Feb
29
Predictive Equations to Assess the Effect of Lactic Acid and Temperature on Bacterial Growth in a Model Meat System
February 29, 2008 | Comments Off
Meat microflora is mainly composed of Acinetobacter, Moraxella, Brochothrix termosphacta, Lactobacillus, Pseudomonas and Enterobacteriaceae family genera, such as Klebsiella sp. and E. coli. In natural conditions meat pH can range from about 6.0 (being close to the optimum level for most pathogenic and alteration-causing
bacteria) to values close to 5.5, at which microbial growth rate decreases significantly. Combining low pH with other factors
such as low temperatures can almost completely prevent microbial growth from occurring. Muscle pH variation is highly dependent
on the tissue glycogen level at the time of slaughter.
bacteria) to values close to 5.5, at which microbial growth rate decreases significantly. Combining low pH with other factors
such as low temperatures can almost completely prevent microbial growth from occurring. Muscle pH variation is highly dependent
on the tissue glycogen level at the time of slaughter.
Weak organic acids tend to be more effective as antimicrobials than strong acids because they acidify the interior of the
cell (Anderson et al., 1987). Antimicrobial activities exerted by organic acids depend upon i) pH reduction, ii) minimizing
dissociation of the acid and iii) maximizing toxicity of the acid molecule (Anderson et al., 1987). Lactic acid produces an
inhibitory effect because of the decrease in pH; this acid could act both on the meat muscle flora itself and on that of the
fat, although such antimicrobial effect varies, not only according to the type of acid used, but also according to the microbial
variety to be treated. Sometimes it could be bacteriostatic and sometimes it could have a bactericidal action. High efficiency
in meat surface sanitization due to lactic acid addition has been widely reported (Nakai and Siebert, 2004).
cell (Anderson et al., 1987). Antimicrobial activities exerted by organic acids depend upon i) pH reduction, ii) minimizing
dissociation of the acid and iii) maximizing toxicity of the acid molecule (Anderson et al., 1987). Lactic acid produces an
inhibitory effect because of the decrease in pH; this acid could act both on the meat muscle flora itself and on that of the
fat, although such antimicrobial effect varies, not only according to the type of acid used, but also according to the microbial
variety to be treated. Sometimes it could be bacteriostatic and sometimes it could have a bactericidal action. High efficiency
in meat surface sanitization due to lactic acid addition has been widely reported (Nakai and Siebert, 2004).
The objective of this work is to analyze and mathematically model the effect of storage temperatures (0°C, 4°C and 10°C) on
the growth of three microorganisms isolated from beef samples: Klebsiella sp., E. coli and Pseudomonas sp., inoculated in a culture broth with different concentrations of lactic acid leading to pH values ranging between 5.6 and
6.1.
the growth of three microorganisms isolated from beef samples: Klebsiella sp., E. coli and Pseudomonas sp., inoculated in a culture broth with different concentrations of lactic acid leading to pH values ranging between 5.6 and
6.1.
- Content Type Book Chapter
- DOI 10.1007/978-0-387-75430-7_24
- Authors
- F. Coll Cárdenas, Universidad Nacional Centro de Investigación y Desarrollo en Criotecnología de Alimentos La Plata Argentina
- L. Giannuzzi, Universidad Nacional Centro de Investigación y Desarrollo en Criotecnología de Alimentos La Plata Argentina
- N. E. Zaritzky, Universidad Nacional Centro de Investigación y Desarrollo en Criotecnología de Alimentos La Plata Argentina
- Book Series Food Engineering series
- Print ISSN 1571-0297
- Book Food Engineering: Integrated Approaches
- DOI 10.1007/978-0-387-75430-7
- Online ISBN 978-0-387-75430-7
- Print ISBN 978-0-387-75429-1
Feb
28
An adaptive personalized news dissemination system
February 28, 2008 | Comments Off
Abstract With the explosive growth of the Word Wide Web, information overload became a crucial concern. In a data-rich information-poor
environment like the Web, the discrimination of useful or desirable information out of tons of mostly worthless data became
a tedious task. The role of Machine Learning in tackling this problem is thoroughly discussed in the literature, but few systems
are available for public use. In this work, we bridge theory to practice, by implementing a web-based news reader enhanced
with a specifically designed machine learning framework for dynamic content personalization. This way, we get the chance to
examine applicability and implementation issues and discuss the effectiveness of machine learning methods for the classification
of real-world text streams. The main features of our system named PersoNews are: (a) the aggregation of many different news
sources that offer an RSS version of their content, (b) incremental filtering, offering dynamic personalization of the content
not only per user but also per each feed a user is subscribed to, and (c) the ability for every user to watch a more abstracted
topic of interest by filtering through a taxonomy of topics. PersoNews is freely available for public use on the WWW (http://news.csd.auth.gr).
