On Computing the Average Distance for Some Chordal-Like Graphs

The Wiener index of a graph G is the sum of all its distances. Up to renormalization, it is also the average distance in G. The problem of computing this parameter has different applications in chemistry and networks. We here study when it can be done in truly subquadratic time (in the size n+m of the input) on n-vertex m-edge graphs. Our main result is a complete answer to this question, assuming the Strong Exponential-Time Hypothesis (SETH), for all the hereditary subclasses of chordal graphs. Interestingly, the exact same result also holds for the diameter problem. The case of non-hereditary chordal subclasses happens to be more challenging. For the chordal Helly graphs we propose an intricate O?(m^{3/2})-time algorithm for computing the Wiener index, where m denotes the number of edges. We complete our results with the first known linear-time algorithm for this problem on the dually chordal graphs. The former algorithm also computes the median set

A Study on Waterfowl Population and Human Use of Hokersar and Hygam Wetlands of Kashmir Valley for Conservation Planning

Not availabl

Proximity and Remoteness in Graphs: a survey

The proximity $\pi = \pi (G)$ of a connected graph $G$ is the minimum, over all vertices, of the average distance from a vertex to all others. Similarly, the maximum is called the remoteness and denoted by $\rho = \rho (G)$. The concepts of proximity and remoteness, first defined in 2006, attracted the attention of several researchers in Graph Theory. Their investigation led to a considerable number of publications. In this paper, we present a survey of the research work.Comment: arXiv admin note: substantial text overlap with arXiv:1204.1184 by other author

Habitat associations of the Coastal Giant Salamander (Dicamptodon Tenebrosus) at its northern range limit

Knowledge of species-environment associations is critical for the management of threatened amphibian populations facing habitat fragmentation and a restricted range. The Coastal Giant Salamander (Dicamptodon tenebrosus) is subject to habitat degradation from logging and human development and is classified as Threatened at its northern range limit in British Columbia, Canada. We examined habitat associations for D. tenebrosus in relation to relative abundance and presence/absence for 32 streams sampled across the approximately 100 km range of the species in British Columbia. Of 12 environmental variables we measured at 100-m stream reaches and the adjacent riparian zone, D. tenebrosus relative abundance was positively associated with stream elevation, forest age, and the percentage of boulders within streams. A higher stream gradient was the best predictor of D. tenebrosus presence within a stream reach, with present sites having a 91% higher gradient than absent sites. When excluding sites with low relative abundance, D. tenebrosus presence was also predicted by greater forest age surrounding streams and higher site elevation. Our study highlights that conservation planning for stream-associated amphibians with patchy distributions may be improved by an understanding of species-specific habitat associations at the stream-reach scale

Algorithms for Neural Prosthetic Applications

abstract: In the last 15 years, there has been a significant increase in the number of motor neural prostheses used for restoring limb function lost due to neurological disorders or accidents. The aim of this technology is to enable patients to control a motor prosthesis using their residual neural pathways (central or peripheral). Recent studies in non-human primates and humans have shown the possibility of controlling a prosthesis for accomplishing varied tasks such as self-feeding, typing, reaching, grasping, and performing fine dexterous movements. A neural decoding system comprises mainly of three components: (i) sensors to record neural signals, (ii) an algorithm to map neural recordings to upper limb kinematics and (iii) a prosthetic arm actuated by control signals generated by the algorithm. Machine learning algorithms that map input neural activity to the output kinematics (like finger trajectory) form the core of the neural decoding system. The choice of the algorithm is thus, mainly imposed by the neural signal of interest and the output parameter being decoded. The various parts of a neural decoding system are neural data, feature extraction, feature selection, and machine learning algorithm. There have been significant advances in the field of neural prosthetic applications. But there are challenges for translating a neural prosthesis from a laboratory setting to a clinical environment. To achieve a fully functional prosthetic device with maximum user compliance and acceptance, these factors need to be addressed and taken into consideration. Three challenges in developing robust neural decoding systems were addressed by exploring neural variability in the peripheral nervous system for dexterous finger movements, feature selection methods based on clinically relevant metrics and a novel method for decoding dexterous finger movements based on ensemble methods.Dissertation/ThesisDoctoral Dissertation Bioengineering 201

Technical Workshop: Advanced Helicopter Cockpit Design

Information processing demands on both civilian and military aircrews have increased enormously as rotorcraft have come to be used for adverse weather, day/night, and remote area missions. Applied psychology, engineering, or operational research for future helicopter cockpit design criteria were identified. Three areas were addressed: (1) operational requirements, (2) advanced avionics, and (3) man-system integration

