False Calls Research Articles

Interspecific audience effects on the alarm-calling behaviour of a kleptoparasitic bird.

Audience effects are increasingly recognized as an important aspect of intraspecific communication. Yet despite the common occurrence of interspecific interactions and considerable evidence that individuals respond to the calls of heterospecifics, empirical evidence for interspecific audience effects on signalling behaviour is lacking. Here we present evidence of an interspecific audience effect on the alarm-calling behaviour of the kleptoparasitic fork-tailed drongo (Dicrurus adsimilis). When foraging solitarily, drongos regularly alarm at aerial predators, but rarely alarm at terrestrial predators. In contrast, when drongos are following terrestrially foraging pied babblers (Turdoides bicolor) for kleptoparasitic opportunities, they consistently give alarm calls to both aerial and terrestrial predators. This change occurs despite no difference in the amount of time that drongos spend foraging terrestrially. Babblers respond to drongo alarm calls by fleeing to cover, providing drongos with opportunities to steal babbler food items by occasionally giving false alarm calls. This provides an example of an interspecific audience effect on alarm-calling behaviour that may be explained by the benefits received from audience response.

Selectivity Assessment of Noninvasive Glucose Measurements Based on Analysis of Multivariate Calibration Vectors

Selectivity is paramount for the successful implementation of noninvasive spectroscopic sensing for the painless measurement of blood glucose concentrations in people with diabetes. Selectivity issues are explored for different multivariate calibration models based on noninvasive near-infrared spectra collected from an animal model. Noninvasive near-infrared spectra are collected through a fiber-optic interface attached to a thin fold of skin on the back of an anesthetized laboratory rat while glucose levels are varied in a controlled manner. Partial least-squares (PLS) calibration models are generated from noninvasive spectra collected during a single, 2-hour blood glucose transient. Calibration vectors are compared for optimized PLS calibration models created with correct and incorrect assignments of glucose concentrations to each noninvasive spectrum. Although both PLS models appear functional and seem capable of predicting glucose concentrations accurately during this transient, only the model generated from correct glucose assignments gives a credible calibration vector. When correct glucose assignments are used, the PLS calibration vector matches the corresponding net analyte signal calibration vector. No similarity in these calibration vectors is evident when incorrect glucose assignments are used. Glucose-specific spectral information is present within noninvasive near-infrared spectra collected from a rat model using a transmission geometry. Apparently functional, yet incorrect, calibration models can be generated, and the propensity to create such false PLS calibration models calls into question the validity of past reports. An analysis of calibration vectors can provide valuable insight into the chemical basis of selectivity for multivariate calibration models of complex systems.

DNA bar coding and pyrosequencing to identify rare HIV drug resistance mutations

Treatment of HIV-infected individuals with antiretroviral agents selects for drug-resistant mutants, resulting in frequent treatment failures. Although the major antiretroviral resistance mutations are routinely characterized by DNA sequencing, treatment failures are still common, probably in part because undetected rare resistance mutations facilitate viral escape. Here we combined DNA bar coding and massively parallel pyrosequencing to quantify rare drug resistance mutations. Using DNA bar coding, we were able to analyze seven viral populations in parallel, overall characterizing 118 093 sequence reads of average length 103 bp. Analysis of a control HIV mixture showed that resistance mutations present as 5% of the population could be readily detected without false positive calls. In three samples of multidrug-resistant HIV populations from patients, all the drug-resistant mutations called by conventional analysis were identified, as well as four additional low abundance drug resistance mutations, some of which would be expected to influence the response to antiretroviral therapy. Methods for sensitive characterization of HIV resistance alleles have been reported, but only the pyrosequencing method allows all the positions at risk for drug resistance mutations to be interrogated deeply for many HIV populations in a single experiment.