environment like the Web, the discrimination of useful or desirable information out of tons of mostly worthless data became
a tedious task. The role of Machine Learning in tackling this problem is thoroughly discussed in the literature, but few systems
are available for public use. In this work, we bridge theory to practice, by implementing a web-based news reader enhanced
with a specifically designed machine learning framework for dynamic content personalization. This way, we get the chance to
examine applicability and implementation issues and discuss the effectiveness of machine learning methods for the classification
of real-world text streams. The main features of our system named PersoNews are: (a) the aggregation of many different news
sources that offer an RSS version of their content, (b) incremental filtering, offering dynamic personalization of the content
not only per user but also per each feed a user is subscribed to, and (c) the ability for every user to watch a more abstracted
topic of interest by filtering through a taxonomy of topics. PersoNews is freely available for public use on the WWW (http://news.csd.auth.gr).
- Content Type Journal Article
- DOI 10.1007/s10844-008-0053-8
- Authors
- Ioannis Katakis, Aristotle University Department of Informatics 54124 Thessaloniki Greece
- Grigorios Tsoumakas, Aristotle University Department of Informatics 54124 Thessaloniki Greece
- Evangelos Banos, Aristotle University Department of Informatics 54124 Thessaloniki Greece
- Nick Bassiliades, Aristotle University Department of Informatics 54124 Thessaloniki Greece
- Ioannis Vlahavas, Aristotle University Department of Informatics 54124 Thessaloniki Greece
- Journal Journal of Intelligent Information Systems
- Online ISSN 1573-7675
- Print ISSN 0925-9902
Feb
28
Monte Carlo Integration for Quasi–linear Models
February 28, 2008 | Comments Off
In this contribution we consider the inversion of quasi-linear models by means of Monte-Carlo methods. Quasi-linear models
are a special class of non-linear models, which can be formally written in matrix-vector formulation but whose design matrix
depends on a subset of the unknown parameters. A large class of geodetic problems can be recast as quasi-linear models. As
there exist no general analytical solutions for the quasi-linear model, Monte Carlo optimization techniques in the context
of a Bayesian approach are investigated here. In order to accelerate the Monte Carlo method we utilize the analytical solution
of the linear model under the condition that the unknown parameters in the design matrix are considered as constant. Thereby
the sampling dimension in the Monte Carlo approach can be reduced. The estimators for expectation and covariance of the parameters
that we derive turn out as weighted means of the individual sample least-squares solutions. We develop an efficient set of
algorithms for the solution of quasi-linear models using Monte Carlo techniques and demonstrate the efficiency of the method
in a numerical example which is taken from satellite geodesy and gravity field recovery. Two groups of unknown parameters
are relevant in this example: the spherical harmonic coefficients of a gravity field model, and the state vectors of the satellite(s)
which affect the observation model through the design matrix.
are a special class of non-linear models, which can be formally written in matrix-vector formulation but whose design matrix
depends on a subset of the unknown parameters. A large class of geodetic problems can be recast as quasi-linear models. As
there exist no general analytical solutions for the quasi-linear model, Monte Carlo optimization techniques in the context
of a Bayesian approach are investigated here. In order to accelerate the Monte Carlo method we utilize the analytical solution
of the linear model under the condition that the unknown parameters in the design matrix are considered as constant. Thereby
the sampling dimension in the Monte Carlo approach can be reduced. The estimators for expectation and covariance of the parameters
that we derive turn out as weighted means of the individual sample least-squares solutions. We develop an efficient set of
algorithms for the solution of quasi-linear models using Monte Carlo techniques and demonstrate the efficiency of the method
in a numerical example which is taken from satellite geodesy and gravity field recovery. Two groups of unknown parameters
are relevant in this example: the spherical harmonic coefficients of a gravity field model, and the state vectors of the satellite(s)
which affect the observation model through the design matrix.
