Effectiveness of Hindman's theorem for bounded sums

We consider the strength and effective content of restricted versions of Hindman's Theorem in which the number of colors is specified and the length of the sums has a specified finite bound. Let $\mathsf{HT}^{\leq n}_k$ denote the assertion that for each $k$-coloring $c$ of $\mathbb{N}$ there is an infinite set $X \subseteq \mathbb{N}$ such that all sums $\sum_{x \in F} x$ for $F \subseteq X$ and $0 < |F| \leq n$ have the same color. We prove that there is a computable $2$-coloring $c$ of $\mathbb{N}$ such that there is no infinite computable set $X$ such that all nonempty sums of at most $2$ elements of $X$ have the same color. It follows that $\mathsf{HT}^{\leq 2}_2$ is not provable in $\mathsf{RCA}_0$ and in fact we show that it implies $\mathsf{SRT}^2_2$ in $\mathsf{RCA}_0$. We also show that there is a computable instance of $\mathsf{HT}^{\leq 3}_3$ with all solutions computing $0'$. The proof of this result shows that $\mathsf{HT}^{\leq 3}_3$ implies $\mathsf{ACA}_0$ in $\mathsf{RCA}_0$

Review of The Electronic Transaction Ordinance: Can The Personal Identification Number Replace The Digital Signature?

In a recent consultation document, the Information Technology and Broadcasting Bureau proposed that personal identification numbers (PINs) be accepted as a form of signature for the purposes of the Electronic Transactions Ordinance (ETO) (Cap 553). This article explains why this proposal is fundamentally flawed. The article identifies three basic requirements for a signature and examines whether they are satisfied by digital signatures and PINs. It concludes that while a digital signature has built into it all the elements necessary for compliance with the requirements, a PIN can only be used for the purpose of authorisation and cannot be elevated to the status of a signature as required by the ETO.published_or_final_versio

Digital evidence search kit

With the rapid development of electronic commerce and Internet technology, cyber crimes have become more and more common. There is a great need for automated software systems that can assist law enforcement agencies in cyber crime evidence collection. This paper describes a cyber crime evidence collection tool called DESK (Digital Evidence Search Kit), which is the product of several years of cumulative efforts of our Center together with the Hong Kong Police Force and several other law enforcement agencies of the Hong Kong Special Administrative Region. We will use DESK to illustrate some of the desirable features of an effective cyber crime evidence collection tool. © 2005 IEEE.published_or_final_versio

Separable and anonymous identity-based key issuing

In identity-based (ID-based) cryptosystems, a local registration authority (LRA) is responsible for authentication of users while the key generation center (KGC) is responsible for computing and sending the private keys to users and therefore, a secure channel is required. For privacy-oriented applications, it is important to keep in secret whether the private key corresponding to a certain identity has been requested. All of the existing ID-based key issuing schemes have not addressed this anonymity issue. Besides, the separation of duties of LRA and KGC has not been discussed as well. We propose a novel separable and anonymous ID-based key issuing scheme without secure channel. Our protocol supports the separation of duties between LRA and KGC. The private key computed by the KGC can be sent to the user in an encrypted form such that only the legitimate key requester authenticated by LRA can decrypt it, and any eavesdropper cannot know the identity corresponding to the secret key. © 2005 IEEE.published_or_final_versio

Online health information seeking among people with diabetes mellitus and its association with self-management

Diabetes requires dedicated self-management to be able to achieve good control and outcome as this is a lifelong condition. The internet offers an amazing wealth of health information which may influence diabetes self-management. The aim of this study was to determine the prevalence of online health information seeking among people with diabetes and its associated factors. About 380 participants answered the online health information seeking questionnaire developed from literature search and expert panel review. Diabetes Self-Management was assessed using the Diabetes Self-Management Questionnaire (DSMQ). The prevalence of online health information seeking among people with diabetes was 38.4%. Common information sought included diabetes treatment (82.9%) lifestyle modification (77.4%) and diabetes prevention (67.3%). A large majority (93.1%) felt that the online information on diabetes was useful. Doctors and printed reading materials were the most common sources of information for diabetes (94.2% & 65.3%). Lower median age (59 years, IQR = 11), having a family member with diabetes, (COR = 1.188) tertiary education (COR = 6.037) and those who are employed (COR = 3.880) have higher odds of seeking online diabetes related health information. However, there was no significant association between online health information seeking and diabetes self-management. Prevalence of online health information seeking among people with diabetes was at an acceptable level. However, it was not associated with optimal diabetic self-management. Doctors and printed information remain as popular sources of information and hence should be maintained

Intrusion detection routers: Design, implementation and evaluation using an experimental testbed

In this paper, we present the design, the implementation details, and the evaluation results of an intrusion detection and defense system for distributed denial-of-service (DDoS) attack. The evaluation is conducted using an experimental testbed. The system, known as intrusion detection router (IDR), is deployed on network routers to perform online detection on any DDoS attack event, and then react with defense mechanisms to mitigate the attack. The testbed is built up by a cluster of sufficient number of Linux machines to mimic a portion of the Internet. Using the testbed, we conduct real experiments to evaluate the IDR system and demonstrate that IDR is effective in protecting the network from various DDoS attacks. © 2006 IEEE.published_or_final_versio

TOM40 Mediates Mitochondrial Dysfunction Induced by α-Synuclein Accumulation in Parkinson's Disease.