Facultative response to a kleptoparasite by the cooperatively breeding pied babbler

In many cases of interspecific kleptoparasitism, hosts develop defensive behaviors to minimize the impact of kleptoparasites. Because vigilance and defensive behaviors are often costly, selection should favor hosts that adjust the amount of investment needed to minimize losses to kleptoparasitism. However, examples of such facultative responses are rare. Here, we investigate the response of cooperatively breeding pied babblers (Turdoides bicolor) to the drongo (Dicrurus adsimilis), an avian kleptoparasite that regularly follows pied babbler groups, often giving alarm calls to alert the group to predators but also occasionally giving false alarm calls in order to steal food items. We show that pied babbler response to drongos varies markedly according to babbler group size. In small groups, where there are few individuals available to act as sentinels, babblers sentinel less when a drongo is present and respond strongly to drongo alarm calls. However, in large groups, where there are many individuals available to participate in predator vigilance, babblers sentinel more often when a drongo is present, rarely respond to drongo alarm calls, and aggressively displace drongos, with a consequent decline in the number of successful kleptoparasitism events. This behavior represent a facultative response to a kleptoparasite according to the costs versus benefits of tolerating their presence.

Effects of Globin mRNA Reduction Methods on Gene Expression Profiles from Whole Blood

Excessive globin mRNA in whole blood RNA decreases transcript detection sensitivity and increases signal variation on microarrays. Hence, methods based on peptide nucleic acid inhibitory oligos and biotinylated DNA capture oligos have been developed to reduce globin mRNA. However, there is limited information about the effects of these two methods on gene expression profiles. Thus, we systematically compared the facility and effects of the two globin reduction methods on profile measurements from Jurkat cell line RNA with or without spiked globin mRNA and human blood RNA isolated using PAXgene collection tubes. We showed that the methods were efficient at increasing the sensitivity of transcript detection without loss of specificity, but neither method could recover a profile equivalent to that of an identical RNA sample without globin mRNA excesses. The capture oligo method had slightly better transcript detection sensitivity for cell line RNA, lowered signal variation for PAXgene RNA, and more similar profiles to controls than the inhibitory method. However, the capture method required larger amounts of initial high-quality RNA to yield sufficient cRNA amounts, and its procedures were more complex and time consuming than the inhibitory method. These results inform the selection of methods suitable for multicenter surveillance of gene expression profiles.

Normalization Using Weighted Negative Second Order Exponential Error Functions (NeONORM) Provides Robustness Against Asymmetries in Comparative Transcriptome Profiles and Avoids False Calls

Studies on high-throughput global gene expression using microarray technology have generated ever larger amounts of systematic transcriptome data. A major challenge in exploiting these heterogeneous datasets is how to normalize the expression profiles by inter-assay methods. Different non-linear and linear normalization methods have been developed, which essentially rely on the hypothesis that the true or perceived logarithmic fold-change distributions between two different assays are symmetric in nature. However, asymmetric gene expression changes are frequently observed, leading to suboptimal normalization results and in consequence potentially to thousands of false calls. Therefore, we have specifically investigated asymmetric comparative transcriptome profiles and developed the normalization using weighted negative second order exponential error functions (NeONORM) for robust and global inter-assay normalization. NeONORM efficiently damps true gene regulatory events in order to minimize their misleading impact on the normalization process. We evaluated NeONORM’s applicability using artificial and true experimental datasets, both of which demonstrated that NeONORM could be systematically applied to inter-assay and inter-condition comparisons.

The diagnostic impact of contrast-enhanced MRI in management of breast disease

For effective use, the diagnostic impact of contrast-enhanced breast MRI (CE MRI) needs to be quantified. This is a retrospective study of 441 women who have undergone CE MRI of the breast from 1 July 1997 to 25 March 2002. Indications for CE MRI studies were diagnostic in 176, monitoring chemotherapy in 126 and study of MRI screening for breast cancer (MARIBS) cases in 139. CE MRI results were confusing or incorrect in 6% of the diagnostic group, 13% of the chemotherapy group and 9% of the MARIBS group. In 18 of 38 of these cases CE MRI stimulated further tests to clarify a clinical query. CE MRI resulted in an increase in confidence or change in clinical plan in 46% of the diagnostic group, 72% of the chemotherapy group and 80% of the MARIBS group. In 44 of 283 of these, CE MRI caused a beneficial change in the clinical plan based on conventional radiology. CE MRI results in a positive diagnostic impact above conventional imaging in a clinically important proportion of patients, but gives some false calls in a smaller proportion (8.6%).

