Use Of Iris Research Articles

The Genus <i>Iris</i> (Iridaceae) in Russia: Phytochemistry, Biological Activity and Application in Traditional Medicine

The genus Iris in Russia is represented by 41 species, of which 4 species are endemic, 11 are included in the Red Book of the Russian Federation and 30 have various regional conservation status. The review provides information on the phytochemical compounds, biological activity and medicinal properties of 16 species growing in Russia, and on their use in traditional medicine of different peoples. The analysis of available data shows that studying the component composition, biological activity levels, and medicinal use of Iris L. species requires their correct identification and the knowledge concerning their geographical distribution, ecology, and morphological characteristics. The use of Iris species in traditional medicine is described. The extracts and compounds isolated from the most of the studied species exhibit analgesic, antioxidative, antipyretic, anti-inflammatory, antibacterial and antimicrobial activity. Some species also have cytotoxic, antitumor, antidiabetic, anti-influenza, neuroprotective, antihyperglycemic, antiallergic, antifeedant and other properties. Most of the isolated metabolites were flavonoids, isoflavonoids, anthocyanes, terpenoids, xantgones, quinones, phenolic and fatty acids. In official and traditional medicine in Asia and Europe, the underground and aboveground parts of Iris aphylla, I. lactea, I. pseudacorus, I. ruthenica, I. sanguinea and other species of the genus are used. The article results from the long-term studies of irises in situ and in the collections of two botanical gardens, as well as extensive examination of literature on the component composition and medicinal properties of the studied species.

Easy-to-assemble and high quality-factor ESIW filter with post-based soldered inverters in X-band

Empty Substrate Integrated Waveguide (ESIW) devices maintain a compromise between the advantages of classical waveguide technologies, such as high quality factor and low losses, and the advantages of planar ones, like low cost and easy compact integration. Compared with SIW, since ESIW is not dielectric filled, additional advantages are achieved, such as lower insertion losses and resonators with higher quality factor. In recent years several filters and folded filters have been designed in ESIW, using all of them resonators based on irises. An alternative to the use of irises is H-plane cylindrical posts. Although cylindrical posts have been widely used in other technologies like Rectangular Waveguide, SIW or AFSIW, it is the first time that this kind of inverters has been used in ESIW. In this paper, the use of posts in ESIW is proposed and validated through the design and manufacture of a bandpass filter in X-band. Posts are soldered to top and bottom layers after ESIW is assembled, being this kind of filters easier to manufacture and more robust than those based on irises. The designed filter achieves return losses higher than 12 dB and insertion losses lower than 1.6 dB (considering microstrip-to-ESIW transitions) and a quality factor of 918.74.

The validity and reliability of a novel isotope ratio infrared spectrometer to quantify 13C enrichment of expired breath samples in exercise.

The traditional method to measure 13CO2 enrichment in breath involves isotope ratio mass spectrometry (IRMS), which has several limitations such as cost, extensive training, and large space requirements. Here, we present the validity and reliability data of an isotope ratio infrared spectrometer (IRIS)-based method developed to combat these limitations. Eight healthy male runners performed 105 min of continuous running on a motorized treadmill while ingesting various carbohydrate beverages enriched with 13C and expired breath samples were obtained every 15 min in triplicates. A total of 213 breath samples were analyzed using both methods, whereas 212 samples were repeated using IRIS to determine test-retest reliability. Bland-Altman analysis was performed to determine systematic and proportional bias, and intraclass correlation coefficient (ICC) and coefficient of variation (CV) to assess level of agreement and magnitude of error. The IRIS method demonstrated a small but significant systematic bias to overestimate δ13CO2 (0.18‰; P < 0.05) compared with IRMS, without any proportional bias or heteroscedasticity and a small CV (0.5%). There was a small systematic bias during the test-retest of the IRIS method (-0.07‰; P < 0.05), no proportional bias, an excellent ICC (1.00), and small CV (0.4%). The use of the Delta Ray IRIS to determine 13C enrichment in expired breath samples captured during exercise has excellent validity and reliability when compared with the gold standard IRMS.NEW & NOTEWORTHY The use of IRIS to determine 13C enrichment in expired breath samples captured during exercise to determine exogenous glucose oxidation during exercise has excellent validity and reliability when compared with the gold standard IRMS.

