Error Of Plus Research Articles

Monitoring and management of hypertriglyceridemia in extremely low birth weight neonates receiving intravenous lipid emulsions: A national survey

AimTo assess the practice variation of defining, monitoring and managing hypertriglyceridemia (HTG) in extremely low birth weight neonates receiving intravenous lipid emulsions (IVLE). MethodsAn 8-question survey created via the web survey site Qualtrics was distributed to neonatologists, neonatal nurse practitioners and fellows within the Section of Neonatal-Perinatal Medicine email directory list in the United States and Canada. Survey results were obtained between August and September 2022. ResultsThere were 249 respondents from approximately 4000 members within the Section of Neonatal-Perinatal Medicine. Responses were documented as a frequency (percentage) with a margin of error of plus or minus 6.2 %. Most respondents were neonatologists, individuals practicing for >10 years and reported a unit-based policy for IVLE initiation and advancement. The definitions of HTG varied among respondents, with the majority (42.7 %) reporting a defining threshold of >200 mg/dL. Nineteen percent of respondents reported not routinely monitoring serum triglyceride concentrations with variable triglyceride monitoring intervals reported by other survey respondents. Regarding elevated triglyceride concentrations, 19.0 % reported decreasing the IVLE rate and checking triglyceride concentrations until normalization; 14.6 % reported IVLE discontinuation and monitoring triglyceride concentrations until normalization; 61.9 % reported using a combination of the above practices; and 4.4 % reported individualized practices for IVLE management with elevated triglyceride concentrations. ConclusionThis survey demonstrates a high variation in defining, monitoring and managing HTG in extremely low birth weight neonates and emphasizes the need for studies to better guide this practice.

Novel thoracoscopic segmentectomy combining preoperative three-dimensional image simulation and intravenous administration of indocyanine green

OBJECTIVESThe aim of this study is to assess prospectively the validity and feasibility of segmentectomy using preoperative simulation and intravenous indocyanine green (ICG) with near-infrared (NIR) light thoracoscope to ensure a sufficient surgical margin.METHODSThis study was a prospective, single-centre, phase II, feasibility study. From February to July 2021, 20 patients were enrolled in this study. All patients underwent preoperative three-dimensional computed tomography angiography and bronchography using simulation software. The dominant pulmonary artery of the targeted segment was selected to determine the dissection line and measure the surgical margin to the tumour. Intraoperatively, after the planned dissection of the pulmonary artery, ICG (0.3 mg/kg) was administered intravenously and observed with NIR, and dissection was performed along the line determined by preoperative simulation. Postoperatively, the pathological margin was compared with the simulation margin.RESULTSAll surgeries were performed via an uniport (3.5–4.0-cm skin incision). The regions of segmentectomy were S2, S3, S6, S9 + 10 and S10 of the right side and S1 + 2 + 3, S3, S3 + 4 + 5, S6 and S8 of the left side. The difference between the simulation margin and the pathological margin was not significant (simulation 30.5 ± 10.1 vs pathological 31.0 ± 11.0 mm, P = 0.801). The simulation margin was well correlated with the pathological margin (R2 = 0.677). The proportion of cases successfully achieving the pathological margin of error of plus or minus 10 mm of the simulation margin was 90% (18 of 20 cases).CONCLUSIONSThe combination of preoperative three-dimensional computed tomography simulation and ICG–NIR was effective for securing a sufficient margin in segmentectomy.

Position-based routing protocol using Kalman filter as a prediction module for vehicular ad hoc networks

A vehicle’s Global Positioning System (GPS) location is used as the Location_ID in position-based routing protocols. The accuracy of GPS is a major concern in vehicular ad hoc networks (VANETs), as it is influenced by environmental and technical factors. Therefore, a vehicle’s actual location is different from its GPS location, with a margin of error of plus or minus 5–100 m. To reduce the effect of the margin of error on routing, this study evaluated the position-based routing protocol by using the Kalman filter (KF) and extended Kalman filter (EKF). Each of these was utilized individually as a prediction module for the purpose of improving the average delay (AD), packet delivery ratio (PDR), and throughput by minimizing location error. The KF and EKF prediction modules were implemented using C++ programming and the Eigen library, which were further incorporated into an NS-3.23 simulator. The proposed routing protocol performance was compared with cross-layer, weighted, and position-based routing (CLWPR) protocol in terms of PDR, AD, and throughput.

