Statistical Learning for Structured Models: Tree Based Methods and Neural Networks

In this thesis, estimation in regression and classification problems which include low dimensional structures are considered. The underlying question is the following. How well do statistical learn- ing methods perform for models with low dimensional structures? We approach this question using various algorithms in various settings. For our first main contribution, we prove optimal convergence rates in a classification setting using neural networks. While non-optimal rates ex- isted for this problem, we are the first to prove optimal ones. Secondly, we introduce a new tree based algorithm we named random planted forest. It adapts particularly well to models which consist of low dimensional structures. We examine its performance in simulation studies and include some theoretical backing by proving optimal convergence rates in certain settings for a modification of the algorithm. Additionally, a generalized version of the algorithm is included, which can be used in classification settings. In a further contribution, we prove optimal con- vergence rates for the local linear smooth backfitting algorithm. While such rates have already been established, we bring a new simpler perspective to the problem which leads to better understanding and easier interpretation. Additionally, given an estimator in a regression setting, we propose a constraint which leads to a unique decomposition. This decomposition is useful for visualising and interpreting the estimator, in particular if it consits of low dimenional structures

Bodyweight squats can induce post-activation performance enhancement on jumping performance:a brief report

Post-activation potentiation enhancement (PAPE) refers to increased force generation following a muscular conditioning pre-activity that acutely enhances subsequent strength and power performance. Athlete apprehension to use heavy weights (i.e. >80%1RM) immediately before a competition or inability to use weights before the performance (e.g. due to regulations) prevent materialising the benefits of PAPE. Therefore, this study examined whether PAPE can be induced with bodyweight squats. Sixteen healthy, team sports players (male: 10, female: 6, mean ± SD: age 22.2 ± 3.0 years, height 1.67 ± 0.08 m, body mass 70.2 ± 8.2 kg) performed three sets of ten repetitions of bodyweight squats with 30 seconds recovery between each set. A countermovement jump was performed 5 minutes before, 2 and 4 minutes after the squat sets and jump height was calculated. The results showed existence of PAPE with the jump height increasing at both 2 (30.8 ± 5.6 cm, p = 0.045, g = 0.21) and 4 (30.8 ± 6.1 cm, p = 0.037, g = 0.20) minutes, compared to baseline (29.5 ± 6.4 cm). This is the first study to use bodyweight squats rather than loaded squats. Our findings indicate that three sets of ten repetitions of squats using bodyweight only can be a sufficient stimulus to induce PAPE

Convergence opportunities and factors influencing the use of internet and telephony by rural women in South Africa and India towards empowerment

Abstract: Access to Information and Communication Technologies (ICTs) can have dramatic impact on poverty alleviation for rural women and for achieving socio economic development goals. Rural women need to treat ICTs as an empowerment tool and a means to a living. The use of mobile communication devices and internet are changing the way agricultural activities are managed by farmers nowadays. Rural women's lack of mobility and less hands-on computer experience might hinder women's welfare and empowerment. This paper analyses how use of the telephony (both cellular and land line), internet and other ICTs can benefit rural women in educational, business and economic sector. Women in rural India and rural South Africa were marginalized partly due to their lack of ability in being vocal when it comes to empowering themselves using ICTs due to cultural norms in India, and apartheid in South Africa. Over the years, unlike other developing countries, the above-mentioned countries have its unique ICT projects meant for empowering rural women. This paper is driven from the authors' commitment for rural development and rural women empowerment. It highlights different low-cost ICT initiatives and strategies taken by women's organizations, various companies and other non-governmental organizations (NGOs) for rural women empowerment. The paper also highlights various factors influencing use of internet and mobile phone adoption by rural women. Various bottlenecks for the community projects, factors de-motivating the use of mobile phones and internet by rural women and possible solutions for these are also mentioned

Information and communication technology policy imperatives for rural women empowerment : focus on South Africa

Abstract: It has been established that Information and Communication Technologies (ICTs) are key drivers for rural development. However, while many countries such as India and South Africa have made significant investments in rural ICT infrastructure and its developmental spin-offs, rural women are still neglected when it comes to access to ICTs. This neglect is evident in the ICT policy initiatives in South Africa as an example, where the relevant policies lack any significant or direct attention to rural women’s development. If ICT policies do not address the gendered digital divide in rural areas gender inequality will be encouraged. This paper gives insights on how information exchange by means of ICTs such as Internet, mobile phones and radio could foster economic growth and empowerment of rural women in South Africa. In addition, the paper discusses the role of relevant stakeholders in ICT policy formulation for more effective and appropriate communication, and innovative ways of using ICTs for women empowerment in rural areas. The authors make recommendations for ICT policy development that would better serve the needs of rural women leading to their empowerment