Alpha-synuclein (α-Syn) accumulation/aggregation and mitochondrial dysfunction play prominent roles in the pathology of Parkinson's disease. We have previously shown that postmortem human dopaminergic neurons from PD brains accumulate high levels of mitochondrial DNA (mtDNA) deletions. We now addressed the question, whether alterations in a component of the mitochondrial import machinery -TOM40- might contribute to the mitochondrial dysfunction and damage in PD. For this purpose, we studied levels of TOM40, mtDNA deletions, oxidative damage, energy production, and complexes of the respiratory chain in brain homogenates as well as in single neurons, using laser-capture-microdissection in transgenic mice overexpressing human wildtype α-Syn. Additionally, we used lentivirus-mediated stereotactic delivery of a component of this import machinery into mouse brain as a novel therapeutic strategy. We report here that TOM40 is significantly reduced in the brain of PD patients and in α-Syn transgenic mice. TOM40 deficits were associated with increased mtDNA deletions and oxidative DNA damage, and with decreased energy production and altered levels of complex I proteins in α-Syn transgenic mice. Lentiviral-mediated overexpression of Tom40 in α-Syn-transgenic mice brains ameliorated energy deficits as well as oxidative burden. Our results suggest that alterations in the mitochondrial protein transport machinery might contribute to mitochondrial impairment in α-Synucleinopathies

Enterprise resource planning adoption: structural equation modeling analysis of antecedents

This study identifies the key antecedent factors for accomplishing the adoption stage of enterprise resource planning (ERP) systems. Five potential antecedent factors of adoption were derived from the literature, including that on innovation theories, and data were obtained from a sample of 217 organizations across Australia. A structural equation modeling (SEM) technique was used to examine the complex relationships between antecedents and the adoption decision. We found that there were three positive drivers of a successful outcome of the ERP adoption stage. Prior findings have shown that system quality is a key enabler for innovation adoption by individuals, and we found that system quality is also an important driver for organizational adoption of ERP. It was also indicated that organizations consider adopting ERP when the market and customer patterns are relatively stable rather than in turbulent environments.Jiwat Ram, David Corkindale and Ming-Lu Wuhttp://www.iacis.org/jcis/jcis_toc.php?volume=54&issue=

Rhabdovirus Matrix Protein Structures Reveal a Novel Mode of Self-Association

The matrix (M) proteins of rhabdoviruses are multifunctional proteins essential for virus maturation and budding that also regulate the expression of viral and host proteins. We have solved the structures of M from the vesicular stomatitis virus serotype New Jersey (genus: Vesiculovirus) and from Lagos bat virus (genus: Lyssavirus), revealing that both share a common fold despite sharing no identifiable sequence homology. Strikingly, in both structures a stretch of residues from the otherwise-disordered N terminus of a crystallographically adjacent molecule is observed binding to a hydrophobic cavity on the surface of the protein, thereby forming non-covalent linear polymers of M in the crystals. While the overall topology of the interaction is conserved between the two structures, the molecular details of the interactions are completely different. The observed interactions provide a compelling model for the flexible self-assembly of the matrix protein during virion morphogenesis and may also modulate interactions with host proteins

Valacyclovir in the treatment of acute retinal necrosis

Background: To report the outcome of oral valacyclovir as the sole antiviral therapy for patients with acute retinal necrosis (ARN). Methods: This study reports a retrospective, interventional case series of nine consecutive patients with ten eyes with newly diagnosed ARN treated with oral valacyclovir as the sole antiviral agent. Eight patients received oral valacyclovir 2 g tid (Valtrex, GlaxoSmithKline) and one patient with impaired renal function received oral 1 g tid. The main outcome measures were response to treatment, time to initial response to treatment, time to complete resolution of retinitis, best corrected visual acuity (BCVA) at final follow-up, retinal detachment and development of recurrent or second eye disease. Results: Retinitis resolved in ten of ten (100%) affected eyes. The median time to initial detectable response was seven days and the median time to complete resolution was 21 days. A final BCVA of 20/40 or better was achieved in 6/10 (60%) of eyes. 3/10 eyes (30%) developed a retinal detachment. No patients developed either disease reactivation or second eye involvement over the course of the study (mean follow up 31 weeks, range 7 to 104 weeks). Conclusions: Treatment with oral valacyclovir as the sole antiviral therapy resulted in complete resolution of retinitis. Final BCVA and retinal detachment rate were comparable with previously reported outcomes for intravenous acyclovi