Iris pattern recognition as an infallible mean of identity establishment in forensic casework

Biometrics is a mean of forensic recognition based on me as ureme nts an d calculat ions o f human bo dy or biological features. Human body features. Biometric identification systems may make use of iris, retina, fingerprints, face, ear, gait parameters, facial physiognomy, photogrammetric or geometry features, etc. for recognition and hence identification pursuits. The high security areas like airports, nuclear reactors, thermal or hydro-electric power plants, legislative buildings, defense establishments etc., require secured entry of authorized persons. Biometric tools of recognition like automatic face recognition system can play a crucial role in recognizing illegal intruders to such areas. Iris is an excellent trait to be used in biometric system for recognition of an individual due to its individualistic, unique, universal and inimitable features. In this article, the current national and international status of use of iris patterns forforensic recognition, its advantages and limitations, and future prospects have been presented.

An Identity-Based Secure and Optimal Authentication Scheme for the Cloud Computing Environment

Security is a critical issue in cloud computing (CC) because attackers can fabricate data by creating, copying, or deleting data with no user authorization. Most of the existing techniques make use of password-based authentication for encrypting data. Password-based schemes suffer from several issues and can be easily compromised. This paper presents a new concept of hybrid metaheuristic optimization as an identity-based secure and optimal authentication (HMO-ISOA) scheme for CC environments. The HMO-ISOA technique makes use of iris and fingerprint biometrics. Initially, the HMO-ISOA technique involves a directional local ternary quantized extrema pattern–based feature extraction process to extract features from the iris and fingerprint. Next, the features are fed into the hybrid social spider using the dragon fly algorithm to determine the optimal solution. This optimal solution acts as a key for an advanced encryption standard to encrypt and decrypt the data. A central benefit of determining the optimal value in this way is that the intruder cannot determine this value. The attacker also cannot work out which specific part of the fingerprint and iris feature values are acted upon as a key for the AES technique. Finally, the encrypted data can be saved in the cloud using a cloud simulator. Experimental analysis was performed on five fingerprint and iris images for a man-in-the-middle attack. The simulation outcome validated that the presented HMO-ISOA model achieved better results compared with other existing methods.

Gender and survival benefit from initial irinotecan in metastatic colorectal cancer: Analysis of the XELAVIRI (AIOKRK0110) study.

3559 Background: XELAVIRI compared initial vs sequential irinotecan (iri) in combination with fluoropyrimidine (FP) plus bevacizumab (bev) in patients (pts) with mCRC, trial identification: NCT01249638. In the full analysis set of the study, non-inferiority of time to failure of strategy (TFS) was not shown (primary endpoint). Pts with RAS/BRAF wildtype (wt) tumors benefitted from initial iri. Methods: The study endpoints objective response rate (ORR), progression-free survival (PFS), time to failure of strategy (TFS) as well as overall survival (OS) were evaluated in female vs. male pts as well as molecular subgroups (i.e. RAS mutational status). Interaction of treatment and gender was tested by likelihood ratio tests. Results: Of 421 patients, 281/140 were male/female. In male patients, ORR was 33.6% without and 58.3% with initial iri (P &lt; 0.001). PFS (HR: 0.54 (95%CI 0.42-0.69) P &lt; 0.001) and OS (HR: 0.63 (95%CI 0.47-0.85), P = 0.002), were also significantly better with initial iri. In the subgroup analysis, this effect was especially pronounced in pts with RAS/BRAF wt tumors. In female pts, ORR was 43% in both arms, PFS was similar (HR: 1.09 (95%CI 0.76-1.55), P = 0.65) without and with initial iri. In OS, a strong trend for inferior outcome with initial iri was seen (HR: 1.46 (95%CI 0.95-2.24), P = 0.08) that reached significance in the multivariate analysis (HR: 1.73 (95%CI 1.04-2.86, P = 0.034). Female patients with RAS/BRAF wt tumors did not benefit from initial iri (HR 1.05 (95% CI 0.46-2.41), P = 0.903 for OS). Formal interaction of treatment and gender was seen for ORR (P = 0.018), PFS (P = 0.002) and OS (P = 0.001). There were some trends for more pronounced toxicities in female pts treated with Irinotecan. Conclusions: This unplanned exploratory analysis suggests that gender might interact with efficacy of initial iri when used in the context of FP and bev. While especially male RAS wild-type patients derived a significant and clinically meaningful benefit from initial use of iri, this was not observed in female patients with RAS wt tumors. Clinical trial information: NCT01249638.