New Measurement Method of Broadband Permittivity and Permeability of Non-Solid Materials in Small Quantity

Evaluation of permittivity (e) and permeability (μ) of magnetic/dielectric material in microwave band becomes more important with the rapid expansion of microwave technologies. Transmission/reflection line method is well known as a simultaneous measurement method of e and μ in the band. However in this method material under test (MUT) is limited to solid state. On the other hand, for measuring liquid material open ended coaxial probe method was proposed. The method is disadvantageous in terms of requiring deciliter volumes of MUT for approximating a semi-space filled by MUT. We propose a new measurement method with the aim of simultaneous measuring both of permittivity and permeability of not only solid material but also a small amount of liquid, powder, and gel state material. A plastic toroidal case was utilized to encapsulate non-solid state MUT and whole the case was evaluated by coaxial line method. In this study the cases were modeled using Acrylic 3-D printer (Stratasys, Objet 260 Connex). An example of the plastic case with a cap fabricated is shown in Fig. 1. Outer and inner diameter (7.00 and 3.00 mm) of the case was designed to fit to a coaxial sample holder (KEAD Inc., CSH2-APC7). The length of the case including a cap thickness measured by digital vernier caliper was 5.00 mm. In the same way, thickness of wall, bottom, and cap was 0.45, 0.50, and 0.50 mm, respectively. Accordingly the volume of MUT required for the case was about 70 microliters. The specimen which MUT was encapsulated was inserted to the coaxial sample holder and complex scattering (S) parameters from 1–10 GHz were taken using a vector network analyzer (Hewlett-Packard, HP 8720D). S-parameters whose reference planes were both upper and lower surface of the specimen were obtained by shifting reference planes of the measured S-parameters. After that we obtained S-parameters of MUT in numerical calculations mentioned below in order to take away unwanted plastic case portions. The specimen can be divided into three coaxial portions: Inner cylindrical wall, outer cylindrical wall, and middle core including MUT between their walls. From the viewpoint of electric circuit it corresponds to a series connection of the three two-port networks. Impedance (Z) parameters of the middle core were obtained using the relationship: Z-matrix of the specimen equals to the sum of their three Z-matrices. Z-matrix of the specimen was obtained by converting S-matrix of it by a reference impedance. Z-matrix of outer and inner wall was obtained from e and μ measured in advance using solid specimens of the plastic material and outer and inner diameters of their cylindrical walls. Z-matrix of the middle core was converted S-matrix again. The middle slender core can be divided into three coaxial portions: a part of cap, a part of bottom, and MUT. The core corresponds to a cascaded connection of the three two-port networks. Transfer (T) parameters of MUT were obtained using the relationship: T-matrix of the core equals to the product of their three T-matrices. T-matrix of the core was obtained by converting S-matrix of it. T-matrix of a part of bottom and cap was obtained from e and μ of the plastic material used and bottom and cap thickness. Finally e and μ of MUT were calculated from S-parameters of it using Nicolson-Ross-Wier algorithm [1, 2]. In this study, the air at the volume was measured as MUT in order to confirm a validity of the proposed method. The dependences of real and imaginary part of relative permittivity of air obtained by this method on frequency were shown in Fig. 2(a) and Fig. 2(b). Although the both values had a margin of error of plus or minus 10% a constant and nearly ideal relative permittivity of air was confirmed in the band measured from these figures. This result indicates that the proposed method is effective for measuring non-solid materials.

A chaos-oriented prediction and suppression model to enhance the security for cyber physical power systems

Smart grid has become a fully automated system with common use of electronic equipments to control, compute and communicate. This can be modeled as cyber physical power systems (CPPS) to analyze connections and interactions, and security is one of the key factors to find the inner unmanaged vulnerabilities. In some cases, voltage source inverters (VSI) with pulse width modulation (PWM) are sensitive to initial conditions, and this is a typical chaotic state. In this paper, we present a CPPS model with the improved chaos prediction and suppression methods to enhance the security with the abilities to avoid and eliminate chaos. The main process is “prediction–quantization–control”. First, an improved maximum velocity criterion method is used to predict the possibility of chaos in the parameter space of CPPS. Second, when a possibility of chaos is predicted, a sinusoidal wave frequency modulation is used to suppress chaos. To analyze the connections of the inner entities’ transmission, a security coefficient is introduced to obtain hazard perception and to express measurements quantitatively. Third, it has proposed a chaotic control algorithm based on a fuzzy model with closed-loop dynamic mechanism to solve the security coefficient effectively. The experiments prove the predicted result has a margin of error of plus or minus 10%, and the sinusoidal wave frequency modulation can avoid chaos on CPPS. Also, the results show that security coefficient increases by 13.89%, which means it is useful with sensitive parameters and other related disturbances. Overall, this CPPS model can eliminate potential chaos phenomena caused by inversion processes, and it can be used into smart grids to improve the security effectively.

