Amortized Rotation Cost in AVL Trees

An AVL tree is the original type of balanced binary search tree. An insertion in an $n$-node AVL tree takes at most two rotations, but a deletion in an $n$-node AVL tree can take $\Theta(\log n)$. A natural question is whether deletions can take many rotations not only in the worst case but in the amortized case as well. A sequence of $n$ successive deletions in an $n$-node tree takes $O(n)$ rotations, but what happens when insertions are intermixed with deletions? Heaupler, Sen, and Tarjan conjectured that alternating insertions and deletions in an $n$-node AVL tree can cause each deletion to do $\Omega(\log n)$ rotations, but they provided no construction to justify their claim. We provide such a construction: we show that, for infinitely many $n$, there is a set $E$ of {\it expensive} $n$-node AVL trees with the property that, given any tree in $E$, deleting a certain leaf and then reinserting it produces a tree in $E$, with the deletion having done $\Theta(\log n)$ rotations. One can do an arbitrary number of such expensive deletion-insertion pairs. The difficulty in obtaining such a construction is that in general the tree produced by an expensive deletion-insertion pair is not the original tree. Indeed, if the trees in $E$ have even height $k$, $2^{k/2}$ deletion-insertion pairs are required to reproduce the original tree

Economics and Biodiversity in Intensively Managed Agro-Ecosystems

This paper explores the dynamic effects of biodiversity conservation on agricultural production in the context of specialised intensive farming systems. The focus is on the analysis of the dynamic effects of changes in the levels of agrobiodiversity, on technical change and productivity in intensive agricultural systems. A theoretical model is used to derive hypotheses regarding these linkages that are empirically tested using a stochastic production frontier model with data from a panel of UK cereal farms for the period 1989-2000. The results suggest that the increased agrobiodiversity has positively helped to shift the production frontier outwards. This indicates that the evolution of an intensive agricultural system to less intensive use of inputs can be consistent with non-decreasing output levels and an enhancement of biodiversity in agricultural landscapes.Agrobiodiversity, Intensive Agriculture, Productivity, Technical change, Resource /Energy Economics and Policy, Q12, Q16, Q24,

The Economics of Biodiversity Conservation in Agricultural Transition

This paper explores the dynamic effects of biodiversity conservation on agricultural production in the context of specialised intensive farming systems that may be in transition towards more sustainable farming. The focus is on the analysis of the dynamic effects of changes in the levels of agrobiodiversity, on technical change and productivity in intensive agricultural systems. A theoretical model is used to derive hypotheses regarding these linkages that are empirically tested using a stochastic production frontier model with data from a panel of UK cereal farms for the period 1989-2000. The results suggest that the increased agrobiodiversity has positively helped to shift the production frontier outwards. This indicates that agricultural transition from more to less intensive agricultural systems can be consistent with non-decreasing output levels and an enhancement of biodiversity in agricultural landscapes.agrobiodiversity, intensive agriculture, productivity, technical change, Environmental Economics and Policy, Q12, Q16, Q24,

Global Biofuel Expansion and the Demand for Brazilian Land: Intensification versus Expansion

We use a spatially disaggregated model of Brazilian agriculture to assess the implications of global biofuel expansion on Brazilian land usage at the regional level. This Brazilian model is part of the FAPRI agricultural modeling system, a multimarket, multi-commodity international agricultural model, used to quantify the emergence of biofuels and to analyze the impact of biofuel expansion and policies on both Brazilian and world agriculture. We evaluate two scenarios in which we introduce a 25% exogenous increase in the global demand for ethanol and one scenario in which we increase global ethanol demand by 50%. We then analyze the impact of these increases in terms of land-use change and commodity price changes particularly in Brazil. In the first scenario, we assume that the enforcement of the land-use reserve in Brazil remains at historically observed levels, and that abundant additional land can be readily incorporated into production. The second scenario involves implementing the same exogenous biofuel demand shock but with a different responsiveness in area expansion to price signals in Brazil, reflecting varying plausible assumptions on land availability for agricultural expansion. The third scenario, which is similar to the first scenario but with a larger increase in global ethanol demand, is run to check whether increasing volume of ethanol requires the incorporation of additional quantities of land per unit of ethanol. We find that, within Brazil, the expansion occurs mostly in the Southeast region. Additionally, total sugarcane area expansion in Brazil is higher than the increase in overall area used for agriculture. This implies that part of the sugarcane expansion displaced other crops and pasture that is not replaced, which suggests some intensification in land use. The lower land expansion elasticities in the second scenario result in a smaller expansion of area used for agricultural activities. A higher proportion of the expansion in sugarcane area occurs at the expense of pasture area, which implied land intensification of beef production. This explains the small change in commodity prices observed between the first and second scenarios. These results suggest that reducing the overall responsiveness of Brazilian agriculture may limit the land-use changes brought about by biofuel expansion, which would in turn reduce its environmental impacts in terms of land expansion. Additionally, the impacts on food prices are limited because of the ability of local producers to increase the intensity of land use in both crop (by double cropping and raising yields) and livestock production (by increasing the number of heads of cattle per hectare of pasture or stocking rate) releases area that can be used for crops. In scenario three, we find that larger ethanol volumes did not require more land per unit of ethanol. Doubling the demand for ethanol does not change the results, which indicates that the limit for intensification is beyond the 50% expansion assumed in Scenario 3. In this range, the same amount of land is incorporated into production per additional unit of ethanol.Biofuels, Brazil, land use, Land Economics/Use,