Gender and survival benefit from initial irinotecan in metastatic colorectal cancer: Analysis of the XELAVIRI (AIOKRK0110) study.

549 Background: XELAVIRI compared initial versus sequential irinotecan (iri) in combination with fluoropyrimidine (FP) plus bevacizumab (bev) in patients (pts) with mCRC, trial identification: NCT01249638. In the full analysis set of the study, non inferiority of time to failure of strategy (TFS) of the sequential use could not be demonstrated (primary endpoint). Methods: The secondary endpoints overall response rate (ORR), progression-free survival (PFS) as well as overall survival (OS) were evaluated in female versus male pts as well as molecular subgroups (RAS mutational status). Interaction of treatment and gender was tested by likelihood ratio tests. Results: Of 421 patients, 281/140 were male/female. In female pts, ORR was 43% in both arms, PFS was 8.9 (95% CI 6.8-11.1) versus 10.1 (95% CI 8.5-11.8) months (HR: 1.09 (95% CI 0.76-1.55), P = 0.65) in pts with initial iri versus pts without initial iri, respectively. In females, a trend for inferior OS with initial iri was seen: 21.8 (95% CI 14.8-28.8) months with initial iri versus 28.4 (95% CI 21.9-34.9) months without initial iri (HR: 1.46 (95% CI 0.95-2.24), P = 0.08). This difference was significant in the multivariate analysis (HR: 1.73 (95% CI 1.04-2.86, P = 0.034). Male pts benefitted across all analysed endpoints from initial iri: ORR was 58.3% with initial iri and 33.6% without iri (P &lt; 0.001), PFS was 10.1 (95% CI 9.2-11.0) versus 7.4 (95% CI 6.3-8.5) months (HR: 0.54 (95% CI 0.42-0.69) P &lt; 0.001) and OS 23.9 (95% CI 19.1- 28.6) versus 20.5 (95% CI 18.1-22.9) months (HR: 0.63 (95% CI 0.47-0.85), P = 0.002), with initial iri versus without initial iri, respectively. Interaction of treatment and gender was seen for ORR (P = 0.018), PFS (P = 0.002) and OS (P = 0.001). Additional data including treatment and toxicities will be presented at the meeting. Conclusions: This unplanned exploratory analysis suggests that gender might interact with efficacy of initial iri when used in the context of FP and bev. While male patients derived a significant and clinically meaningful benefit from initial use of iri, this was not observed in female patients. Clinical trial information: NCT01249638.

Multi factor Authentication Model using Fingerprint Hash code and Iris Recognition

Authentication is using one or multiple mechanisms to show that you are who you claim to be. As soon as the identity of the human or machine is demonstrated, then human or machine is authorized to grant some services. The modern research study reveals that fingerprint is not so secured like secured a password which consists of alphanumeric characters, number and special characters. This model proposes instead of password iris of the user, which is also one of the strongest physiological biometrics recognition systems. The iris is absolutely fashioned by way of eighth month of adults, and remains stable throughout the life span. In recent years, the usage of Iris for human identification has substantially grown due to the tremendous advantages with traditional or usual or normal authentication techniques based on private identity numbers (PINs) or passwords. In fact, given that iris is intrinsically and uniquely related to a character, they can't be forgotten, without difficulty stolen or reproduced. But, the use of Iris may additionally have some drawbacks related to viable safety breaches. On the grounds that iris traits are limited and immutable, if an attacker has gets access to the database where they are saved, the system security may be irreparably compromised. To deal with this hassle, an iris structure with template protection becomes very much essential. In this paper the different methods of iris recognition are studied with its features. This paper also discusses about multifactor authentication model.

Multifactor Authentication Model using Fingerprint Hash code and Iris Recognition

Authentication is using one or multiple mechanisms to show that you are who you claim to be. As soon as the identity of the human or machine is demonstrated, then human or machine is authorized to grant some services. The modern research study reveals that fingerprint is not so secured like secured a password which consists of alphanumeric characters, number and special characters. This model proposes instead of password iris of the user, which is also one of the strongest physiological biometrics recognition systems. The iris is absolutely fashioned by way of eighth month of adults, and remains stable throughout the life span. In recent years, the usage of Iris for human identification has substantially grown due to the tremendous advantages with traditional or usual or normal authentication techniques based on private identity numbers (PINs) or passwords. In fact, given that iris is intrinsically and uniquely related to a character, they can't be forgotten, without difficulty stolen or reproduced. But, the use of Iris may additionally have some drawbacks related to viable safety breaches. On the grounds that iris traits are limited and immutable, if an attacker has gets access to the database where they are saved, the system security may be irreparably compromised. To deal with this hassle, an iris structure with template protection becomes very much essential. In this paper the different methods of iris recognition are studied with its features. This paper also discusses about multifactor authentication model.