Influence of a roughness length error on vertical wind speed extrapolation for 2D ideal hills using an OpenFOAM®RANS simulation

In modelling wind flow over a flat and complex terrain, the choice of roughness- length-distribution is critical for accurate wind speed predications. This choice is often made based on the Davenport scale (1). A satellite or aerial image of the location is used (2-4) and subjective or objective measures are used for translating the image into roughness length - z0 - based on the Davenport scale. The choice of a Davenport table value is generally regarded as within an error of plus or minus one table value, leading to a ±6% error in wind speed predictions for a flat terrain in neutral conditions (5). In the paper this error is studied for a non-flat terrain, using a series of CFD simulations for 2D hills of various combinations of aspect ratio and steepness. Results show that the wind speed prediction error as a result of a wrong parameterization decreases with hill steepness until separation occurs. As a result of separation the error increases slightly, and then decreases again with a further increase in hill steepness.

A numerical study on the impact of tidal waves on the storm surge in the north of Liaodong Bay

A storm surge is an abnormal sharp rise or fall in the seawater level produced by the strong wind and low pressure field of an approaching storm system. A storm tide is a water level rise or fall caused by the combined effect of the storm surge and an astronomical tide. The storm surge depends on many factors, such as the tracks of typhoon movement, the intensity of typhoon, the topography of sea area, the amplitude of tidal wave, the period during which the storm surge couples with the tidal wave. When coupling with different parts of a tidal wave, the storm surges caused by a typhoon vary widely. The variation of the storm surges is studied. An once-in-a-century storm surge was caused by Typhoon 7203 at Huludao Port in the north of the Liaodong Bay from July 26th to 27th, 1972. The maximum storm surge is about 1.90 m. The wind field and pressure field used in numerical simulations in the research were derived from the historical data of the Typhoon 7203 from July 23rd to 28th, 1972. DHI Mike21 is used as the software tools. The whole Bohai Sea is defined as the computational domain. The numerical simulation models are forced with sea levels at water boundaries, that is the tide along the Bohai Straits from July 18th to 29th (2012). The tide wave and the storm tides caused by the wind field and pressure field mentioned above are calculated in the numerical simulations. The coupling processes of storm surges and tidal waves are simulated in the following way. The first simulation start date and time are 00:00 July 18th, 2012; the second simulation start date and time are 03:00 July 18th, 2012. There is a three-hour lag between the start date and time of the simulation and that of the former one, the last simulation start date and time are 00:00 July 25th, 2012. All the simulations have a same duration of 5 days, which is same as the time length of typhoon data. With the first day and the second day simulation output, which is affected by the initial field, being ignored, only the 3rd to 5th day simulation results are used to study the rules of the storm surges in the north of the Liaodong Bay. In total, 57 cases are calculated and analyzed, including the coupling effects between the storm surge and a tidal wave during different tidal durations and on different tidal levels. Based on the results of the 57 numerical examples, the following conclusions are obtained: For the same location, the maximum storm surges are determined by the primary vibration (the storm tide keeps rising quickly) duration and tidal duration. If the primary vibration duration is a part of the flood tidal duration, the maximum storm surge is lower (1.01, 1.05 and 1.37m at the Huludao Port, the Daling Estuary and the Liaohe Estuary respectively). If the primary vibration duration is a part of the ebb tidal duration, the maximum storm surge is higher (1.92, 2.05 and 2.80 m at the Huludao Port, the Daling Estuary and the Liaohe Estuary respectively). In the mean time, the sea level restrains the growth of storm surges. The hour of the highest storm tide has a margin of error of plus or minus 80 min, comparing the high water hour of the astronomical tide, in the north of the Liaodong Bay.

