Time for dithering: fast and quantized random embeddings via the restricted isometry property

Recently, many works have focused on the characterization of non-linear dimensionality reduction methods obtained by quantizing linear embeddings, e.g., to reach fast processing time, efficient data compression procedures, novel geometry-preserving embeddings or to estimate the information/bits stored in this reduced data representation. In this work, we prove that many linear maps known to respect the restricted isometry property (RIP) can induce a quantized random embedding with controllable multiplicative and additive distortions with respect to the pairwise distances of the data points beings considered. In other words, linear matrices having fast matrix-vector multiplication algorithms (e.g., based on partial Fourier ensembles or on the adjacency matrix of unbalanced expanders) can be readily used in the definition of fast quantized embeddings with small distortions. This implication is made possible by applying right after the linear map an additive and random "dither" that stabilizes the impact of the uniform scalar quantization operator applied afterwards. For different categories of RIP matrices, i.e., for different linear embeddings of a metric space $(\mathcal K \subset \mathbb R^n, \ell_q)$ in $(\mathbb R^m, \ell_p)$ with $p,q \geq 1$, we derive upper bounds on the additive distortion induced by quantization, showing that it decays either when the embedding dimension $m$ increases or when the distance of a pair of embedded vectors in $\mathcal K$ decreases. Finally, we develop a novel "bi-dithered" quantization scheme, which allows for a reduced distortion that decreases when the embedding dimension grows and independently of the considered pair of vectors.Comment: Keywords: random projections, non-linear embeddings, quantization, dither, restricted isometry property, dimensionality reduction, compressive sensing, low-complexity signal models, fast and structured sensing matrices, quantized rank-one projections (31 pages

HUMAN CAPITAL AND FAMILY FARM IN THE OLIVE GROWING SYSTEM OF THE CALABRIA REGION

This research aims at pointing out those constrains and incentives conditioning family farm choices about investments, technical and managerial knowledge and expertness. The planned target has to be achieved through the attainment of three stages. Family farm involves a lot of people by different kind of employee relations, based mostly on a temporary work, that are often within the limits of the work rules. The organization solutions adopted by family farm produce several effects: among which investments and human capital allotment stand out. This research analyses family farm characteristics in a local rural system of the Calabria Region, as the result of the various European Community and domestic interventions and the specific physical, social and economic features in the considered territory; the attention is focused on the olive growing family farm. The survey is made through interviews carried out by qualified operators using questionnaires organized on different modules.Human capital, Family farm, Agricultural labour, Agribusiness, Labor and Human Capital,

A Socioeconomic Survey for the Recovery and Exploitation of the Terraced Vineyards of the Costa Viola (Calabria, Italy)

The new model of rural development, based on the recognition of the economic, social and environmental function of the European agriculture, mainly headed to make strategies of intervention concerning about, from one side, the competitive ability of the agricultural and agro-industrial enterprises, and, from the other, the increasing of the economic, human, environmental and historical-cultural resources. In such context the multi-functional role of agriculture becomes central and the agricultural operators have to adapt themselves to items (the territories, the rural societies, the consumers, etc.) and to different prescriptions related to demands linked up with the productivity and/or the territory (defence of the ground, of the landscape, of the cultural traditions, of the rural development, of the environment, of the quality). The present research documents the results of a territorial social-economic investigation, developed with the aim of examining the productive and environmental potentialities of the terraced winegrowing present in the territory of the "Costa Viola" in the province of Reggio Calabria (Calabria, Italy). The study starts from an analysis of the territory and individualizes a sample of wine-growing farms in order to examine, through specific social economic investigations (developed through a questionnaire), the actual conditions of the grape cultivated terraces, the status of the "representative farmer" of the vineyards and the achieved economic results. The collected data concerned some social characteristics (age, degree of education, availability and/or propensity to innovation, to introduce new technologies, etc.).agro-environmental measures, multi-functionality, landscape safeguard, Agribusiness, Q32, Q56, R51,

Nitrous oxide emissions in corn (Zea mays L) as affected by timing, method of application and source of dairy manure.