Contact lens detection for iris spoofing countermeasure

The development of biometric authentication system should be followed by strengthening to spoofing attempts. Among various identifiers, iris has aroused many attentions due to its uniqueness and stability. Nevertheless, the use of iris for biometric authentication is accompanied by spoofing risk, for example using contact lens. In order to handle the spoofing attempts, its detection is an inevitable part of a recognition system, to reduce the risk of forging system. Cosmetic contact lens is one of most common spoofing materials which is hard to be detected. In this study, weighted local binary pattern (w-LBP) and simplified scale invariant feature transform (SIFT) descriptors were used to extract the feature of the iris, in which segmented using gradient magnitude and Fourier descriptor. Simplified SIFT descriptor is extracted at each pixel of iris image and being used to rank the local binary pattern (LBP) sequence of encoding. The features were then presented to support vector machine (SVM) classifier, for positive vs. negative classification. Positive class means that contact lens was used by a person, and vice versa. The experimental results showed that combining SIFT and w-LBP as features for SVM yielded an accuracy of 84%.

Real-time image-guided nasogastric feeding tube placement: A case series using Kangaroo with IRIS Technology in an ICU

ObjectivePulmonary misplacement during the blind insertion of enteral feeding tubes is frequent, particularly in ventilated and neurologically impaired patients. This is probably the first clinical study using the Kangaroo Feeding Tube with IRIS technology (IRIS) which incorporates a camera designed to provide anatomic landmark visualization during insertion. The study aim was to evaluate IRIS performance during bedside gastric placement. MethodsThis is the first prospective study to collect data on the use of IRIS. Twenty consecutive unconscious patients requiring enteral nutrition were recruited at a single center. IRIS placement was considered complete when a clear image of the gastric mucosa appeared. Correct placement was confirmed using a contrast-enhanced abdominal X-ray. To evaluate the device performance over time, the camera was activated every other day up to 17 d postplacement. ResultsIn 7 (35%) patients, the trachea was initially visualized, requiring a second placement attempt with the same tube. The IRIS camera allowed recognition of the gastric mucosa in 18 (90%) patients. The esophagogastric junction was identified in one patient, while in a second patient the quality of visualization was poor. Contrast-enhanced X-ray confirmed the gastric placement of IRIS in all patients. IRIS allowed identification of gastric mucosa in 14 (70%) patients 3 d after placement. Performance progressively declined with time (P = 0.006, chi-square for trend). ConclusionIRIS placement could have spared X-ray confirmation in almost all patients and prevented misplacement into the airway in about one third. Visualization quality needs to be improved, particularly after the first week.

Chemotherapy (Ctx) use and adoption of new agents in older versus younger patients (pts) with metastatic colorectal cancer (mCRC).