He I VECTOR MAGNETOMETRY OF FIELD-ALIGNED SUPERPENUMBRAL FIBRILS

Atomic-level polarization and Zeeman effect diagnostics in the neutral helium triplet at 10830 angstroms in principle allow full vector magnetometry of fine-scaled chromospheric fibrils. We present high-resolution spectropolarimetric observations of superpenumbral fibrils in the He I triplet with sufficient polarimetric sensitivity to infer their full magnetic field geometry. He I observations from the Facility Infrared Spectropolarimeter (FIRS) are paired with high-resolution observations of the Halpha 6563 angstroms and Ca II 8542 angstroms spectral lines from the Interferometric Bidimensional Spectrometer (IBIS) from the Dunn Solar Telescope in New Mexico. Linear and circular polarization signatures in the He I triplet are measured and described, as well as analyzed with the advanced inversion capability of the "Hanle and Zeeman Light" (HAZEL) modeling code. Our analysis provides direct evidence for the often assumed field alignment of fibril structures. The projected angle of the fibrils and the inferred magnetic field geometry align within an error of plus or minus 10 degrees. We describe changes in the inclination angle of these features that reflect their connectivity with the photospheric magnetic field. Evidence for an accelerated flow (approx 40 m/s^2) along an individual fibril anchored at its endpoints in the strong sunspot and weaker plage in part supports the magnetic siphon-flow mechanism's role in the inverse Evershed effect. However, the connectivity of the outer endpoint of many of the fibrils cannot be established.

Postprandial performance of Dexcom® SEVEN® PLUS and Medtronic® Paradigm® Veo™: Modeling and statistical analysis

BackgroundMinimizing excessive postprandial glucose excursion is still an unmet need in treating diabetes. This work addresses the analysis and modeling in the postprandial state of two commercial CGM devices. MethodsTwelve patients with type 1 diabetes were studied in the postprandial state on four different occasions under controlled conditions. Each time, we performed simultaneous glucose monitoring using the Dexcom SEVEN® PLUS (47 datasets) and the Medtronic Paradigm® Veo™ (42 datasets). The following statistical properties of the error signal were analyzed and modeled sequentially for the two devices: the lag time, the error stationarity, the error probability distribution and the time correlation. Finally, models were built for sensor simulation in silico studies. ResultsLag time followed an exponential probability distribution for both monitors (μsevenplus=108, μveo=1.69). Standard deviation and mean of the error signal, calculated as time-dependent signals across the population of sensors, were time-varying and correlated with the reference value and its rate of change, respectively. In both cases, a high variability of postprandial behaviors was observed. After non-stationarity compensation, a logistic distribution was obtained for the SEVEN® PLUS error (close to normal distribution). Regarding the Paradigm® Veo™, a multimodal distribution was obtained, which turned into normal after elimination of five “unstable” sensors. Finally, a first order autoregressive model fitted the SEVEN® PLUS error time-series while a third-order filter was necessary for the Paradigm® Veo™. ConclusionsThe Paradigm® Veo™ device exhibited greater delay variability with higher delay time and higher probability of abnormal sensor behaviors as compared to the SEVEN® PLUS device. In both cases, the observed variability may have important clinical implications in postprandial performance. Therefore, further improvements are needed in calibration algorithms to reduce this variability.

Polled Elderly: Seven Key Primary Care Services Missed

In a poll of senior citizens, a majority reported that their physicians were not offering recommended evidence-based services such as asking about recent falls or seeking to verify medications being taken. The poll of 1,028 Americans aged 65 years and older, conducted by Lake Research Partners for the John A. Hartford Foundation, took place in late February and early March and has a margin of error of plus or minus 3.1 percentage points. Among other questions, the respondents were asked if their physicians had offered seven basic services that are typical of good geriatric care, Chris Langston, Ph.D., a program director at the foundation, said. The vast majority of those surveyed – 93% – said that they saw their primary care physician regularly. Among the respondents, 82% had one to nine physician visits annually, with half reporting three to nine visits per year. Ninety-six percent said they were completely or somewhat satisfied with their care. And yet only 7% of respondents said they had received all seven services generally considered to be good care. Just over half had received none or only one. In addition to fall risk and medications, seniors were asked whether their physicians addressed how to avoid falling, screened them for depression, provided referrals to community-based health resources, discussed their ability to perform routine daily activities such as shopping, and determined whether they needed help with personal tasks such as showering. The results are “extremely interesting and confirmatory of other work looking at doctors’ actual practice,” said Dr. Rosanne Leipzig, a professor of geriatrics and palliative medicine at Mount Sinai School of Medicine, New York. Of concern, she said, was that a third of seniors surveyed said that a physician had not sat down with them to review all their medications and supplements. About a third of patients said their physicians had asked them in the last year whether they'd had a fall or if they were having any depression or other mood issue. A fifth or less said they had been asked about problems with activities of daily living or were referred to nonmedical help in the community. “Older people are not getting the care they really need that would help them live longer, more independently, and with a higher quality of life,” Dr. Langston said. Among various age cohorts, the results were not much different, even for, theoretically, more frail people over age 80, said Tresa Undem of Lake Research Partners. For instance, 75% of those over 80 said fall prevention had not been discussed in the last year. Most seniors were not aware that they were eligible for a free annual Medicare wellness visit, in which the physician discusses various aspects of care and offers many of the seven services. Seniors might be confused about the benefit, however, as Medicare shows higher uptake rates than reflected in the poll, said Ms. Undem. The poll also asked the seniors if they thought they would receive better care if physicians and nurses had more training in geriatrics. Two-thirds said yes. Most also supported a requirement for geriatrics training in nursing and medical school. Dr. Leipzig noted that it's difficult to convince physicians to go into geriatrics and that only about 300 train in the field each year. She said that other physicians should receive specialty instruction in geriatrics to counterbalance the shortage. But given the time intensity of caring for older Americans – and low reimbursement – it will be an uphill battle, she said. The typical $45 office visit fee “doesn't even come close to allowing someone to make a living,” she said. The Hartford Foundation is a private, nonprofit philanthropy.

