323,947 research outputs found
Design of experiments methodology in studying near-infrared spectral information of model intact tablets : simultaneous determination of metoprolol tartrate and hydrochlorothiazide in solid dosage forms and powder compressibility assessment using near-infrared spectroscopy
No full textNear-infrared spectroscopy (NIRS) is applied in pharmaceutical industry for monitoring drug content during tablet manufacturing process. NIRS method, once developed and validated, is used over years and it is of critical importance to insure method robustness towards formulation, process, instrumental, acquisition and environmental factors. Design of Experiments (DoE) methodology was proposed in this work for systematic study of the effect of compression pressure, pre-compression pressure and tableting speed on Average Euclidean Distance (AED) which reflects NIR spectral features of the studied caffeine tablets, and Root Mean Squared Error of Prediction (RMSEP) as a key performance indicator of the developed NIRS calibration model for caffeine content prediction. Study was performed in diffuse reflectance (DR) and diffuse transmittance (DT) measurement mode. Tableting factors shown to have significant influence on the studied responses have been considered in the development of the robust calibration models in DR and DT mode, using Global Calibration Model (GCM) approach. Three studied factors have shown to be significant in DR mode whereas, compression pressure and tableting speed have shown significant effect on the studied responses in DT mode. Developed robust method in DT mode have shown superior performances compared to DR mode, exhibiting total error (RMSEP) of 1.21 % calculated on the independent test set. DoE setup, with the selection of factors and responses adopted in this study was not reported elsewhere.
Simultaneous NIRS quantification of two APIs in powders and tablets requires several challenges to be overcome. Overlapping absorption peaks of formulation components result in method specificity problem. Strategy for selecting the samples used for developing the prediction models is needed. Robustness of the method towards formulation factors needs to be assessed due to complex formulation. Fast and simple method for simultaneous quantification of Hydrochlorothiazide (HTZ) and Metoprolol Tartrate (MTP) in powders and tablets was proposed in work. Simulation of industrial scale tablet machine using tablet press replicator - Presster® was proposed as fast and cost-effective alternative for design and manufacture of tablet sets needed for NIRS calibration model development. Balance Reference Method (BRM) was proposed as an alternative to HPLC and UV-spectroscopy which are traditionally used as reference methods in NIRS model development. The proposed experimental setup was suggested for the feasibility study stage of the method development. The two model drugs were simultaneously quantified using NIRS exhibiting RMSEP of 1.69 and 1.31 mg in HTZ powder and tablet samples respectively, while MTP powder and tablet samples were predicted with RMSEP of 3.15 and 3.00 mg respectively. NIRS analysis of Metoprolol Tartrate and Hydrochlorothiazide in powders and tablets was not yet reported in the literature.
The compressibility and compatibility of a powder formulation is conventionally determined by compaction followed by destructive tensile strength and relative density measurement of the final compact. In this study, a non-destructive near-infrared spectroscopic (NIRS) was evaluated for the determination of powder compressibility and compactibility. Twelve different formulations were investigated with 2 batches produced per formulation. Relative density and tensile strength were measured using a traditional, destructive method on one tablet batch and subsequently by a developed non-destructive chemometric NIRS method on the second batch of the particular formulation. The outcomes of the two approaches were compared to validate the developed method. All data sets were fitted to the three established mathematical equations to calculate equation factors, which represent a formulation compressibility and compactibility. The study focus was set on the equation factor comparison between the traditional and the newly designed method. The results have shown a high degree similarity between the outcomes of the two methods. A discrepancy between the two methods was observed for the outcomes of the equation factors after fitting to Leuenberger equation. The approach using NIRS is suggested as a promising tool for monitoring tablet manufacturing process
Representation of Spectral Profiles in the Auditory System Part II: A Ripple Analysis Model
No full textBased on experimental results presented in [Vranic-Sowers and Shamma, 1993], and on further physiological and psychoacoustical evidence, it is argued that the auditory system analyzes a spectral profile along two largely independent dimensions. They correspond to the magnitude and phase of a localized Fourier transformation of the profile, closely analogues to the spatial frequency transformations described in the visual system. Within this general framework, a model of profile analysis is proposed in which a spectral profile is assumed to be represented by a weighted sum of sinusoidally modulated spectra (ripples). The analysis is performed by a bank of bandpass filters, each tuned to a particular ripple frequency and ripple phase. The parameters of the model are estimated using data from ripple detection experiments in [Green, 1986; Hillier, 1991]. Perceptual thresholds are then computed from the filter outputs and compared with thresholds measured for peak profile experiments, and for detection tasks with step, single component increment, and the alternating profiles
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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No full textCan archives of audiovisual TV interviews be used to make authors more visible to students, and thereby reduce the learning gap between native and non-native language speakers in college classes? We examined students in a college course who learned about one scholar's ideas through watching an audiovisual TV interview (i.e., visible author format) and about another scholar's ideas through reading a formal text description (i.e., invisible author format). For the invisible author, native language speakers scored significantly higher than the non-native language speakers on a corresponding exam question (i.e., a cognitive measure), generated more words on the exam question (i.e., a motivational measure), and mentioned the author's name more often in answering the exam question (i.e., an affective measure). For the visible author, the groups did not differ on any of these measures. These findings provide evidence for the idea that making the author visible through audiovisual TV interviews can eliminate the learning gap between native and non-native language speakers. 3 Universities around the world serve students who are non-native speakers of th
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
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