674 Background: The treatment of mCRC has changed substantially in the last 2 decades but adoption of new drugs has not been well studied in older pts. We explored the effect of age and comorbidities on the adoption of irinotecan (Iri) and oxaliplatin (Ox) in mCRC pts over a 15 year timespan. Methods: mCRC pts receiving 5-Fluorouracil (5FU) based Ctx between 1995-2009 were studied using the LifeLink Health Plan Claims Database, and evaluated based on age (&gt;70 vs ≤70y). Pts were identified by ICD-9 / HCPCS (J) codes. The fraction of pts receiving Ctx was calculated at yearly intervals and any other agent received with 5FU defined combination Ctx. Charlson Comorbidity Index (CCI) was used to assess comorbidity burden. Wilcoxon's and χ2test were used in univariate and logistic regression in multivariate analyses (MVA). Results: 16087 pts were identified with a median age of 61y and 55% males. The difference in proportions of older vs younger pts receiving Ctx for mCRC remained stable over the 15 year period. There was an increase in the fraction of pts with CCI&gt;1 over time (14% in 1996; 40% after 2004 (p&lt;0.05). Older pts had higher rate of CCI&gt;1 (Table). Use of single agent 5FU declined in both groups over time. After FDA approval, use of Iri was lower in older pts (15 vs 38% in 1998, p&lt;0.05), but this difference resolved by 2002 (62% both groups, p=0.9). Similarly, Ox was used more frequently in younger pts after initial approval (15% vs 22% in 2003), with decrease in this difference by 2009 (60% vs 64%,p=0.9). Older pts were less likely to get &gt;2 agents when compared to younger (15 vs 22%, 29 vs 39% and 11 vs 16% in 2003, 2006 &amp; 2009 respectively, p&lt;0.001). On MVA, likelihood of receiving combination Ctx increased over time [OR 1.2; 1.18-1.26; p&lt;0.01], but was lower in older pts [OR 0.65;0.59-0.71, p&lt;0.001] and pts with CCI&gt;1 [OR 0.84;0.77-0.91; p&lt;0.001]. Conclusions: In a group of commercially insured pts, a lower fraction of older pts are treated for mCRC and adoption of new agents into the treatment of older pts appears to lag behind that of younger pts. However, oncologists have become more comfortable treating older pts with comorbidities over time. [Table: see text]

664TiP - A Phase I Trial of Irinotecan (IRI) and BKM120 in Previously Treated Patients (PTS) With Metastic Colorectal Cancer (MCRC)

ABSTRACT Background Reversal of Iri resistance may result with use of Iri plus anti-EGFR antibody in pts with kras wild-type mCRC. BKM120 is an oral pan-class PI3K inhibitor. The published results of a phase I trial of single agent BKM120 showed that BKM120 was well-tolerated and safe with favorable PK profile and promising anti-tumor effect. Methods The primary objective of this phase I trial is to identify the maximum tolerated dose (MTD) for Iri and BKM120 combination in previously treated mCRC. The secondary objectives are to characterize the PK of Iri with or without BKM120 as well as PK of BKM120 when administered with Iri, to determine clinical response to the combination, and to correlate the expression of biomarkers associated with PI3K signaling pathway with clinical response to the combination of Iri plus BKM120. A traditional 3 + 3 dosing scheme is used for dose escalation. Iri is given intravenously every 14 days and BKM daily. Iri starts on cycle 1 day 1 while BKM120 starts after 24 hours after the first dose of Iri to allow us to monitor the PK of Iri both in the absence and presence of BKM120. The patients are assessed for safety and toxicities every cycle (q14 days). Results Eleven pts have been enrolled: six were evaluable for toxicity: 3 in cohort 0 (Iri 120 mg/m2 + BKM120 50 mg/d) and 3 in cohort 1 (Iri 150 mg/m2 + BKM 120 50 mg/d). The most common drug related adverse events were nausea and vomiting, diarrhea, fatigue, hyperglycemia, and elevation of transaminases. One dose limiting toxicity (DLT), genital mucositis, was observed in a male pt in Cohort 1. This resolved in less than 7 days but pt missed more than 7 days of BKM120. The MTD has not been reached. Of the 4 pts who have completed 4 cycles of therapy 3 had stable disease and one had progressive disease. The cycle 1 vs cycle 2 PK for cohort 0 showed SN-38 mean Cmax2/Cmax1 was 0.89 + 0.16 and mean AUC2/AUC1 1.07 + 0.16. The Iri PKs for subsequent cohorts and BKM120 PKs as well as the molecular correlates will be presented. Conclusion This is the first human trial of the combination of Iri and BKM120. No significant toxicities have been observed and the PK of Iri does not seem to be affected by BKM120. These preliminary data support continuing the effort to find the MTD for the combination of Iri and BKM120 for use in phase II trials and to identify potential biomarkers of response and toxicities. Disclosure J.C. Baranda: Research Funds: Novartis, Roche. K. Bhalla: Novartis, Research Funding Novartis, honorarium, advisor. All other authors have declared no conflicts of interest.