Rendering Unto Caesar: Catholics, the State, and the Idea of a Christian Canada

The recent Canadian federal election was filled with many surprises, including the marking of a shift in traditional voting patterns among Canadian Christians. On April 23, one week before the vote, an AngusReid Survey for the Toronto Star indicated that “50 per cent of selfdescribed English-speaking Catholics outside of Quebec” would vote for the Conservative Party on 2 May 2011. The Liberals, who historically had been the party of choice for Roman Catholics, and who had boasted at least four Catholic prime ministers since 1968, would glean only twentyfive percent support from English-speaking Catholics. The NDP and Greens could count on the support of nineteen percent of Catholics and four percent respectively. While the poll only surveyed 2,269 Englishspeaking Catholic adults, it still claimed a margin of error of plus or minus 1.8 percent. These numbers aside, it appeared that Catholics within Canada were not less interested in engaging in Canadian politics and the myriad of issues at play in the public square; they were simply moving to the right and placing their trust in a prime minister who was openly an evangelical Christian and whose party, at least in some quarters, proposed a more socially conservative agenda, informed by traditional Judaeo-Christian values. Therein, in the larger national debate about “What Canada Is, or What Canada Must Represent,” this poll signals, perhaps, that one of Canada’s largest religious groups is holding firmly to a more traditional notion of Canada as a Christian country and seeking new partisan ways to achieve this vision.

Does Capital Punishment Have a Deterrent Effect? New Evidence from Postmoratorium Panel Data

Evidence on the deterrent effect of capital punishment is important for many states that are currently reconsidering their position on the issue. We examine the deterrent hypothesis by using county-level, postmoratorium panel data and a system of simultaneous equations. The procedure we employ overcomes common aggregation problems, eliminates the bias arising from unobserved heterogeneity, and provides evidence relevant for current conditions. Our results suggest that capital punishment has a strong deterrent effect; each execution results, on average, in eighteen fewer murders—with a margin of error of plus or minus ten. Tests show that results are not driven by tougher sentencing laws and are robust to many alternative specifications.

Does Capital Punishment Have a Deterrent Effect? New Evidence from Post-moratorium Panel Data

Evidence on the deterrent effect of capital punishment is important for many states that are currently reconsidering their position on the issue. We examine the deterrent hypothesis using county-level, post-moratorium panel data and a system of simultaneous equations. The procedure we employ overcomes common aggregation problems, eliminates the bias arising from unobserved heterogeneity, and provides evidence relevant for current conditions. Our results suggest that capital punishment has a strong deterrent effect; each execution results, on average, in 18 fewer murders%97with a margin of error of plus or minus 10. Tests show that results are not driven by tougher sentencing laws, and are also robust to many alternative specifications.

KITT PEAK SEEING

ABSTRACT The profiles of stellar images near the zenith are measured on 57 random nights between 1975 and 1979, by employing a sequence of Coude slit widths and an exposure meter that measures the profiles in one dimension to an average internal standard error of plus or minus 0.06 arcsec. The advantages and disadvantages of this method are discussed, together with questions of seasonal variations in seeing for Kitt Peak. The results are examined, and it is determined that directional (seeing) differences occur due to local topography or to the wind direction.

Amperometric Titration of Uranium(IV) with Cerium(IV) Utilizing the Pyrolytic Graphite Electrode.