- Content Type Book Chapter
- DOI 10.1007/978-3-540-74584-6_55
- Authors
- B. Gundlich, Forschungszentrum Jülich GmbH Central Institute for Electronics 52425 Jülich Germany
- J. Kusche, Delft Institute of Earth Observation and Space System (DEOS) Kluyverweg 1 PO box 5058 TU Delft 2600 GB Delft The Netherlands
- Book Series International Association of Geodesy Symposia
- Print ISSN 0939-9585
- Book Series Volume Volume 132
- Book VI Hotine-Marussi Symposium on Theoretical and Computational Geodesy
- DOI 10.1007/978-3-540-74584-6
- Online ISBN 978-3-540-74584-6
- Print ISBN 978-3-540-74583-9
- Book Part Part IV
Feb
27
Alambic : a privacy-preserving recommender system for electronic commerce
February 27, 2008 | Comments Off
Abstract Recommender systems enable merchants to assist customers in finding products that best satisfy their needs. Unfortunately,
current recommender systems suffer from various privacy-protection vulnerabilities. Customers should be able to keep private
their personal information, including their buying preferences, and they should not be tracked against their will. The commercial
interests of merchants should also be protected by allowing them to make accurate recommendations without revealing legitimately
compiled valuable information to third parties. We introduce a theoretical approach for a system called Alambic, which achieves
the above privacy-protection objectives in a hybrid recommender system that combines content-based, demographic and collaborative
filtering techniques. Our system splits customer data between the merchant and a semi-trusted third party, so that neither
can derive sensitive information from their share alone. Therefore, the system could only be subverted by a coalition between
these two parties.
current recommender systems suffer from various privacy-protection vulnerabilities. Customers should be able to keep private
their personal information, including their buying preferences, and they should not be tracked against their will. The commercial
interests of merchants should also be protected by allowing them to make accurate recommendations without revealing legitimately
compiled valuable information to third parties. We introduce a theoretical approach for a system called Alambic, which achieves
the above privacy-protection objectives in a hybrid recommender system that combines content-based, demographic and collaborative
filtering techniques. Our system splits customer data between the merchant and a semi-trusted third party, so that neither
can derive sensitive information from their share alone. Therefore, the system could only be subverted by a coalition between
these two parties.
- Content Type Journal Article
- Category Regular Contribution
- DOI 10.1007/s10207-007-0049-3
- Authors
- Esma Aïmeur, Université de Montréal Département d’informatique et de recherche opérationnelle Montréal Canada
- Gilles Brassard, Université de Montréal Département d’informatique et de recherche opérationnelle Montréal Canada
- José M. Fernandez, École Polytechnique de Montréal Département de génie informatique Montréal Canada
- Flavien Serge Mani Onana, Université de Montréal Département d’informatique et de recherche opérationnelle Montréal Canada
- Journal International Journal of Information Security
- Online ISSN 1615-5270
- Print ISSN 1615-5262
Feb
27
Variable selection in multivariate methods using global score estimation
February 27, 2008 | Comments Off
Abstract A variable selection method using global score estimation is proposed, which is applicable as a selection criterion in any
multivariate method without external variables such as principal component analysis, factor analysis and correspondence analysis.
This method selects a subset of variables by which we approximate the original global scores as much as possible in the context
of least squares, where the global scores, e.g. principal component scores, factor scores and individual scores, are computed
based on the selected variables. Global scores are usually orthogonal. Therefore, the estimated global scores should be restricted
to being mutually orthogonal. According to how to satisfy that restriction, we propose three computational steps to estimate
the scores. Example data is analyzed to demonstrate the performance and usefulness of the proposed method, in which the proposed
algorithm is evaluated and the results obtained using four cost-saving selection procedures are compared. This example shows
that combining these steps and procedures yields more accurate results quickly.
multivariate method without external variables such as principal component analysis, factor analysis and correspondence analysis.
This method selects a subset of variables by which we approximate the original global scores as much as possible in the context
of least squares, where the global scores, e.g. principal component scores, factor scores and individual scores, are computed
based on the selected variables. Global scores are usually orthogonal. Therefore, the estimated global scores should be restricted
to being mutually orthogonal. According to how to satisfy that restriction, we propose three computational steps to estimate
the scores. Example data is analyzed to demonstrate the performance and usefulness of the proposed method, in which the proposed
algorithm is evaluated and the results obtained using four cost-saving selection procedures are compared. This example shows
that combining these steps and procedures yields more accurate results quickly.