Screening women with a familial or genetic predisposition to breast cancer: costs and effects of alternative screening policies

Objective: Contrast-enhanced MRI of the breast has been one of the most controversial areas of MRI. Even though most investigators have, in selected indications, been able to improve accuracy by the additional use of contrast-enhanced MRI, its abuse has been feared not only because of increased costs for imaging, but also because of increased biopsy rates caused by false positive calls and because of errors caused by insufficient standardisation. In this article an overview is given of the present knowledge about contrast-enhanced MRI of the breast. Factors that influence the accuracy and reproducibility of contrast-enhanced MRI are analysed. Method: Factors that influence accuracy include: (1) technical factors that influence accuracy, e.g. slice thickness (partial volume effect), motion reduction, reduction of (cardiac) artifacts, dosage of contrast agent, choice of pulse sequence and echotime, and choice of the method for elimination of fat signal. (2) Hormonal factors (timing of the examination with reference to the menstrual cycle, hormonal replacement therapy). They influence accuracy and must be taken into account. (3) Interpretation guidelines-their choice influences sensitivity and specificity mostly inversely and the use of information from conventional imaging appears necessary. (4) Patient selection influences accuracy for statistical and for biological reasons. Results: Based on the present literature and on the experiences gathered in six German universities (> 12 000 examinations) an excellent sensitivity (> 98%) can be achieved for the combination of mammography and MRI. However, specificity strongly varies with the indications. Recommended indications include examination of breasts with impaired evaluation due to severe scarring, after silicon implants and in the dense breast, exclusion of multicentricity and search for primary tumor. Indications under investigation include high risk patients and strictly selected problem cases. Conclusion: If appropriately applied and used for selected indications, contrast-enhanced MRI may allow a significant diagnostic gain. In order to take advantage of the full potentials of contrast-enhanced MRI the development of commercially available biopsy coils is essential.

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Prostate-specific antigen (PSA) bounce and other fluctuations: Which biochemical relapse definition is least prone to PSA false calls? An analysis of 2030 men treated for prostate cancer with external beam or brachytherapy with or without adjuvant androgen deprivation therapy

To determine the false call (FC) rate for prostate-specific antigen (PSA) relapse according to nine different PSA relapse definitions after a PSA fluctuation (bounce) has occurred after external beam radiation therapy (EBRT) or brachytherapy, with or without adjuvant androgen deprivation therapy. An analysis of a prospective database of 2030 patients was conducted. Prostate-specific antigen relapse was scored according to the American Society for Therapeutic Radiology and Oncology (ASTRO), Vancouver, threshold + n, and nadir + n definitions for the complete data set and then compared against a truncated data set, with data subsequent to the height of the bounce deleted. The FC rate was calculated for each definition. The bounce rate, with this very liberal definition of bounce, was 58% with EBRT and 84% with brachytherapy. The FC rate was lowest with nadir + 2 and + 3 definitions (2.2% and 1.6%, respectively) and greatest with low-threshold and ASTRO definitions (32% and 18%, respectively). The ASTRO definition was particularly susceptible to FC when androgen deprivation therapy was used with radiation (24%). New definitions of biochemical non-evidence of disease that are more robust than the ASTRO definition have been identified. Those with the least FC rates are the nadir + 2 and nadir + 3 definitions, both of which are being considered to replace the ASTRO definition by the 2005 meeting of the Radiation Therapy Oncology Group-ASTRO consensus panel.

Reducing False Security Alarm Calls for Police Service: A Policy Research Note

False alarm calls are a substantial resource allocation problem for police administrators even though the issue tends not to be high profile. A panel design is utilized to describe how one municipal fine schedule affects the generation of false security alarm calls for police service by residential, commercial, and nonprofit property types. It was found that property type accounts for12% of the variation in annual false alarm generation and that, on average, false alarm production decreased substantially over time.