Discussion of “effect of exercise-induced dehydration on circulatory markers of oxidative damage and antioxidant capacity”

We read with great interest a recent article by Georgescu et al. (2017) entitled “Effect of exercise-induced dehydration on circulatory markers of oxidative damage and antioxidant capacity”. The authors aimed to investigate effects of hydration and rehydration by using sensitive indirect measures of oxidative stress and the antioxidant capacity response. In this study, they evaluated concentrations of plasma osmolality, Trolax equivalent antioxidant capacity (TEAC), and ferric reducing ability of plasma (FRAP) in a sample of athletes during pre-exercise, immediately postexercise, and 1 h after full rehydration. As stated in statistical analysis and also abstract of the article, the authors used 1-way ANOVA to compare differences in means of numerical variables (i.e., concentrations of plasma osmolality, TEAC, and FRAP) of different time-points of measurement. Since they investigated the same sample of participants in each group during different time-points (i.e., pre-exercise, immediately postexercise, and 1 h after full rehydration), their measurements are completely dependent (Farrokhi and Peykanpour 2017a; Farrokhi and Shirian 2017; Farrokhi et al. 2017). ANOVA and Kruskal–Wallis test are used for comparison of the means of more than 2 independent groups (Gaddis 1998; Farrokhi 2017b; Farrokhi and Arjaki 2017; Farrokhi and Peykanpour 2017b). Therefore, after assessment of the normal distribution of studied quantitative variables, including concentrations of plasma osmolality, TEAC, and FRAP, the authors must use repeated-measures ANOVA or Friedman test for comparison of the means of each variable at pre-exercise, immediately postexercise, and 1 h after full rehydration (Farrokhi 2017a; Farrokhi and Amani-Beni 2017). Furthermore, they must use Wilcoxon test and paired t test for comparison of concentrations of plasma osmolality, TEAC, and FRAP between 2 time-points of measurement

Manajemen dana zakat di Badan Amil Zakat daerah (BAZDA) kabupaten Kendal

Zakat sebagai rukun Islam yang ke tiga merupakan kewajiban setiap muslim yang mampu untuk membayarnya dan diperuntukkan bagi mereka yang berhak menerimanya. Pengelolaan yang baik zakat merupakan sumber dana potensial yang dimanfaatkan untuk memajukan kesejahteraan umum bagi seluruh masyarakat. Bulan Oktober 2012, Sebanyak 397.540 dari 1,2 juta jumlah warga di Kabupaten Kendal Jawa Tengah, tergolong miskin. Jumlah ini lebih banyak atau naik sekitar 40 persen, dibandingkan data terakhir pada tahun 2010. Kenaikan itu disebabkan banyaknya warga Kendal yang sudah tidak bekerja, karena ada putus hubungan kerja (PHK) yang dilakukan oleh pabrik tempatnya bekerja. Melihat kenyataan ini, maka aplikasi zakat perlu diterapkan apalagi mayoritas penduduk Indonesia beragama Islam. Namun di sisi lain, potensi zakat yang berhasil dihimpun oleh lembaga zakat masih jauh dari target. Hal ini menuntut adanya pengaturan dana yang professional sehingga potensi dana umat yang masih terbatas ini bisa dimanfaatkan secara optimal. Atas dasar inilah, penulis tertarik melakukan penelitian di Badan Amil Zakat Daerah (BAZDA) Kabupaten Kendal dengan tujuan untuk mengetahui manajemen dana di lembaga ini, baik dari aspek penghimpunan, pendistribusian, dan pendayagunaannya serta kendala-kendala yang dihadapi oleh Badan Amil Zakat ini. Metode analisis data yang digunakan dalam penelitian ini adalah analisis deskriptif kualitatif. Metode ini dipilih karena didasarkan atas desain penelitian, pendekatan penelitian serta sumber data yang digali sebagai data penelitian. Dalam penelitian ini dilakukan analisa antara teori yang sudah ada dengan realitas di lapangan, yaitu mengkaji bagaimana aplikasi manajemen pengelolaan dana zakat dan praktek pengelolaan yang ada di BAZDA Kendal mulai dari aspek penghimpunan, pendistribusian, dan pendayagunaan dana yang ada. Sumber data yang digunakan adalah data primer yaitu wawancara, dan data sekunder yaitu berupa buku-buku dan internet. Teknik pengumpulan dalam penelitian ini menggunakan wawancara dan dokumentasi. Hasil penelitian ini menunjukkan bahwa dari sisi penghimpunan di BAZDA Kabupaten Kendal Penghimpunan di BAZDA Kabupaten Kendal menggunakan Metode Fundraising Langsung (Direct Fundraising) yaitu mengirimkan pemberitahuan penghimpunan zakat melalui surat yang dikirim ke unit pengelola zakat (UPZ), telefundrising yaitu melalui via telephone dan presentasi langsung melalui kegiatan seminar dan sosialisasi. Metode Fundraising Tidak Langsung (Indirect fundraising) yaitu melalui perantara bank, melalui referensi dari berbagai instansi/perusahaan yang ada di Kendal dan mediasi para tokoh yang memiliki pengaruh dalam penghimpunan zakat. Pendistribusian zakat yang pertama dilakukan secara konsumtif yaitu penyaluran dana zakat yang di berikan langsung kepada mustahiq berupa paket sembako dan uang. Kedua, pendistribusian secara produktif (Pendayagunaan) diberikan dalam bentuk bantuan modal berupa pemberian pinjaman bergulir Rp 1.000.000 tanpa bunga dengan angsuran Rp 100.000 selama 9 kali untuk meningkatkan hasil usah