오대산 국립공원 습지의 탄소 격리와 꿩고비의 서식지 특성

학위논문(석사) -- 서울대학교대학원 : 사범대학 과학교육과(생물전공), 2023. 2. 김재근.산지습지는 높은 생물다양성과 탄소 격리 기능을 가지고 있는 생태계이다. 하지만 현재 기후변화와 인간의 교란은 습지건조화를 일으켜 탄소격리 기능을 약화시키고 습지식물의 서식지를 단편화하고 있다. 오대산국립공원 습지는 우리나라를 대표하는 산지습지이며 람사르 보존법에 의해 보호받고 있다. 본 연구의 목적은 오대산 국립공원 산지습지의 탄소격리 기능을 평가하고, 산지습지의 우점식물인 꿩고비(Osmundastrum cinnamomeum)의 분포를 조사하여 최종적으로 산지습지의 보전을 강조하는 것이다. 이를 위해 다음과 같은 연구를 진행하였다. 첫째, 오대산 국립공원의 산지습지에서 탄소격리율과 탄소저장량을 추정하였다. 탐침봉을 사용하여 3개의 습지에서 유기층의 깊이를 측정하고 서로 다른 우점식물종을 가진 4개의 지역에서 12개의 코어를 수집하였다. 코어의 물리화학적 특성을 분석하였고, 4개의 코어는 constant rate of supply model을 사용한 210Pb분석을 통해 연대를 측정하였다. 토양의 물리화학적 분석과 210Pb 연대 측정을 기반으로 탄소 격리율과 탄소 저장량은 각각 58.29–125.31 g C m-2 y-1 및 14.13–138.00 t C 범위로 계산되었다. 조사된 4개 지역 중 탄소 저장량은 갈대(Phragmites australis)와 물이끼(Sphagnum palustre) 우점 지역에서 가장 높았으며, 탄소 격리율은 키버들(Salix koriyanagi)과 물이끼 우점 지역에서 가장 높았다. 탄소격리율은 1980년 전과 후에서 상당한 차이를 보였다(p < 0.01). 유기층의 깊이와 유기물 밀도는 4개 지점에서 유의한 차이를 보였고(p < 0.01), 인간의 교란이 있었던 질뫼늪에서 가장 낮은 값을 보였다. 습지에서 물이끼의 존재는 탄소 배출량을 줄임으로써 탄소 격리를 증가시키는 중요한 요소이지만, 인간의 교란은 탄소 격리율과 탄소 저장을 감소시키는 요인으로 작용한다. 따라서 습지 복원 평가를 위한 탄소 격리율과 탄소 저장량을 추정할 때 습지의 우점식물종과 인위적 교란의 존재를 고려해야 할 것이다. 둘째, 꿩고비의 최적 서식처를 찾기 위해 낮은 고도의 산지, 높은 고도의 산지, 그리고 산지습지의 식생 및 환경적 특성을 조사하였다. 꿩고비 개체군은 저고도 산지보다 고산지에서 더 잘 발달하였으나 높은 산악림의 낮은 조도는 이들의 번식 기회를 줄일 것으로 예상된다. 산지습지는 세 가지 서식지 유형 중 가장 높은 바이오매스를 기록했으며 번식에 대한 투자도 훨씬 더 높은 것으로 나타났다. 산지습지는 다른 서식지 유형에 비해 높은 광도, 기질 비옥도 및 수분 함량을 보였다. 따라서 한국의 세 서식지 유형 중 산지 습지가 꿩고비의 최적 서식지인 것으로 파악된다. 낮은 고도에서는 인간의 교란과 낮은 기질 수분 함량이 분포를 제한할 수 있는 요인일 것이며, 모든 지역에서 온도상승과 강수 빈도의 변화는 잠재적인 서식지 면적과 포자의 정착 기회를 감소시킬 수 있을 것이다. 이 연구는 꿩고비 개체군의 효과적인 보존을 위한 기질 수분 함량과 상대적인 광도의 중요성을 입증하고 습한 환경과 빛 가용성이 중요한 양치류의 생존을 위해 산지습지의 보존을 강조한다.Montane wetlands are ecosystems that have high biodiversity and carbon sequestration potential but are rapidly being damaged by climate change and human disturbance. The Odaesan National Park wetlands, designated as Ramsar wetlands, are representative montane wetlands in Korea. However, climate change and human disturbance are destroying montane wetlands by accelerating their dehydration. Wetland dehydration is known to cause carbon emissions and habitat fragmentation of wetland plants in montane wetlands. The purpose of this study was to evaluate the carbon sequestration potential of wetlands in Odaesan National Park, investigate the distribution of Osmundastrum cinnamomeum, a dominant plant in montane wetlands, and emphasize the conservation of montane wetlands. First, I estimated carbon sequestration rates and carbon storage in the montane wetlands of Odaesan National Park, Korea. I measured the depth of the organic layer at the three wetlands using a probe and collected 12 cores from four sites with different dominant plant species. The physicochemical characteristics of the cores were analyzed, and the 4 cores were dated with 210Pb using the constant rate of supply model. Based on physicochemical analyses and 210Pb dating, the carbon sequestration rate and carbon storage were calculated, ranging from 58.29 to 125.31 g C m−2 y−1 and 14.13–138.00 t C, respectively. Among the four sites studied, the carbon storage was highest at the Phragmites australis and Sphagnum palustre dominant site and the carbon sequestration rate was highest at the Salix koriyanagi and Sphagnum palustre dominant site. The carbon sequestration rate was substantially different before and after 1980 in montane wetlands in Korea (p < 0.01). The depth of the organic layer and the organic matter density were significantly different among the four sites (p < 0.01), with Jilmoe–neup showing the lowest value with recorded disturbance. I recommend that the dominant plant species and presence of disturbance be considered when estimating carbon