DNA-arrays with electrical detection: A label-free low cost technology for routine use in life sciences and diagnostics

Fast and highly parallel DNA analysis are essential for improved biomedical research and development. Currently fluorescence-based methods are state of the art in DNA microarray analysis. The necessity to modify the target DNA with labels is costly, laborious and requires skilled personnel. Moreover, false positive calls from unspecific adsorption are possible and it is difficult to discriminate perfect matching target sequences from those with a single mismatch. In this paper a new and simple electrochemical approach for hybridisation detection without the need of labelling the target DNA is described. The EDDA (Electrically Detected Displacement Assay) method uses a solution of short redox-labelled signalling oligonucleotides (oligonucleotides carrying a covalently attached redox active compound like ferrocene) to characterize the hybridisation state of label-free capture probe DNA immobilised on gold electrodes. The number of capture probes associated with signalling oligonucleotides is determined by chronocoulometry. This technique allows to separate the electrochemical response of capture probe associated signal probes from the response of freely diffusing signalling probes. In the absence of the complementary target sequences the redox-labelled signalling probes at the surface give rise to an instantaneous increase of the detection signal, while freely diffusing signalling probes show a significantly delayed response. Hybridisation with targets complementary to the capture probe displace the loosely associated signalling probes thereby decreasing the instantaneous signal. Besides an introduction to the EDDA technology, data validating the method for biological material will be presented and an outlook to the detection of single nucleotide polymorphisms (SNPs) is given.

Comparison of methods for pharmacogenomics: SNaPshot, SNPstream UHT, Nanogen, and RFLP

The inter-individual variation of response to cancer chemotherapy and radiation therapy has a substantial genetic component and is a subject of pharmacogenetic studies. Our goal is to develop assays to analyze selected single nucleotide polymorphisms (SNPs) in genes with proven relevance for pharmacogenetics. Today's research in the field needs technological platforms for which the demands both in terms of quality and throughput are high. Pharmacogenomics utilizes various genotyping techniques as well as gene-expression studies in studying the effect of different pharmaceuticals as well as the pathways that influence them. Here we provide an overview of the platforms currently in use, and discuss their efficiency, precision and technological stability. The amount of hands-on time needed and the cost-effectiveness are discussed. We also compared the success rate of several methods. SNaPshot is a homogeneous-phase-based primer extension method and SNPstream UHT is a solid-phase-based primer extension method. The Nanogen chip employs binding of a biotinylated probe to a chip coated with hydrogel enriched with streptavidin. This universal design presents the possibility to perform both genotyping as well as gene-expression experiments, even on the same chip. Results were compared with the classical enzymatic restriction enzyme fragment polymorphism (RFLP) assay. The initial set included eight SNPs in the X-ray cross-complementing group 1 protein, XRCC1; APEX nuclease (multifunctional DNA repair enzyme) 1, APEX1; multidrug resistance gene, MDR1; gluthation-S-transferase P1, GSTP1; and tumor protein p53, TP53. Functional SNPs in these genes have been shown to influence the therapeutic effect of a series of anti-cancer drugs such as 5-fluorouracyl, doxorubicin, etoposide, thioguanine and irinotekan. Three series of 36 breast cancer patients treated with 5-fluorouracyl and mitomycin, of 92 breast cancer patients treated with doxorubicin and of 109 control individuals have been genotyped. This resulted in 1527 genotypes. Of these, 391 had been analysed by SNaPshot, 900 by SNPstream UHT, 454 by Nanogen and 966 by RFLP. The success rate was 91% for SNaPshot, 97% for SNPstream UHT, 96% for Nanogen, and 99% for RFLP. When comparing the methods pairwise, the lowest variation was observed between SNPstream UHT and Nanogen (0.4%). SNPstream UHT and Nanogen had similar rates of discrepancy when compared with RFLP: 3.2% and 2.6%, respectively. Close re-analysis of those samples revealed false calls due to incomplete cutting during the RFLP. The highest observed dis-concordance observed was between SNaPshot and SNPstream UHT (8.9%). Careful evaluation of genotyping quality is needed both for large epidemiological studies and smaller clinical trials, and especially in prospective pharmacogenetic studies of separate individuals in clinical settings.

