184,620 research outputs found
#Bieber + #Blast = #BieberBlast: Early Prediction of Popular Hashtag Compounds
Compounding of natural language units is a very common phenomena. In this
paper, we show, for the first time, that Twitter hashtags which, could be
considered as correlates of such linguistic units, undergo compounding. We
identify reasons for this compounding and propose a prediction model that can
identify with 77.07% accuracy if a pair of hashtags compounding in the near
future (i.e., 2 months after compounding) shall become popular. At longer times
T = 6, 10 months the accuracies are 77.52% and 79.13% respectively. This
technique has strong implications to trending hashtag recommendation since
newly formed hashtag compounds can be recommended early, even before the
compounding has taken place. Further, humans can predict compounds with an
overall accuracy of only 48.7% (treated as baseline). Notably, while humans can
discriminate the relatively easier cases, the automatic framework is successful
in classifying the relatively harder cases.Comment: 14 pages, 4 figures, 9 tables, published in CSCW (Computer-Supported
Cooperative Work and Social Computing) 2016. in Proceedings of 19th ACM
conference on Computer-Supported Cooperative Work and Social Computing (CSCW
2016
A flight dynamics investigation of compound helicopter configurations
Compounding has often been proposed as a method to increase the maximum speed of the helicopter. There are two
common types of compounding known as wing and thrust compounding. Wing compounding offloads the rotor at
high speeds delaying the onset of retreating blade stall, hence increasing the maximum achieveable speed, whereas
with thrust compounding, axial thrust provides additional propulsive force. The concept of compounding is not new
but recently there has been a resurgence of interest in the configuration due to the emergence of new requirements
for speeds greater than those of conventional helicopters. The aim of this paper is to investigate the dynamic stability
characteristics of compound helicopters and compare the results with a conventional helicopter. The paper discusses
the modelling of two compound helicopters, with the first model featuring a coaxial rotor and pusher propeller. This
configuration is known as the coaxial compound helicopter. The second model, known as the hybrid compound helicopter, features a wing and two propellers providing thrust compounding. Their respective trim results are presented
and contrasted with a baseline model. Furthermore, using a numerical differentiation technique, the compound models are linearised and their dynamic stability assessed. The results show that the frequency of the coaxial compound
helicopter’s dutch roll mode is less than that of the baseline helicopter and there is also greater roll damping. With
regards to the hybrid compound helicopter the results show greater heave damping and the stabilisation of the phugoid
due to the addition of the wing and propellers
Analysis of Compounded Pharmaceutical Products to Teach the Importance of Quality in an Applied Pharmaceutics Laboratory Course
Objective. To assess the effectiveness of a product-analysis laboratory exercise in teaching students the importance of quality in pharmaceutical compounding. Design. Second-year pharmacy students (N=77) participated in a pharmaceutical compounding laboratory exercise and subsequently analyzed their final product using ultraviolet (UV) spectrometry. Assessment. Reflection, survey instruments, and quiz questions were used to measure how well students understood the importance of quality in their compounded products. Product analysis showed that preparations compounded by students had an error range of 0.6% to 140%, with an average error of 23.7%. Students’ reflections cited common sources of error, including inaccurate weighing, contamination, and product loss during both the compounding procedure and preparation of the sample for analysis. Ninety percent of students agreed that the exercise improved their understanding of the importance of quality in compounded pharmaceutical products. Most students (85.7%) reported that this exercise inspired them to be more diligent in their preparation of compounded products in their future careers. Conclusion. Integrating an analytical assessment during a pharmaceutical compounding laboratory can enhance students’ understanding of quality of compounded pharmaceutical products. It can also provide students a chance to reflect on sources of error to improve their compounding technique in the future
Characterization and biodegradation of poly (vinyl alcohol)/cassava starch
A series of poly (vinyl alcohol)/cassava starch (PVA/CS) blends at 50, 60, 70 and 80 wt.% cassava starch contents were prepared in one-step compounding process. One step compounding means, all blends were compound together without solely plasticized PVA or cassava starch at beginning. All blends were characterized and testing accordingly. In this research, comparison between one-step compounding and two-step compounding (plasticized PVA/CS at the beginning) were tested by tensile strength. It shows that their tensile strengths were comparatively higher than the two-step compounding process of PVA/CS blends. In term of impact test, it indicates that CS acts as non-reinforcing filler. The compatibility of PVA/CS represents the similarity functional group and possess same polar group. Studies on thermal stability and crystallinity shows, increasing the cassava starch loading in PVA matrix, has reduced the enthalpy of melting point as well as degree of crystallinity. The onset degradation had shifted to a higher temperature when a higher percentage of cassava starch was used in PVA matrix. This is due to cyclic hemiacetal had been introduced into PVA blend by cassava starch. It resist to thermal attack. In biodegradability test, several factors have been determined to evaluate the rate of biodegradation. Increase the humidity as well as increasing the cassava starch loading in PVA matrix will improve the susceptibility contact of microorganism onto the surface of PVA/CS blend. Aspergillus Oryzae had been selected as a good reagent used to degrade the sample of PVA/CS blend compared to Bacillus Amyloliquefaciens and effective microorganism. The biodegradation process of PVA/CS blends in anaerobic condition is much more faster compared to aerobic conditions
Utilization of waste heat in trucks for increased fuel economy
Improvements in fuel economy for a broad spectrum of truck engines and waste heat utilization concepts are evaluated and compared. The engines considered are the diesel, spark ignition, gas turbine, and Stirling. The waste heat utilization concepts include preheating, regeneration, turbocharging, turbocompounding, and Rankine engine compounding. Predictions were based on fuel-air cycle analyses, computer simulation, and engine test data. The results reveal that diesel driving cycle performance can be increased by 20% through increased turbocharging, turbocompounding, and Rankine engine compounding. The Rankine engine compounding provides about three times as much improvement as turbocompounding but also costs about three times as much. Performance for either is approximately doubled if applied to an adiabatic diesel
The compounding of short fibre reinforced thermoplastic composites
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.It is generally accepted that the mechanical properties of short fibre reinforced thermoplastics do not correspond with the high mechanical properties of fibres used to reinforce them.
