An Evaluation of Tricalcium Phosphate Excipients Particularly Using Instrumented Rotary and Single Station Tablet Presses

Two direct compression grades of tricalcium phosphate, Tri-Compress^R (Edward Mendell Co., Inc.) and Tri-Tab^R (Stauffer Chemical Co.), and a product containing tricalcium phosphate, D locust bean gum and citric acid, Loco-Tab^R (Ingredient Technology Corp.), were studied. Loco-Tab is composed of smaller particles having more irregularly shaped surfaces than the others. It is also less dense and somewhat less flowable than the other materials. None of these excipients lost weight at elevated temperature and none can be considered to be hygroscopic. Compressibility in formulations was studied using instrumented rotary and single station tablet presses. In all cases, the single station press yielded harder tablets at a given compression force. Dissolution of an insoluble drug was affected to a degree by the press used. Drug dissolution from Loco-Tab formulations was excellent at all tablet hardnesses, a highly desirable property for tablets to be coated using fluidized bed equipment. Loco-Tab would seem to be the calcium phosphate excipient of choice while recognizing that it is not a single entity and that it is acidic, in contrast to the neutral to slightly basic pH of the others.     

Revisiting free riding and the Tit-for-Tat in BitTorrent: A measurement study

In this paper we report new results of our continuous effort on analyzing the impact of incentive mechanisms on user behavior in BitTorrent. In this second measurement and analysis study we find that free riders’ population has significantly increased comparing to our previous measurement study. We relate this increase to the advance in end-users’ connection speeds and to users’ increased knowledge in BitTorrent. We also categorize free riders based on the behavior they exhibit in multiple-torrent system into three types: cheaters, strategic and lucky peers. Furthermore, refuting the findings of other studies, we show that peers who exploit the system in BitTorrent are both high bandwidth capacity peers and low bandwidth capacity peers. Moreover, we argue that the Tit-for-Tat mechanism does not discriminate peers based on their bandwidth capacities and that it reacts successfully against inter-class bandwidth capacity strategic peers. Finally, we propose a memory-backoff approach to the optimistic unchoke policy that reduces the volume of free riding in BitTorrent.

A SiGe BiCMOS analog SISO decoder with I/O interface

Although recent implementations of analog iterative decoders have proven their potential for higher decoding speed and less power consumption than their digital counterparts, the CMOS or conventional BiCMOS technologies used so far seem to be incapable to cope with the need for high throughput that high-speed applications require. Within this context this work presents the design and test results of a high-speed analog SISO (Soft-Input Soft-Output) channel decoder for an 8-bit trellis code by exploiting the high-speed features of SiGe heterojunction bipolar transistors (HBTs). It is one of the first successful implementations of an error-correcting decoder in SiGe BiCMOS technology, which incorporates a high-speed I/O interface. A high-level model of the mismatch effects indicates that there is no significant performance penalty. Moreover, simulations and performance evaluations of an analog Turbo decoder based on the designed SISO decoder are provided. Even though the IC of the SISO module was tested at a throughput up to 3 Mbps, simulation results show that the decoder is capable to operate at 50 Mbps. The measured power consumption is 860 mW and the die area is 3.4 × 3 mm².     

Robust multimodal audio–visual processing for advanced context awareness in smart spaces

Identifying people and tracking their locations is a key prerequisite to achieving context awareness in smart spaces. Moreover, in realistic context-aware applications, these tasks have to be carried out in a non-obtrusive fashion. In this paper we present a set of robust person-identification and tracking algorithms, based on audio and visual processing. A main characteristic of these algorithms is that they operate on far-field and un-constrained audio–visual streams, which ensure that they are non-intrusive. We also illustrate that the combination of their outputs can lead to composite multimodal tracking components, which are suitable for supporting a broad range of context-aware services. In combining audio–visual processing results, we exploit a context-modeling approach based on a graph of situations. Accordingly, we discuss the implementation of realistic prototype applications that make use of the full range of audio, visual and multimodal algorithms.     

A Lottery-based pricing scheme for peer-to-peer networks

Users in Peer-to-Peer (P2P) networks tend to exploit the maximum resources they are able to obtain, offering minimum resources in response. This behavior undermines the goal of P2P systems in spreading files through the network and imposes the concept of free-riding. In this paper we propose a Lottery-based pricing mechanism to enhance the sharing level in P2P networks and help increase the number of objects disseminated. The scheme is an extension of the traditional micropayment mechanism. Our scheme provides higher payoff for peers who contribute to the P2P network and higher cost for peers who act selfishly and choose not to share resources. We present simulation results to demonstrate the performance of the proposed mechanism.     

PainDroid: an android-based virtual reality application for pain assessment

Earlier studies in the field of pain research suggest that little efficient intervention currently exists in response to the exponential increase in the prevalence of pain. In this paper, we present an Android application (PainDroid) with multimodal functionality that could be enhanced with Virtual Reality (VR) technology, which has been designed for the purpose of improving the assessment of this notoriously difficult medical concern. PainDroid has been evaluated for its usability and acceptability with a pilot group of potential users and clinicians, with initial results suggesting that it can be an effective and usable tool for improving the assessment of pain. Participant experiences indicated that the application was easy to use and the potential of the application was similarly appreciated by the clinicians involved in the evaluation. Our findings may be of considerable interest to healthcare providers, policy makers, and other parties that might be actively involved in the area of pain and VR research.     

On the design of a privacy aware authorization engine for collaborative environments

Business networking has substantially reshaped common enterprise procedures and has paved the way for the development of ground-breaking information sharing patterns and inter-organizational cooperative practices. Yet, critical issues still stand unaddressed; privacy and sensitive information confidentiality implications threaten to diminish the economic and social benefits derived from online collaboration. Nevertheless, privacy preservation refers to a multidimensional and cross-disciplinary subject, accompanied by both legal as well as technical challenges. In this context, this paper describes the design of a privacy-aware decision engine operating within synergistic contexts. Decision making regarding the production of authorizations and information usage rules is founded on a detailed privacy context and the enforcement of a deductive reasoning algorithm. The proposed reasoning process spans two distinct phases, taking into account an a priori perspective of the system while at the same time maintaining responsiveness in dynamic contexts.     

Evaluation of in vitro percutaneous absorption of olanzapine and fluoxetine HCl: enhancement properties of olanzapine

The diffusion characteristics of fluoxetine HCl (FLX HCl) and olanzapine (OLZ) alone and in combination with each other were studied to determine their in vitro permeation behavior across a series of gelling agents through a cellulose membrane and human cadaver skin. Klucel 0.5% was selected as the optimal formulation to study their diffusion through human cadaver skin. The release profiles of drugs acting alone and in combinations were identical in the case of the cellulose membrane. However, with human cadaver skin, the permeation of FLX HCl in combination with OLZ drastically increased (732 μg) compared with the release of FLX HCl alone (43.7 μg), while the release of OLZ remained the same whether alone or in combination with FLX HCl (183.7 μg). The results indicate that OLZ enhances the diffusion of FLX HCl through the cadaver skin. Follow-up studies with OLZ were conducted to further investigate this phenomenon and have shown that OLZ enhancement properties are skin reversible as well as concentration dependent. Also, a variety of experiments with different hydrophilic and lipophilic molecules were conducted, and it was found that OLZ enhances the permeation of hydrophilic compounds, while it has no influence on lipophilic compounds. Finally, a number of compounds structurally related to OLZ were investigated as enhancers, and it was determined that piperazine ring attached to the tricyclic system of OLZ is essential for enhancement of FLX HCl (1,837 μg).