- Content Type Journal Article
- Category Original Paper
- DOI 10.1007/s00180-008-0109-9
- Authors
- Kaoru Fueda, Okayama University Graduate School of Environmental Science Naka 3-1-1, Tsushima Okayama 700-8530 Japan
- Masaya Iizuka, Okayama University Graduate School of Environmental Science Naka 3-1-1, Tsushima Okayama 700-8530 Japan
- Yuichi Mori, Okayama University of Science Department of Socio-Information 1-1, Ridai-cho Okayama 700-005 Japan
- Journal Computational Statistics
- Online ISSN 1613-9658
- Print ISSN 0943-4062
Feb
27
Efficient Resource Allocation and Paving the Way Towards Highly Efficient IMT-Advanced Systems
February 27, 2008 | Comments Off
Abstract Recently, new network topologies including relays and meshed networks have emerged as a key technology receiving a lot of
attention due to the increasing need for additional resources such as spectrum, and required high data-rates specified by
the International Mobile Telecommunication-Advanced (IMT-Advanced) systems (Report ITU-R M.1645, Framework and overall objectives
of the future development of IMT-2000 and systems beyond IMT-2000). These systems are designed to provide diverse services
sustaining low to high mobility applications and yielding a significant improvement in terms of Quality-of-Service (QoS).
In this paper, we identify and describe the novel network topologies that will be able to accommodate the high data rates
demanded within the spectrum scarcity paradigm. By efficiently integrating mesh networks and flexible resource sharing, the
overall network efficiency is shown to increase. In addition, direct terminal-to-terminal (T2T) communication both with and
without the use of relays is presented, where terminals communicate without the use of base stations (BSs) as it is done in
conventional systems. The results show significant gains in terms of throughput, average frame delays and power consumption
compared to conventional networks. Finally, open issues and potential challenges are addressed.
attention due to the increasing need for additional resources such as spectrum, and required high data-rates specified by
the International Mobile Telecommunication-Advanced (IMT-Advanced) systems (Report ITU-R M.1645, Framework and overall objectives
of the future development of IMT-2000 and systems beyond IMT-2000). These systems are designed to provide diverse services
sustaining low to high mobility applications and yielding a significant improvement in terms of Quality-of-Service (QoS).
In this paper, we identify and describe the novel network topologies that will be able to accommodate the high data rates
demanded within the spectrum scarcity paradigm. By efficiently integrating mesh networks and flexible resource sharing, the
overall network efficiency is shown to increase. In addition, direct terminal-to-terminal (T2T) communication both with and
without the use of relays is presented, where terminals communicate without the use of base stations (BSs) as it is done in
conventional systems. The results show significant gains in terms of throughput, average frame delays and power consumption
compared to conventional networks. Finally, open issues and potential challenges are addressed.
- Content Type Journal Article
- DOI 10.1007/s11277-008-9483-4
- Authors
- Mehdi Bennis, University of Oulu Centre for Wireless Communications (CWC) Oulu Finland
- Gareth Middleton, Rice University Centre for Multimedia and Communications (CMC) Houston USA
- Jorma Lilleberg, Nokia Oulu Finland
- Journal Wireless Personal Communications
- Online ISSN 1572-834X
- Print ISSN 0929-6212
Feb
27
Lumbricid associations on a former open clay pit after recultivation with different tree species
February 27, 2008 | Comments Off
Abstract The earthworm fauna was recorded from a former open clay pit five and seven years after the area had been recultivated with
various tree species. The highest abundances (200–245 specimens/m2) and biomasses (46.8 to 48.4 g/m2) were found in the following stand types: mixed woodland of balsam poplar (various sorts) and grey alder (Alnus incana (L.)Moench), mixed woodland of balsam poplar (Andoscoggin) and black alder (Alnus glutinosa (L.)Gaertn.), and a pure stand of black alder. Clearly lower values were found in a plot with common oaks (Quercus robur L.) under a dense shelterwood of naturally regenerated willows (Salix spec.), and a plot exclusively stocked with naturally regenerated willows. The rapid resettlement of the backfilled, compacted
clay soil is above all explained by the high pH-values found in the surface soil. The differences between the studied plots
regarding total abundance and biomass might be explained by the different qualities and amounts of litter. The highest species
diversity — expressed by the Shannon-index — and the highest proportion of endogeic species, particularlyAporrectodea caliginosa Savigny 1826, were calculated for the two stands with a mixture of alder and balsam poplar. This result could have been caused
by the lack of parent soil bed and the particularly high pH-value of the soils found there.
various tree species. The highest abundances (200–245 specimens/m2) and biomasses (46.8 to 48.4 g/m2) were found in the following stand types: mixed woodland of balsam poplar (various sorts) and grey alder (Alnus incana (L.)Moench), mixed woodland of balsam poplar (Andoscoggin) and black alder (Alnus glutinosa (L.)Gaertn.), and a pure stand of black alder. Clearly lower values were found in a plot with common oaks (Quercus robur L.) under a dense shelterwood of naturally regenerated willows (Salix spec.), and a plot exclusively stocked with naturally regenerated willows. The rapid resettlement of the backfilled, compacted
clay soil is above all explained by the high pH-values found in the surface soil. The differences between the studied plots
regarding total abundance and biomass might be explained by the different qualities and amounts of litter. The highest species
diversity — expressed by the Shannon-index — and the highest proportion of endogeic species, particularlyAporrectodea caliginosa Savigny 1826, were calculated for the two stands with a mixture of alder and balsam poplar. This result could have been caused
by the lack of parent soil bed and the particularly high pH-value of the soils found there.