A study is made into the methods of compounding reinforcing fibres into thermoplastics to produce short fibre reinforced thermoplastics of enhanced properties.
The initial method chosen for investigation is the twin screw extrusion compounding process. Variables such as fibre feeding arrangement and extrusion screw design are found to be factors influencing the properties of carbon and glass reinforced nylon 6,6. Use is made of computer programs to predict properties, assess compound quality and estimate fibre-matrix bond strength.
Investigations indicate that the presence of reinforcing fibres with enhanced lengths does not result in the predicted property increases. The reasons for this shortfall are believed to lie in unfavourable fibre orientation in injection mouldings and the reduced strain to break of these materials.
Short Kevlar reinforced thermoplastics are compounded and their mechanical properties assessed. The reasons for the poor mechanical properties for these materials are identified as a poor bond strength between fibre and matrix, the formation of points of weakness within the fibres by the compounding and moulding processes and the coiled arrangement of fibres present in injection mouldings.
A method suitable for the routine assessment of fibre-matrix bond strength is used to examine combinations of fibre and thermoplastic matrix. A comparison is made of the values derived from this method with values calculated from stress-strain curves of injection mouldings. This allows an understanding of the nature of the fibre-matrix bond yielded by compounding and injection moulding steps.
A description is given of a novel method designed to overcome the limitations of conventional compounding routes to produce long fibre reinforced injection moulding feedstock. Further work is necessary before this method is a feasible production technique
Frequency and Severity of Neutropenia Associated with Food and Drug Administration Approved and Compounded Formulations of Lomustine in Dogs with Cancer.
BackgroundCompounded lomustine is used commonly in veterinary patients. However, the potential variability in these formulations is unknown and concern exists that compounded formulations of drugs may differ in potency from Food and Drug Administration (FDA)-approved products.Hypothesis/objectivesThe initial objective of this study was to evaluate the frequency and severity of neutropenia in dogs treated with compounded or FDA-approved formulations of lomustine. Subsequent analyses aimed to determine the potency of lomustine obtained from several compounding pharmacies.AnimalsThirty-seven dogs treated with FDA-approved or compounded lomustine.MethodsDogs that received compounded or FDA-approved lomustine and had pretreatment and nadir CBCs performed were eligible for inclusion. Variables assessed included lomustine dose, neutrophil counts, and severity of neutropenia. Lomustine 5 mg capsules from 5 compounding sources were tested for potency using high-pressure liquid chromatography (HPLC) with ultraviolet (UV) detection.ResultsTwenty-one dogs received FDA-approved lomustine and 16 dogs were treated with lomustine prescribed from a single compounding pharmacy. All dogs treated with FDA-approved lomustine were neutropenic after treatment; 15 dogs (71%) developed grade 3 or higher neutropenia. Four dogs (25%) given compounded lomustine became neutropenic, with 2 dogs (12.5%) developing grade 3 neutropenia. The potency of lomustine from 5 compounding pharmacies ranged from 50 to 115% of the labeled concentration, with 1 sample within ±10% of the labeled concentration.Conclusions and clinical importanceThese data support broader investigation into the potency and consistency of compounded chemotherapy drugs and highlight the potential need for greater oversight of these products
The Term Structure of Interest Rates
This paper consolidates and interprets the literature on the term structure, as it stands today. Definitions of rates of return, forward rates and holding returns for all time intervals are treated here in a uniform manner and their interrelations, exact or approximate, delineated. The concept of duration is used throughout to simplify mathematical expressions. Continuous compounding is used where possible, to avoid arbitrary distinctions based on compounding assumptions. Both the theoretical and the empirical literature are treated. The attached tables by J. Huston McCulloch give term structure data for U. S. government securities 1946-1987. The tables give discount bond yields, forward rates and par bond yields as defined in the paper. The data relate to the concepts in the paper more precisely than does any previously published data series.
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