurately. © 2006, Taylor & Francis Group, LLC. All rights reserved

An Approach to Conserve Gaza Architectural Heritage Through Digital Technology

Heritage is considered as one of the constituents that preserve culture and national identity of any community. This is because heritage is a witness of accumulating experiences of that community. During recent years, architectural styles have changed dramatically in our country. Modern and western styles of housing prevailed so much that the Palestinian heritage touches nearly disappeared. In addition, many of the historic buildings in Gaza City have been destroyed due to the lack of public awareness about the importance of this heritage. This situation created the need for restoring the inveterate Palestinian culture and heritage through 3D Visualizing of Architectural Heritage. Awareness of cultural heritage through publicizing the digitized simulation of this heritage by using virtual reality and 3D modelling and animation techni-ques would help in preserving it and achieving balanced environment which reflects both originality of past and modernity of contemporaneity

The relationship between problem-focused coping strategies and quality of life in schizophrenic patients

Background: Schizophrenia is a disorder with psychotic symptoms that severely affects personal performance. Assessing problem- focused strategies and quality of life (QoL) in patients with schizophrenia may help the clinicians to use appropriate interventions. This study was conducted to find the relationship between problem-focused coping strategies and quality of life in schizophrenic patients who referred to the clinic of Iran University of Medical Sciences in 2013. Methods: Non-random sampling was used in two stages (quota and convenience sampling). Data were collected through Demographic Questionnaire, 5-point Likert-type scale World Health Organization Quality of Life and Problem-Focused Strategies Standard Questionnaire. Four dimensions of QoL which were assessed among schizophrenic patients were as follows: Physical health, mental health, social relationships and environmental factors. Pearson correlation coefficient and regression were used for data analysis. Results: The highest mean score (Mean = 2.7) belonged to environmental factors and the lowest score to social relationships (Mean = 2.55). Overall, there was a significant direct relationship between the QoL and problem-focused coping strategies (p = 0.024, r = 0.319). Conclusion: The Schizophrenic patients who used more problem- focused coping strategies had better QoL. Therefore, it is important to take into account problem- focus coping strategies when treating the patients. The application of this research will be crucial to clinicians and healthcare executives

The Serological Findings of Parvo virus B19 and Neopterin Detection among Sickle cell Disease Patients and Blood Doners in the Kingdom of Bahrain

Introduction. Parvovirus B19 (PV B19) is a small, non-enveloped, ss DNA virus with an icosahedral capsid having a size of 18–26 nm. PV B19 transmits through respiratory droplets, blood transfusion and nosocomial infections that have also been documented recently. The virus targets the actively dividing Erythroid Progenitor Cells (EPCs) that are found in the human bone marrow, fetal liver and human umbilical cord. Methods. The study was particularly conducted on Sickle Cell Disease (SCD) patients and focuses on the determination of parvovirus B19 among Bahraini population by relying on their clinical status. The serological study of PV B19 was performed using Enzyme Linked Immunosorbent Assay (ELISA) technique and includes 150 SCD patientsand 100 healthy blood donors in which both males and females were employed. The samples were taken from the emergency unit of Salmania Medical Complex (SMC) and Ibrahim Khalil Kano Center (IKKC). Results. Of the 150 SCD patients, 100 were with vaso-occlusive crisis(VOC) and 50 non-vaso-occlusive crisis (NVOC). The three groups showed significantly higher percentages of PV B19 IgG but the percentage in SCD was relatively high compared to the control group of age-matched healthy donors – 70% of the VOC patients, 76% of the NVOC cases and 57% of blood donors were found to be IgG sero-positive. Discussion and Conclusion. PV B19 is a pathogenic virus and sometimes considered as life-threatening specifically for those individuals who have SCD due to which a risk of transient aplastic crisis increases. This virus is only associated with those patients whohave some hematological disorders such as hemolytic anemia and erythro-cytopenia. An effective screening test must be performed in the future to reduce the risk of PV B19 infection. Keywords: Aplastic Crisis, Seroprevalence, Bahraini Population, Genotypes, Vasoocclusive crisis, Neopteri

Pengaruh Octane Booster pada Bahan Bakar terhadap Konsumsi dan Daya untuk Motor Bensin 4 Tak 1 Silinder

Berkembangnya teknologi mesin kendaraan, maka tuntutan kebutuhan bahan bakar dengan nilai oktan tinggi untuk meningkatkan kinerja mesin semakin meningkat. Namun, apakah benar octane booster yang telah diproduksi oleh produsen A, B, C yang dijual di pasaran tersebut memang terbukti secara signifikan dapat mendongkrak nilai oktan gasoline dan meningkatkan kinerja mesin. Nilai oktan bahan bakar menentukan proses pembakaran di dalam ruang silinder, kecepatan reaksi pembakaran juga ditentukan dari nilai oktan bahan bakarnya. Dalam penelitian ini, akan dilihat bagaimana pengaruh octane booster penambah nilai oktan terhadap konsumsi bahan bakar dan daya kerja motor bensin 4 tak 1 silinder. Bahan bakar yang digunakan adalah premium murni, kemudian dengan penambahan 2 liter premium : ¼ octane booster, 2 liter premium : ½ octane booster dan 2 liter premium : 1 octane booster. Obyek yang di teliti adalah konsumsi bahan bakar dan daya yang dihasilkan sepeda motor Yamaha new vega ZR. Hasil dari penelitian ini adalah terhadap Daya, komposisi 2 liter premium : ¼ pil oktan booster memberikan pengaruh yang baik, hal ini terbukti dari hasil pengujian bahwa dengan komposisi 2 liter premium : ¼ pil oktan booster menghasilkan daya yang lebih tinggi dibandingkan dengan premium murni atau yang diberi campuran zat aditif (oktan booster) baik ½ pil maupun 1 pil. Terhadap konsumsi bahan bakar, komposisi 2 liter premium : ¼ pil oktan booster juga memberikan pengaruh yang baik, hal ini terbukti dari hasil pengujian bahwa konsumsi bahan bakar dengan komposisi 2 liter premium : ¼ pil oktan booster lebih rendah dibandingkan dengan premium murni atau yang diberi campuran zat aditif (oktan booster ) baik ½ pil maupun 1 pil. Dari seluruh hasil menunjukkan bahwa komposisi 2 liter premium : ¼ pil oktan booster memberikan pengaruh yang paling baik dalam meningkatkan daya mesin maupun menghemat konsumsi bahan bakar

Synchronization in Complex Systems Following the Decision Based Queuing Process: The Rhythmic Applause as a Test Case

Living communities can be considered as complex systems, thus a fertile ground for studies related to their statistics and dynamics. In this study we revisit the case of the rhythmic applause by utilizing the model proposed by V\'azquez et al. [A. V\'azquez et al., Phys. Rev. E 73, 036127 (2006)] augmented with two contradicted {\it driving forces}, namely: {\it Individuality} and {\it Companionship}. To that extend, after performing computer simulations with a large number of oscillators we propose an explanation on the following open questions (a) why synchronization occurs suddenly, and b) why synchronization is observed when the clapping period ($T_c$) is $1.5 \cdot T_s < T_c < 2.0 \cdot T_s$ ($T_s$ is the mean self period of the spectators) and is lost after a time. Moreover, based on the model, a weak preferential attachment principle is proposed which can produce complex networks obeying power law in the distribution of number edges per node with exponent greater than 3.Comment: 16 pages, 5 figure