Diet composition and feeding habits of Acetes japonicus (Decapoda: Sergestidae) in estuarine waters of Tanjung Dawai, Kedah, Malaysia

This study describes the diet composition and feeding habits of sergestid shrimps Acetes japonicas. The stomach contents of 330 specimens, captured from the Estuary of Tanjung Dawai, Kedah from June 2008 - May 2009 were analysed. Analysis on the percentage of numerical abundance (Ci) showed that plant matter (28.18%) and crustacean appendages (18.70%) as the two highest values amongst the eight categories of feeding items. In addition, percentage frequency of occurrence (Fpi) values of phytoplankton, zooplankton, algae, plant matter, appendages of crustacean, debris, unidentified items and sand-mud were 3.54%, 7.05%, 5.07%, 27.44%, 17.42%, 15.80%, 8.94% and 19.81% respectively. Based on the food composition found in the stomach, it could be concluded that A. japonicus is a bottom feeder omnivorous

Sources of stress, coping strategies and counselling needs, among university students in Kingdom of Bahrain

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The aim of this study was: (1) to identify the main sources of stress that affect students' level of stress, students' coping strategies and their counselling needs. (2) To identify the relationship between sources of stress and coping strategies. (3) The effect of gender and Locality on sources of stress, level of stress, coping strategies and counselling needs. This study utilised both quantitative and qualitative research methods. Two hundred university students, represented by 80 female and 120 males, completed a constructed and standardised sources of stress questionnaire. A constructed and standardised questionnaire was used to measure students' needs for counselling. In addition, a translated and standardised Coping Strategies questionnaire by Lazarus and Folkman (1988) was used to measure the types of coping strategies used by the students. A translated standardised Perceived Stress questionnaire by Cohen et at (1983) was used to measure the level of stress. Reliability analysis revealed that the overall instrument demonstrated high reliability and validity. Findings revealed the different levels of importance that each source of stress and coping strategy was perceived to have had on students, this result indicated that students identified time management as the most frequent sources of stress, followed by religious and ethical, then the academic domains. The family domain was considered to be the source of least stress experienced by university students. In addition, the coping strategies reported to be used most by these students is accepting responsibility followed by positive reappraisal, then problem solving. Escape avoidance and distancing strategies were reported as less used strategies. It was found that financial issues had a significant effect on social support and problem solving coping strategies. Religion had a significant effect on the strategy of accepting responsibilities. Personal issues had a significant effect on the escape avoidance strategy. While, academic stress, in particular, has a significant effect on several coping strategies. Gender had a significant effect on level of stress from two sources of stress: Religious/Ethical and Personal stress, and one coping strategy: Escape avoidance. Females reported higher levels of stress, higher levels of sources of stress, and higher reported coping strategy use than males. Locality had a significant effect on counselling needs; Non- Homestudents experience more need for counselling than Home- students. Locality had a significant effect on. The mean use of coping strategies was greater for non- home students than Home- students. The results from this study suggest that university students do experience a significant level of stressful life events. Therefore, it is important that counsellors and teachers address the impact of stressful life events on a university student's well being. Conducting ongoing assessments of the level of stress experienced by university students might help counsellors or teachers intervene earlier and hence target better services to the population of students. Also, considering the unique sources for minority students, counsellors or teachers more appropriately should target unique interventions to meet their needs. The study also provides information that could help to reduce stress among university setting as it might be used as a reference point for counsellors, teachers, researcher when investigating university students stress and coping experience in Kingdom of Bahrain or any other Arabic country. The current constructed stress sources and counselling needs questionnaire could be also used by the researcher interested in this area.This study is funded by the University of Bahrain