Factors affecting the determination of electrochemical noise resistance

The similarity between electrochemical noise resistance (Rn) and polarization resistance (Rp) has been confirmed in many laboratories, and a new method for corrosion rate determination has been developed based upon this similarity. However, this method remains controversial. Some researchers have reported experimental results that did not support a similarity between Rp and Rn. Other researchers have found that this similarity does not hold true for every system. To address this controversy, factors affecting the measurement and calculation of Rn were investigated. Several factors - including instrument noise, direct current (DC) trend, noise sampling rates, and noise sampling duration - can affect the accuracy of Rn determination signiftcantly and, in some cases, can cause disagreement between Rn and Rp. It was recommended that a system check be carried out to avoid the influence of these factors.

Locally sparsified compressive sensing for improved MR image qualtity

The fact that medical images have redundant information is exploited by researchers for faster image acquisition. Sample set or number of measurements were reduced in order to achieve rapid imaging. However, due to inadequate sampling, noise artefacts are inevitable in Compressive Sensing (CS) MRI. CS utilizes the transform sparsity of MR images to regenerate images from under sampled data. Locally sparsified Compressed Sensing is an extension of simple CS. It localises sparsity constraints for sub-regions rather than using a global constraint. This paper, presents a framework to use local CS for improving image quality without increasing sampling rate or without making the acquisition process any slower. This was achieved by exploiting local constraints. Localising image into independent sub-regions allows different sampling rates within image. Energy distribution of MR images is not even and most of noise occurs due to under-sampling in high energy regions. By sampling sub-regions based on energy distribution, noise artefacts can be minimized. Experiments were done using the proposed technique. Results were compared with global CS and summarized in this paper.

Discovery of stop regions for understanding repeat travel behaviors of moving objects

GPS trajectory dataset with high sampling-rates is usually in large volume that challenges the processing efficiency. Most of the data points on trajectories are useless. This paper summarizes trajectories using stop points. We define a new concept of stay stability (i.e., time dividing distance or reciprocal of speed) between any two GPS points to detect stop points on individual trajectories. We propose a novel Mining Repeat Travel Behaviors Using Stop Regions (MRTBUSR) method. In MRTBUSR, a stop region is a popular region containing a certain number of close stop points that can be grouped into a cluster. We then retrieve common sequences of stop regions to denote repeat route patterns and further analyze the stop durations on a stop region to find repeat travel behaviors. The experiments on 20 labeled trajectories selected from GeoLife demonstrated the semantic effect, accuracy and near linear efficiency of our proposed method.

Changes in catch rates and length and age at maturity, but not growth, of an estuarine plotosid (cnidoglanis macrocephalus) after heavy fishing

The hypothesis that heavy fishing pressure has led to changes in the biological characteristics of the estuary cobbler (Cnidoglanis macrocephalus) was tested in a large seasonally open estuary in southwestern Australia, where this species completes its life cycle and is the most valuable commercial fish species. Comparisons were made between seasonal data collected for this plotosid (eeltail catfish) in Wilson Inlet during 2005-08 and those recorded with the same fishery-independent sampling regime during 1987-89. These comparisons show that the proportions of larger and older individuals and the catch rates in the more recent period were far lower, i.e., they constituted reductions of 40% for fish ≥430 mm total length, 62% for fish ≥4 years of age, and 80% for catch rate. In addition, total mortality and fishing-induced mortality estimates increased by factors of ~2 and 2.5, respectively. The indications that the abundance and proportion of older C. macrocephalus declined between the two periods are consistent with the perception of long-term commercial fishermen and their shift toward using a smaller maximum gill net mesh to target this species. The sustained heavy fishing pressure on C. macrocephalus between 1987-89 and 2005-08 was accompanied by a marked reduction in length and age at maturity of this species. The shift in probabilistic maturation reaction norms toward smaller fish in 2005-08 and the lack of a conspicuous change in growth between the two periods indicate that the maturity changes were related to fishery-induced evolution rather than to compensatory responses to reduced fish densities.

Use of respiration rates of scyphozoan jellyfish to estimate their effects on the food web

One of the main objectives of research on jellyfish is to determine their effects on the food web. They are voracious consumers that have similar diets to those of zooplanktivorous fish, as well as eating microplankton and ichthyoplankton. Respiration rates (RRs) can be used to estimate the amount of food needed to balance metabolism, and thereby estimate minimum ingestion. We compiled RRs for scyphozoan medusae in three suborders (Semeaostomeae, Rhizostomeae, and Coronatae) to determine if a single regression could relate RRs to mass for diverse scyphomedusan species. Temperature (7–30°C) was not a significant factor. RRs versus wet weight (WW) regressions differed significantly for semeaostome and rhizostome medusae; however, RRs versus carbon mass over five-orders of magnitude did not differ significantly among suborders. RRs were isometric against medusa carbon mass, with data for all species scaling to the power 0.94. The scyphomedusa respiration rate (SRR) regression enables estimation of RR for any scyphomedusa from its carbon mass. The error of the SRR regression was ±72%, which is small in comparison with the 1,000-fold variation in field sampling. This predictive equation (RR in ml O2 d−1 = 83.37 * g C0.940) can be used to estimate minimum ingestion by scyphomedusae without exhaustive collection of feeding data. In addition, effects of confinement on RRs during incubation of medusae were tested. Large medusae incubated in small container volumes (CV) relative to their size (ratios of CV:WW < 50) had RRs ~one-tenth those of medusae in relatively larger containers. Depleted oxygen during incubation did not depress RRs of the medusae; however, swimming may have been restricted and respiration reduced in consequence. We briefly review other problems with RR experiments and suggest protocols and limitations for estimating ingestion rates of jellyfish from metabolic rates.