The Role of Alarms and CCTV in Detecting Non-residential Burglary

This study is concerned with the role of burglar alarms and CCTV in the detection of non-residential burglary. Funded by the UK Home Office's Policing and Reducing Crime Unit, it involves surveys of police officers, supplemented by police data, site surveys and victim interviews. Alarms and CCTV made important contributions to detecting burglaries, in terms of on-scene capture and arrests due to using eye-witness descriptions and filmed recordings for identifying offenders. There may be potential to increase numbers of detected cases by fitting more of both security devices, but this partly depends on patrol workloads, filtering out the bulk of false alarm calls and minimising the tendency for activated, audible alarms to reduce CCTV suspect recordings by prompting the burglar's flight. This might be best resolved either by fitting delayed-audible alarms or alarms that do not trigger on entry to premises, though this might result in goods being taken at more incidents, or by installing a combination of CCTV cameras on the outside of premises with alarms at entry points. Hidden CCTV also appears to be better than visible cameras for filming and identifying suspects. Implications of findings for research design are also considered.

Evaluation of alternative policies to combat false emergency calls

Ninety-four to ninety-nine percent of all police physical responses to burglar alarm activations are false. In 2000 police responded to 36 million false calls at an estimated cost of $1.8 billion. This paper presents and evaluates ten police policies for dealing with this waste of police resources. The paper then suggests that a public–private partnership will yield the highest net social benefits and avoids undesired cross subsidization. It further shows that implementation of a market oriented economic model where the police fulfill merely their public obligation is preferred to intuitive solutions that are often used by police.

An ultrasonic solution for second-layer crack detection

Eddy current methods often provide adequate crack detection in thin non-ferrous multi-layer structures such as aircraft fuselage skins. However, as the first layer becomes thicker, the second-layer crack detectability quickly becomes inadequate using eddy currents. This is the case in many aircraft wing structures where the structurally-critical spar flange is often hidden beneath a thick skin layer. For many years, ultrasonic methods have been ruled out due to the difficulty and unreliability of coupling the ultrasound into the second layer. Whilst this situation has not fundamentally changed, the improved adhesion and widespread use of sealants for corrosion protection. and to seal wing fuel tanks, has resulted in some opportunities for the use of ultrasound in the second layer of wing skins. Groups in the USA and Australia have developed techniques for second-layer crack detection using single-element angle probes and have evaluated the resulting probability of detection for their techniques. The NDE Group at QinetiQ has recently developed a method using an angled phased-array probe that can acquire full-waveform data in a fraction of the time. However, regardless of the acquisition method, the scans are somewhat complex to understand, so an automated analysis program has been developed to enhance the distinction between crack indications and potential false calls. This program also sentences each fastener hole using pass/maybe/fail criteria and attempts to size any crack that is found - based on calibration data from an EDM-notched specimen. This paper describes the difficulties of the complex analysis required and explains the methodology behind the automated analysis technique. Examples are given on EDM-notched real structures.

Determination of Pedestrian Push-Button Activation Duration at Typical Signalized Intersections

Recent advances in pedestrian push-button design, led by the development of accessible pedestrian signals (APSs), have created a new method of communicating traffic control information to pedestrians. Some APS devices have beaconing features or verbal (speech) message capabilities obtained by pressing and holding the pedestrian push button for approximately 3 s. Other features, such as the extension of the walk interval, may also be activated with an extended press of the push button. Recent research has suggested that 3 s may be excessive because it is hard for some users to hold the push button for this long. Additionally, most pedestrians may not hold the push button for this length of time. The problem lies in determining how long the APS push button should be pressed for a push-button information message or special accessibility features to be obtained. The primary objective of the research described in this paper was to develop a time distribution of typical pedestrian push-button activation durations. Data were obtained by attaching a voltage recorder to the pedestrian push-button circuit inside traffic signal controllers at eight locations in three cities in Wisconsin and Massachusetts. This device recorded the amount of time, to the nearest 1/100 of a second, that each pedestrian push button was pressed. A total of 1,439 push-button presses were recorded. The average push-button press duration was 0.2 s. More than 95% of all push-button presses recorded were less than 1.0 s. Only four push-button presses exceeded 3.0 s. The results show that the duration of an extended push-button press needed to obtain additional crossing information can be reduced to approximately 1 s without a significant number of false calls. A 1-s press will minimize the effort required for pedestrians to actuate special accessible features, while it will minimize unnecessary noise and vehicular traffic disruption.