- Content Type Journal Article
- DOI 10.1007/BF02832969
- Authors
- Sabine Ammer, Sonnenstraße 1 84079 Attenhausen Germany
- Christian Ammer, Lehrstuhl für Waldbau und Forsteinrichtung der Ludwig-Maximilians-Universität München Am Hochanger 13 85354 Freising Germany
- Journal European Journal of Forest Research
- Online ISSN 1612-4677
- Print ISSN 1612-4669
- Journal Volume Volume 117
- Journal Issue Volume 117, Numbers 1-6 / December, 1998
Feb
27
Vector bundles with a fixed determinant on an irreducible nodal curve
February 27, 2008 | Comments Off
Abstract LetM be the moduli space of generalized parabolic bundles (GPBs) of rankr and degree dona smooth curveX. LetM
−L
be the closure of its subset consisting of GPBs with fixed determinant− L. We define a moduli functor for whichM
−L
is the coarse moduli scheme. Using the correspondence between GPBs onX and torsion-free sheaves on a nodal curveY of whichX is a desingularization, we show thatM
−L
can be regarded as the compactified moduli scheme of vector bundles onY with fixed determinant. We get a natural scheme structure on the closure of the subset consisting of torsion-free sheaves
with a fixed determinant in the moduli space of torsion-free sheaves onY. The relation to Seshadri-Nagaraj conjecture is studied.
−L
be the closure of its subset consisting of GPBs with fixed determinant− L. We define a moduli functor for whichM
−L
is the coarse moduli scheme. Using the correspondence between GPBs onX and torsion-free sheaves on a nodal curveY of whichX is a desingularization, we show thatM
−L
can be regarded as the compactified moduli scheme of vector bundles onY with fixed determinant. We get a natural scheme structure on the closure of the subset consisting of torsion-free sheaves
with a fixed determinant in the moduli space of torsion-free sheaves onY. The relation to Seshadri-Nagaraj conjecture is studied.
- Content Type Journal Article
- DOI 10.1007/BF02829806
- Authors
- Usha N. Bhosle, Tata Institute of Fundamental Research Homi Bhabha Road 400 005 Mumbai India
- Journal Proceedings Mathematical Sciences
- Online ISSN 0973-7685
- Print ISSN 0253-4142
- Journal Volume Volume 115
- Journal Issue Volume 115, Number 4 / November, 2005
Feb
26
Using Flex Components
February 26, 2008 | Comments Off
Even though they’re based on one page, Flex applications can become very large. If you were to concentrate all the code in
the main application file, the resulting application would be difficult to maintain, and it would be impossible to reuse the
code and the debugging constructs. Fortunately, Flex supports a component-based development model, which enables the developer
to structure the code of the application in a logical way, subdividing it into different files. These external files can be
MXML or ActionScript files. When you develop an application with Flex, you use the MXML tag or ActionScript code to declare
the objects in the project. These objects are called components, so it is considered to be a componentbased framework.
the main application file, the resulting application would be difficult to maintain, and it would be impossible to reuse the
code and the debugging constructs. Fortunately, Flex supports a component-based development model, which enables the developer
to structure the code of the application in a logical way, subdividing it into different files. These external files can be
MXML or ActionScript files. When you develop an application with Flex, you use the MXML tag or ActionScript code to declare
the objects in the project. These objects are called components, so it is considered to be a componentbased framework.
- Content Type Book Chapter
- DOI 10.1007/978-1-4302-0424-4_2
- Book Flex Solutions
- DOI 10.1007/978-1-4302-0424-4
- Online ISBN 978-1-4302-0424-4
- Print ISBN 978-1-59059-876-4
Feb
26
Flex Security
February 26, 2008 | Comments Off
Security is a fundamental aspect in the development of an application, and different levels of security can be guaranteed
to each project—taking into consideration the interaction with data and remote calls.
to each project—taking into consideration the interaction with data and remote calls.
- Content Type Book Chapter
- DOI 10.1007/978-1-4302-0424-4_10
- Book Flex Solutions
- DOI 10.1007/978-1-4302-0424-4
- Online ISBN 978-1-4302-0424-4
- Print ISBN 978-1-59059-876-4