Thesis Doctor of Philosophy in Environmental Sciences in University of Guelph, Ontario, Canada. 2016Field trials were conducted during three years to evaluate the effect of timing, method of application and manure source on N2O emissions and corn grain yield at Elora, ON, Canada. A randomized block design was set up every year, evaluating two timings (fall vs. spring), three methods of manure application (surface broadcasting, incorporation and injection) and two manure sources (raw, RM vs. anaerobically digested, AD), using non steady state chambers. Three and two years of data were used to evaluate the effect of manure application timing and manure source respectively on N2O emission, considering also application methods in each experiment. A hybrid, decision tree-based flux calculation method (DTBM) was developed and chosen to calculate N2O emissions, given that it advantaged to other methods due to its ability to match each data type with the best model. Nitrous oxide emissions did not respond to timing of manure application; however, as the interaction year by manure application timing as well as application method significantly affected N2O emissions (p< 0.01 and p< 0.05, respectively). The effect of method on cumulative N2O emissions depended on manure source(p<0.01), since surface broadcast AD had the highest emission (6.4 kg N2O-N ha-1), and both injected AD and incorporated RM had the lowest values (2.6 kg and 2.8 N2O-N ha-1 , respectively). Manure source tended to affect cumulative N2O emissions (F=4.67, p<0.1), with the largest emissions for AD (4.8 kg N2O-N ha-1). Anaerobically digested manure was proven to reduce cumulative N2O emissions when it was fall injected to corn in cold climates; however, if AD is broadcasted or broadcasted and incorporated, it may result in greater N2O emissions than those produced by RM. Short (2-3 yrs.) and long term (26 yrs.) trends for cumulative N2O emissions were simulated with a process based model (DNDC-CAN). Even though no difference between predicted application timings was found at short term, spring application was detected to decrease N2O emissions in the long term. The inter-annual variability canceled the effects of method of application in the long term on predicted N2O emissions. Injection of AD showed to be a goodtechnique to mitigate predicted N2O emissions in the long term.EEA BalcarceFil: Cambareri, Gustavo Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Claudia Wagner-Riddle. University of Guelph; Canad

Low-complexity Multiclass Encryption by Compressed Sensing

The idea that compressed sensing may be used to encrypt information from unauthorised receivers has already been envisioned, but never explored in depth since its security may seem compromised by the linearity of its encoding process. In this paper we apply this simple encoding to define a general private-key encryption scheme in which a transmitter distributes the same encoded measurements to receivers of different classes, which are provided partially corrupted encoding matrices and are thus allowed to decode the acquired signal at provably different levels of recovery quality. The security properties of this scheme are thoroughly analysed: firstly, the properties of our multiclass encryption are theoretically investigated by deriving performance bounds on the recovery quality attained by lower-class receivers with respect to high-class ones. Then we perform a statistical analysis of the measurements to show that, although not perfectly secure, compressed sensing grants some level of security that comes at almost-zero cost and thus may benefit resource-limited applications. In addition to this we report some exemplary applications of multiclass encryption by compressed sensing of speech signals, electrocardiographic tracks and images, in which quality degradation is quantified as the impossibility of some feature extraction algorithms to obtain sensitive information from suitably degraded signal recoveries.Comment: IEEE Transactions on Signal Processing, accepted for publication. Article in pres

Action Research as Professional Development: Creating Effective Professional Development in Every Classroom

Professional development is a critical component of teacher professional growth that directly influences increased student learning and achievement. As professionals, teachers continue to develop their knowledge and skills with the aim of improving their teaching to assure that students can learn better. A huge investment in time and resources is invested in teacher professional learning every year. However, teachers report, and research supports, that teacher professional development often does not meet teachers’ needs and does not perform its integral function of creating a sustained change in teacher behavior that leads to a corresponding positive change in student achievement. This problem of practice directly affects the success of all students, teachers, and schools. There exists, however, forms of professional development that do lead to this type of positive change, and one of those professional development models is classroombased action research. This dissertation reports outcomes of a mixed-methods actionresearch study exploring the effect of training teachers to use classroom-based action research as professional development in which they identified and worked through the action research cycle to solve their own problems of practice. It details a study of teachers who embarked upon cycles of action research in their own classrooms and teaching environments. Quantitative and qualitative data analyses indicate positive changes occurred in teacher behavior through their conducting action research projects and that positive changes occurred in learning and achievement among their students. Further analysis of study data revealed increased understanding of the purpose of professional development, need for sustained change, and expectations of professional development that contains the characteristics that support the development of those changes. While a body of research on classroom-based action research already exists, findings from this study supports and extends understanding of the characteristics of effective professional development and establishes classroom-based action research as one of those practices. Additionally, this study’s finding of action research as a form of professional development that gives teachers “permission” to prioritize what they value in their classrooms opens up an additional interesting view into how teachers’ professional time is compromised by outside forces and requirements, which is an area that merits further investigation