Determination of Pedestrian Push-Button Activation Duration at Typical Signalized Intersections

Recent advances in pedestrian push-button design, led by the development of accessible pedestrian signals (APSs), have created a new method of communicating traffic control information to pedestrians. Some APS devices have beaconing features or verbal (speech) message capabilities obtained by pressing and holding the pedestrian push button for approximately 3 s. Other features, such as the extension of the walk interval, may also be activated with an extended press of the push button. Recent research has suggested that 3 s may be excessive because it is hard for some users to hold the push button for this long. Additionally, most pedestrians may not hold the push button for this length of time. The problem lies in determining how long the APS push button should be pressed for a push-button information message or special accessibility features to be obtained. The primary objective of the research described in this paper was to develop a time distribution of typical pedestrian push-button activation durations. Data were obtained by attaching a voltage recorder to the pedestrian push-button circuit inside traffic signal controllers at eight locations in three cities in Wisconsin and Massachusetts. This device recorded the amount of time, to the nearest 1/100 of a second, that each pedestrian push button was pressed. A total of 1,439 push-button presses were recorded. The average push-button press duration was 0.2 s. More than 95% of all push-button presses recorded were less than 1.0 s. Only four push-button presses exceeded 3.0 s. The results show that the duration of an extended push-button press needed to obtain additional crossing information can be reduced to approximately 1 s without a significant number of false calls. A 1-s press will minimize the effort required for pedestrians to actuate special accessible features, while it will minimize unnecessary noise and vehicular traffic disruption.

Use of signal thresholds to determine significant changes in microarray data analyses

The use of a constant fold-change to determine significant changes in gene expression has been widely accepted for its intuition and ease of use in microarray data analysis, but this concept has been increasingly criticized because it does not reflect signal intensity and can result in a substantial number of false positives and false negatives. To resolve this dilemma, we have analyzed 65 replicate Affymetrix chip-chip comparisons and determined a series of user adjustable signal-dependent thresholds which do not require replicates and offer a 95% confidence interval. Quantitative RT-PCR shows that such thresholds significantly improve the power to discriminate biological changes in mRNA from noise and reduce false calls compared to the traditional two-fold threshold. The user-friendly nature of this approach means that it can be easily applied by any user of microarray analysis, even those without any specialized knowledge of computational techniques or statistics. Noise is a function of signal intensity not only for Affymetrix data but also for cDNA array data, analysis of which may also be benefited by our methodology.

A study of operator performance in a visual NDT inspection task by remote video camera

In a performance demonstration test (PDT), ten operators inspected submerged ceramic plates for cracks, simulating inspection of internal components of water-cooled reactors. The demands in the present study were higher than what the procedure used was qualified for. Despite this, overall performance was good. For cracks covered by the original procedure (40 μm and wider) the performance was excellent for even the strictest criterion (>95% hits). The average number of false calls was only 7.8%. Performance did not decrease significantly with time. The operators were highly consistent in their assessments, more than 92% of the indications were given the same assessment by the same operator in the first and in the second half of the PDT. The operators considered not being under time pressure as an important prerequisite for good performance. Since the number of false calls were low, operators were recommended to use a more lenient criterion in order to reduce the number of misses. It was concluded that with reasonable demands on designated flaw-size, operators achieve high performance. Also, it was concluded that inspecting in two instalments could improve performance.