sequestration rates and carbon storage for assessment of wetland restoration. The presence of S. palustre is an important factor in increasing carbon sequestration by diminishing carbon emissions. Disturbance is a factor that reduces the carbon sequestration rate and carbon storage, highlighting the importance of wetland conservation. Further studies are needed on the factors controlling carbon sequestration. Secondly, I investigated the vegetation and environmental factors in low- and high-altitude mountain ranges and montane wetlands to determine the optimal habitat for O. cinnamomeum. The populations of O. cinnamomeum developed better in high-altitude mountains than in low-altitude mountains. The low light intensity in high mountain forests reduces breeding opportunities. The montane wetlands recorded the highest biomass among the three habitat types, and the investment in reproduction was also significantly higher. The montane wetlands also showed higher light intensity, substrate fertility, and water content. Among these three habitats, montane wetlands were found to be the optimal habitat for O. cinnamomeum. At lower altitudes, human disturbance and low substrate water content are factors that may limit their distribution, and increased temperature and decreased precipitation frequency might reduce their potential habitat and settlement opportunities. When determining the optimal habitat for ferns, it is important to consider geography as well as altitude. this study demonstrates the importance of substrate water content and relative light intensity for the effective conservation of O. cinnamomeum populations, and emphasizes the conservation of montane wetlands for the survival of ferns, where wet environments and light availability are important.Chapter 1. Introduction 1 Chapter 2. Carbon Sequestration Potential in Montane wetlands of Korea 4 2.1.Introduction 4 2.2. Materials and Methods 6 2.2.1. Site description 6 2.2.2. Measurement of the organic layer depth 8 2.2.3. Sampling of the organic layer 9 2.2.4. Physicochemical properties and core dating 11 2.2.5. Determination of carbon storage and sequestration rate 12 2.2.6. Statistical analysis 13 2.3. Results 13 2.3.1. Bathymetry of the three wetlands 13 2.3.2. Physicochemical properties of the organic layer 14 2.3.3. Carbon content profile of the organic layer 17 2.3.4. Sedimentation and mass accumulation rate 19 2.3.5. Carbon storage and sequestration rate 19 2.4. Discussion 21 2.4.1. Dominant species affects carbon sequestration rate 21 2.4.2. Effect of organic layer depth on carbon storage 23 2.4.3. Effect of organic layer depth on carbon storage 25 2.5. Conclusion 29 Chapter 3. Characterization of Environmental Factors for the Conservation of Osmundastrum cinnamomeum 30 3.1.Introduction 30 3.2.Materials and Methods 33 3.2.1. Study sites 33 3.2.2. Field data collection 36 3.2.3. Analysis of substrate properties 38 3.2.4. Growth measurement 39 3.2.5. Statistical analysis 40 3.3 Results 41 3.3.1. Habitat types according to environmental variables and species composition 41 3.3.2. Environmental properties of the habitat types 46 3.3.3. Comparison of community structure among habitat types 49 3.4. Discussion 54 3.4.1. Comparison of environmental and community characteristics of three habitat types 54 3.4.2. Determination factor of optimal habitat for the O. cinnamomeum 57 3.4.3. Prospects for competitiveness of O. cinnamomeum in montane wetlands 59 3.5. Conclusion 63 References 64 국문 초록 83 Appendix A. 210Pb activity and depth profiles for core sampled in Odaesan National Park 86 Appendix B. Species and environmental factors according to habitat type of Osmundastrum cinnamomeum 87석