Evaluation of vocal acoustic and efficiency analysis parameters in medical students and academic teachers with use of iris and diagnoscope specialist software

The aim of this study was to compare the parameters of vocal acoustic and vocal efficiency analyses in medical students and academic teachers with use of the IRIS and DiagnoScope Specialist software and to evaluate their usefulness in prevention and certification of occupational disease. The study group comprised 40 women, including students and employees of the Military Medical Faculty, Medical University of Łodź. After informed consent had been obtained from the participant women, the primary medical history was taken, videolaryngoscopic and stroboscopic examinations were performed and diagnostic vocal acoustic analysis was carried out with the use of the IRIS and Diagno-Scope Specialist software. Based on the results of the performed measurements, the statistical analysis evidenced the compatibility between two software programs, IRIS and DiagnoScope Specialist, with the only exception of the F4 formant. The mean values of vocal acoustic parameters in medical students and academic teachers, obtained by means of the IRIS software, can be used as standards for the female population not yet developed by the producer. When using the DiagnoScope Specialist software, some mean values were higher and some lower than the standards specified by the producer. The study evidenced the compatibility between two measurement software programs, IRIS and DiagnoScope Specialist, except for the F4 formant. It should be noted that the later has advantage over the former since the standard values of vocal acoustic parameters have been worked out by the producer. Moreover, they only slightly departed from the values obtained in our study and may be useful in diagnostics of occupational voice disorders.

Assessing the performance of biogas plants with multi-criteria and data envelopment analysis

This paper performs an assessment of 41 agricultural biogas plants located in Austria to determine their relative performance in terms of economic, environmental, and social criteria and corresponding indicators. The comparison of these renewable energy conversion plants is based on two complementary analyses. Data envelopment analysis (DEA) was conducted to provide measures of radial efficiency relative to the observed frontier of production possibilities. Multi-criteria decision analysis (MCDA), using the IRIS/ELECTRE TRI methodology, was conducted to obtain a different perspective on the results, and as a tool that would enable to incorporate managerial preferences easily. To be able to use IRIS while keeping the spirit behind DEA, the evaluation criteria were defined as different output/input efficiency ratios, and no information about criteria weights was introduced at the outset. The results suggest that MCDA, and the use of IRIS in particular, constitutes a useful approach that can be applied in a complementary way to DEA.

Use of IRI to model the effect of ionosphere emission on earth remote sensing at L-band

Microwave remote sensing in the window at 1.413 GHz (L-band) set aside for passive use only is important for monitoring sea surface salinity and soil moisture. These parameters are important for understanding ocean dynamics and energy exchange between the surface and atmosphere, and both NASA and ESA plan to launch satellite sensors to monitor these parameters at L-band (Aquarius, Hydros and SMOS). The ionosphere is an important source of error for passive remote sensing at this frequency. In addition to Faraday rotation, emission from the ionosphere is also a potential source of error at L-band. As an aid for correcting for emission, a regression model is presented that relates ionosphere emission to the total electron density (TEC). The goal is to use TEC from sources such as TOPEX, JASON or GPS to obtain estimates of emission over the oceans where the electron density profiles needed to compute emission are not available. In addition, data will also be presented to evaluate the use of the IRI for computing emission over the ocean.

Pseudophakic cystoid macular edema

Cystoid macular edema (CME) following cataract surgery has been recognized for over 50 years as an important cause of suboptimal post-operative vision. The incidence of CME varies widely, but is likely in the range of 1-2% using modern cataract extraction techniques. The diagnosis of CME can generally be made on clinical examination with evidence of perifoveal cystic spaces and can be confirmed with use of fluorescein angiography to document the classic petaloid pattern of leakage mainly into the outer retina. Leak from perifoveal vessels is induced by inflammatory mediators and results in intraretinal fluid accumulation and corresponding decrease in retinal function. The risk factors most associated with CME; rupture of posterior capsule, vitreous loss, iris incarceration, use of iris fixated lenses, active uveitis and diabetes, may all increase the potency of these mediators and exacerbate post-operative CME. The treatment of CME remains controversial but generally starts with conservative observation in isolated angiographic cases and progresses through topical non-steroidal anti-inflammatory agents (NSAIDs), topical steroids, peri-ocular steroids, systemic steroids and surgical intervention in refractory cases. Even more controversial is the role of NSAID prophylaxis peri-operatively in preventing clinical CME. Though the data is tantalizing in the short term, there is little to support the long-term benefit of such prophylaxis with respect to visual outcomes.