Response rates in Australian market research

RICA commissioned Deakin University to “establish whether response rates are in decline in the Australian market research industry and to identify, as far as possible, the reasons for these declines if they exist. This is likely to involve a review of previous research, a literature review and collection of data on response rates provided on a confidential basis and with the assistance of AMSRO to facilitate data provision.”

Attempts were made to contact all listed market research companies in Australia, including all major internet panel companies. While industry co-operation was not high with the study, sufficient data was provided to depict current response rates and to show how they had declined over time. Because of the low contactability issues, this Report proposes the use of better methods to compute the reliability of survey estimates by taking account of past survey results.

The literature review revealed a wealth of recent studies, with the main emphasis being on studies of telephone and internet surveys. This review of the research produced 34 evidence-based guidelines for social researchers. While some of these reflect current practice, the emergence of the internet as the main survey method raises a number of disclosure and sampling issues. Esomar (2012) has produced 28 issues to be raised with providers, which sets the basis for good industry practice. This suggests an opportunity for the industry to adopt these standards as its own and to conduct training courses for major clients and suppliers. There are many panel providers, some of whom are not AMSRO members. AMSRO may need to examine what role it can play in mandating or encouraging adherence to these standards as a way of promoting the industry.

Talks with key industry people, as well as the literature, have revealed the importance of blended surveys, where multiple contact and response mechanisms are used. Particularly where an internet panel is used as one source, this poses representativeness and weighting issues which are difficult to resolve. The Report recommends that where blended survey methods are used, measures be taken to measure contactability in the other contact media, along with more sophisticated weighting schemes. The industry should examine its training courses to ensure that industry expertise keeps pace with these developments.
Summary of Results

The results focus on two main collection methods – the telephone and the internet. As far as the telephone is concerned response rates have been in a gradual decline the last decade. This outcome is hard to detect because the data show considerable fluctuations from one survey wave to the next. Among cold-calling surveys, telephone response rates are typically below 10%, for a range of topics and survey types. Co-operation rates, (the ratio of obtained interviews to refusals) are typically below 0.2 (that is below one interview to five refusals). Telephone interviews with clients have a higher response rate – typically above 20% with co-operation rates above 1.0. It would appear that some topics, such as financial services, may induce a lower level of co-operation. Government sponsored surveys have higher response rates, at times over 50%, but even here a sharp decline in response rates over time for one long running monitor was observed. Co-operation rates were also higher in government sponsored surveys.

One long data series from a telephone omnibus suggested that the “Do Not Call Register” which began in May, 2007 had some positive effects for the industry. Initially there was a spike in both response rates and co-operation. Although this was relatively short-lived, response rates thereafter declined more slowly and co-operation rates were somewhat higher and remained stable. These conclusions should be regarded as tentative as more data series would really be necessary to see if similar trends occurred elsewhere.

As far as the internet is concerned, panel response rates are around the 20% mark and appear to be relatively stable over the last few years. In this case, the gross response rate is the number of interviews divided by the number of invitations sent. As the number of invitations may be a function of the need to fill a survey quickly, it should be considered a gross indicator of response. In order to capture this phenomenon, a further measure has been devised, termed the “attempt rate” which measures the percentage of people who attempt to participate once sent the invitation. The available data suggests that it is relatively stable. However, it is also somewhat susceptible to the time the survey was left open. Finally, a co-operation rate was also calculated. It measures the ratio of completed to terminated interviews, typically at least five interviews to each termination, but often much higher. This measure is not directly comparable with the co-operation rate in telephone surveys because it cannot take account of the number of eligible people on the panel who open the invitation, see the company doing the survey or its length and decide not to take the survey. For internet client studies, response rates were typically somewhat higher than shown for the panels, but there was marked variability.

There was only one study provided of intercept interviews. It showed response rates of over 60% and co-operation rates of nearly 2 interviews per refusal. A strength and a weakness of intercept interviewing is the ability to be selective in who is asked to participate. As for mail, one government sponsored mail survey from 2010 is reported, with a response rate over 50%. The previous review contains more data, as mail appears to be infrequently used within the industry for commercial surveys.

While surveys remain a major and highly effective tool for the industry and its clients, issues with contactability and co-operation mean that even closer attention is needed to survey design, sampling, weighting and analysis than was previously the case.