On Known-Plaintext Attacks to a Compressed Sensing-based Encryption: A Quantitative Analysis

Despite the linearity of its encoding, compressed sensing may be used to provide a limited form of data protection when random encoding matrices are used to produce sets of low-dimensional measurements (ciphertexts). In this paper we quantify by theoretical means the resistance of the least complex form of this kind of encoding against known-plaintext attacks. For both standard compressed sensing with antipodal random matrices and recent multiclass encryption schemes based on it, we show how the number of candidate encoding matrices that match a typical plaintext-ciphertext pair is so large that the search for the true encoding matrix inconclusive. Such results on the practical ineffectiveness of known-plaintext attacks underlie the fact that even closely-related signal recovery under encoding matrix uncertainty is doomed to fail. Practical attacks are then exemplified by applying compressed sensing with antipodal random matrices as a multiclass encryption scheme to signals such as images and electrocardiographic tracks, showing that the extracted information on the true encoding matrix from a plaintext-ciphertext pair leads to no significant signal recovery quality increase. This theoretical and empirical evidence clarifies that, although not perfectly secure, both standard compressed sensing and multiclass encryption schemes feature a noteworthy level of security against known-plaintext attacks, therefore increasing its appeal as a negligible-cost encryption method for resource-limited sensing applications.Comment: IEEE Transactions on Information Forensics and Security, accepted for publication. Article in pres

Consistent Basis Pursuit for Signal and Matrix Estimates in Quantized Compressed Sensing

This paper focuses on the estimation of low-complexity signals when they are observed through $M$ uniformly quantized compressive observations. Among such signals, we consider 1-D sparse vectors, low-rank matrices, or compressible signals that are well approximated by one of these two models. In this context, we prove the estimation efficiency of a variant of Basis Pursuit Denoise, called Consistent Basis Pursuit (CoBP), enforcing consistency between the observations and the re-observed estimate, while promoting its low-complexity nature. We show that the reconstruction error of CoBP decays like $M^{-1/4}$ when all parameters but $M$ are fixed. Our proof is connected to recent bounds on the proximity of vectors or matrices when (i) those belong to a set of small intrinsic "dimension", as measured by the Gaussian mean width, and (ii) they share the same quantized (dithered) random projections. By solving CoBP with a proximal algorithm, we provide some extensive numerical observations that confirm the theoretical bound as $M$ is increased, displaying even faster error decay than predicted. The same phenomenon is observed in the special, yet important case of 1-bit CS.Comment: Keywords: Quantized compressed sensing, quantization, consistency, error decay, low-rank, sparsity. 10 pages, 3 figures. Note abbout this version: title change, typo corrections, clarification of the context, adding a comparison with BPD

An ultra-fast method of DNA extraction from Neurospora

We have found that the DNA extraction procedure of Metzenberg and Baitch (Neurospora Newsl. 28:20)/Stevens and Metzenberg (Neurospora Newsl. 29:27) while giving excellent yield and size of DNA, is somewhat cumbersome and also results in the occasional sample that proves to be uncuttable

Caratterizzazione e generazione di segnali PWM per amplificatori in classe D ad alta efficienza

The convergence of information technology and consumer electronics towards battery powered portable devices has increased the interest in high efficiency, low dissipation amplifiers. Class D amplifiers are the state of the art in low power consumption and high performance amplification. In this thesis we explore the possibility of exploiting nonlinearities introduced by the PWM modulation, by designing an optimized modulation law which scales its carrier frequency adaptively with the input signal's average power while preserving the SNR, thus reducing power consumption. This is achieved by means of a novel analytical model of the PWM output spectrum, which shows how interfering harmonics and their bandwidth affect the spectrum. This allows for frequency scaling with negligible aliasing between the baseband spectrum and its harmonics. We performed low noise power spectrum measurements on PWM modulations generated by comparing variable bandwidth, random test signals with a variable frequency triangular wave carrier. The experimental results show that power-optimized frequency scaling is both feasible and effective. The new analytical model also suggests a new PWM architecture that can be applied to digitally encoded input signals which are predistorted and compared with a cosine carrier, which is accurately synthesized by a digital oscillator. This approach has been simulated in a realistic noisy model and tested in our measurement setup. A zero crossing search on the obtained PWM modulation law proves that this approach yields an equivalent signal quality with respect to traditional PWM schemes, while entailing the use of signals whose bandwidth is remarkably smaller due to the use of a cosine instead of a triangular carrier