Methods of studying fish feeding: reply

Dietary descriptions of fish and other aquatic vertebrates are greatly influenced by the choice of the method used to quantify the relative importance or contribution of each prey type to the diet. This is because the most commonly used measures (numerical abundance, frequency of occurrence, and volume or weight measures) convey different types of information on feeding habits (Macdonald and Green 1983; Bigg and Perez 1985; Cortes 1997). This limitation of single indices led Pinkas et al. (1971) to propose the index of relative importance, or IRI, a compound index that describes the relative contribution of stomach contents to the diet. In a recent paper (Cortes 1997), I proposed to include the IRI standardized to 100% (%IRI), in addition to reporting the three single measures, to facilitate comparisons between dietary studies. Hansson argues that the IRI should be abandoned overall because it underrepresents lower taxonomic categories as shown in a hypothetical example. Some of the limitations and biases of the single measures and some compound indices have been discussed elsewhere (Pinkas et al. 1971; Hyslop 1980; Macdonald and Green 1983; Bigg and Perez 1985). I argued that all three single measures should be reported when attempting to describe diets of populations or species because use of only one or two of them can be misleading (Fig. 2b in Cortes 1997 illustrates this point). Ideally, energy value of the prey should also be included as a measure of dietary importance, but this is beyond the scope of most studies. In his comment, Hansson shows that the IRI has limitations when attempting to quantify stomach contents from a single study because of the multiplicative effect that %O has on the index, with the net result of underestimating the contribution of those prey species identified to a lower taxonomic level. Although this is a valid point, I contend that the value of %O used in his example greatly influences the outcome, as recognized by Hansson. Before completely ruling out the use of IRI in dietary studies, its suitability and, by extension, that of all compound indices should be investigated further with examples drawn from multiple real data sets. As also pointed out by Hansson, conclusions should be based on numerical or statistical analyses, rather than on personal preferences or limited testing of hypothetical examples. My recommendation of using %IRI responded more to a need to promote consistency and facilitate comparisons (Cortes 1997) than to a strong advocacy for compound indices. Indeed, I proposed to depict all three single measures graphically to easily visualize the importance of each food category in stomach content analyses. However, when making intraor inter-specific comparisons, such as in calculations of dietary overlap, dietary breadth, or trophic levels, use of %IRI as a standardized measure can be useful despite the bias associated with this measure. In my opinion, it is preferable to using a single index because %IRI is an individual metric that integrates all three single measures, each of which can lead to misleading interpretations when used separately. For example, use of %N only to describe the diet of the blue shark would give the false impression that crustaceans are by far the most important item (Fig. 2b in Cortes 1997). In contrast, %IRI also considers contributions in weight and occurrence, thus emphasizing more the importance of cephalopodian molluscs and teleost fishes in the diet, which is more accurate (as determined in numerous studies of blue shark diets). Furthermore, if another study of blue shark diet were to use only %O or %W, for example, comparisons would be hindered because %N and %O or %W are not directly comparable. By combining the three single indices, %IRI puts results into a common metric, more amenable for use in diet comparisons and calculation of other trophic measures.

Longitudinal and transverse impedance of an iris in a beam pipe.

The use of iris loaded cavities to accelerate high current bunched beams makes it important to understand the impedance and wake fields caused by an iris in a beam pipe. In this paper we present a method to calculate both the longitudinal and transverse impedance of a circular iris of radius b and thickness g in a circular beam pipe of radius a for ultrarelativistic particles. An integral equation is derived for the transverse electric field at the junction between the iris and the beam pipe and a variational expression is obtained for the impedance, using the transverse field as a trial function. Accurate numerical results are obtained for the longitudinal and transverse impedances using a trial function with only a few adjustable parameters. By invoking causality we confirm the analytic behavior of the impedances in the complex frequency plane and obtain the corresponding wake functions. We particularly explore the limit b\ensuremath{\rightarrow}\ensuremath{\infty} to compare with previous studies of the impedance of a circular hole in a transverse metallic plane.

Broad-Band Wave-Guide Admittance Matching by Use of Irises

A procedure is described for broad-band admittance matching of wave-guide devices by the use of simple irises. Slotted-line measurements yield the standing-wave ratio and position of voltage minimum for several wavelengths and allow the determination of the transverse plane along the axis of the wave guide at which the dispersion with wavelength of the reflection-coefficient phase is a minimum. For regions in which the standing-wave ratio is approximately independent of wavelength, this information determines the optimum position and dimensions of a purely susceptive iris which matches the admittance of the load to that of the wave guide.