Design and Implementation of Intrusion Detection Systems using RPL and AOVD Protocols-based Wireless Sensor Networks

Wireless Sensor Network (WSN) technology has grown in importance in recent years. All WSN implementations need secure data transmission between sensor nodes and base stations. Sensor node attacks introduce new threats to the WSN. As a result, an appropriate Intrusion Detection System (IDS) is required in WSN for defending against security attacks and detecting attacks on sensor nodes. In this study, we use the Routing Protocol for Low Power and Lossy Networks (RPL) for addressing security services in WSN by identifying IDS with a network size of more or less 20 nodes and introducing 10% malicious nodes. The method described above is used on Cooja in the VMware virtual machine Workstation with the InstantContiki2.7 operating system. To track the movement of nodes, find network attacks, and spot dropped packets during IDS in WSN, an algorithm is implemented in the Network Simulator (NS2) using the Ad-hoc On-Demand Distance Vector (AODV) protocol in the Linux operating system.Keywords—Intrusion Detection Systems, wireless sensor networks, Cooja simulator, sensor nodes, NS

Convective Depletion During The Fast Propagation Of A Nanosphere Through A Polymer Solution

A theory of nonlinear convective depletion is set up as a nanosphere translates fast through a semidilute polymer solution. For nanospheres a self-consistent field theory in the Rouse approximation is often legitimate. A self-similar solution of the convective depletion equation is argued to be feasible at high velocities. The nature of the thin boundary layer in front of the propagating particle is analyzed. One example of convective depletion is when a charged protein moves through a semidilute polymer under the influence of a high electric field. The protein velocity is then proportional to the fifth power of the field. The theory could be useful in interpreting the separation of protein mixtures by microchip electrophoresis.Comment: 12 pages, 2 figure

Convergence Opportunities and Factors Influencing the Use of Internet and Telephony by the Rural Women in South Africa and India towards Empowerment.

Abstract. Access to Information and Communication Technologies (ICTs) can have dramatic impact on poverty alleviation for rural women and for achieving socio economic development goals. Rural women need to treat ICTs as an empowerment tool and a means to a living. The use of mobile communication devices and internet are changing the way agricultural activities are managed by farmers nowadays. Rural women's lack of mobility and less hands-on computer experience might hinder women's welfare and empowerment. This paper analyses how use of the telephony (both cellular and land line), internet and other ICTs can benefit rural women in educational, business and economic sector. Women in rural India and rural South Africa were marginalized partly due to their lack of ability in being vocal when it comes to empowering themselves using ICTs due to cultural norms in India, and apartheid in South Africa. Over the years, unlike other developing countries, the above-mentioned countries have its unique ICT projects meant for empowering rural women. This paper is driven from the authors' commitment for rural development and rural women empowerment. It highlights different low-cost ICT initiatives and strategies taken by women's organizations, various companies and other non-governmental organizations (NGOs) for rural women empowerment. The paper also highlights various factors influencing use of internet and mobile phone adoption by rural women. Various bottlenecks for the community projects, factors de-motivating the use of mobile phones and internet by rural women and possible solutions for these are also mentioned

Evaluation of Veterinary-Specific Interpretive Criteria for Susceptibility Testing of Streptococcus equi Subspecies with Trimethoprim-Sulfamethoxazole and Trimethoprim-Sulfadiazine

Antimicrobial susceptibility test results for trimethoprim-sulfadiazine with Streptococcus equi subspecies are interpreted based on human data for trimethoprim-sulfamethoxazole. The veterinary-specific data generated in this study support a single breakpoint for testing trimethoprim-sulfamethoxazole and/or trimethoprim-sulfadiazine with S. equi. This study indicates trimethoprim-sulfamethoxazole as an acceptable surrogate for trimethoprim-sulfadiazine with S. equi

Fast quasi-centroid molecular dynamics for water and ice

We describe how the fast quasi-centroid molecular dynamics (f-QCMD) method can be applied to condensed phase systems by approximating the quasi-centroid potential of mean force as a sum of inter- and intra-molecular corrections to the classical interaction potential. The corrections are found by using a regularised iterative Boltzmann inversion procedure to recover the inter- and intra-molecular quasi-centroid distribution functions obtained from a path integral molecular dynamics simulation. The resulting methodology is found to give good agreement with a previously published QCMD dipole absorption spectrum for liquid water, and satisfactory agreement for ice. It also gives good agreement with spectra from a recent implementation of CMD that uses a pre-computed elevated temperature potential of mean force. Modern centroid molecular dynamics methods therefore appear to be reaching a consensus regarding the impact of nuclear quantum effects on the vibrational spectra of water and ice.Comment: 10 pages, 4 figures, plus supplementary information and toc figur