A method was developed for the direct amperometric titration of uranium(IV). The pyrolytic graphite electrode is used as the indicator electrode and Ce(HSO/sub 4/)/sub 4/ is used as the titrant. Applied potentials of from +1.0 to 0.0 volt vs the SCE may be used, with the more positive potentials being preferred. The method has a maximum relative error of plus or minus 1.12%, over the concentration range from 0.05 to 10 mu g of U(IV) per ml. Few of the common ions interfere and the method is simple and straightforward. (auth)

Volt-ampere characteristics of a plane-parallel ionization chamber

In the study of ionization chambers filled with highpressure gases, the recombination of ions may be neglected if the study is carried out at ionization levels close to the cosmic-ray background. For engineering reasons, it is desirable to determine the volt--ampere characteristics of the chambers within a wide ionization density range. Four series of measurements were carried out at various ionization densities, varying the distance between the electrodes from 0.3 to 2.7 cm by means of Teflon sleeves. The ionization currents were measured by means of a compensationtype electrometric instrument with an error of plus or minus 1%; a dry cell battery, the tension of which could be varied from 0 to 4500 v, served as the high-voltage source. The results of measurements carried out using a distance of 0.9 cm between the electrodes confirmed that for a constant gas pressure, the relationship I = F(E) remains identical regardless of the ionization density, indicating the absence of volume recombination; in some cases initial recombination was observed. The voltage selected determines the current losses due to initial recombination of the ions and indicates the increase in the size of the chamber required for obtaining the needed sensitivity. The chambers were filledmore » with N/sub 2/ containing less than 0.01% CO/sub 2/ and 0.4% O/sub 2/.« less

Information Limitations of Radioisotope Scanning

Progressive improvements in recording methods, collimation, data extraction technics, and the selection of materials with increased differential uptake have resulted in a growing acceptance of radioisotope scanning as a useful diagnostic method. In liver scanning, for example, Bender and Blau (1) and MacIntyre et al. in our institution (8) have demonstrated lesions as small as 2 cm. In brain scanning, both Cowan (2) and the Oak Ridge National Laboratory group (6) have identified lesions differing in counting rate by only 10 per cent from the surrounding tissue. In the light of these accomplishments it is of interest to ascertain the limits of the scintillation scanning method in its present state. Two major factors, instrumentation and the clinical correlation of the scan findings, must be considered. The first of these concerns the technics of determination of the spatial distribution of radioactive material within a region of the body and the presentation of the derived information in some manner understandable to the clinician. The second factor, clinical correlation, is concerned with the relationship between anatomical configuration and the portrayal of the radioisotope distribution. It must be remembered that organ structure itself is not visualized; only the variation in radioisotope distribution is measured, and from this the anatomic configuration may only be inferred. Statistics Inherent in scanning, as in all radioisotope procedures, is the uncertainty due to the random fluctuation of counting rate. Unfortunately, radioisotope scanning is particularly sensitive to such variation because the available information is scarce. This scarcity results from the high degree of collimation used, the short period of time spent on each area, and the radiation dose limitation. To illustrate the effects of random fluctuations, the following example may be cited: A scanner moving at a speed of 10 inches per minute will traverse a 1/2-inch distance in only three seconds. A counting rate of 1,200 counts per minute will then exhibit a probable error of plus or minus 9 per cent. With such parameters, by the definition of probable error, one-half of an area of homogeneous radioactivity would exhibit a variation of plus or minus 9 per cent in counting rate with a total range of 18 per cent, while the remainder of the area would exceed these limits. Obviously, if one attempts to see displacements in the magnitude of 10 per cent, visualization cannot be realized with such large random fluctuations. Confidence in identification would not be possible until the counting rate exceeds a minimum of 5,000 c/m or 250 counts recorded over the 1/2-inch site of interest (9). The so-called accentuation technics, such as that employed in photoscanning and in the counting rate cut-off method, can greatly increase the recognition of small counting rate changes but cannot aid in the reduction of random fluctuation.

A Servo-Method for Producing Equal-Quanta, Equal-Energy, or Equal-Response Spectra*

A servo-method is described which can provide an equal-energy or equal-quanta spectrum, as well as any other type of spectral energy distribution desired for biological or physical experiments, by installation of the appropriate empirically determined cam. A grating monochromator driven by a reversing motor provides a continuous spectrum which may be scanned repeatedly at selected bandwidths, the visible range being traversed in 15 sec with a maximum error of plus or minus 3%. Also the system can be made to produce spectra which elicit responses of arbitrarily fixed magnitude from retinal preparations, equal-response spectra. The results would be in terms of deviation from an equal-energy, equal-quanta, or any other type of chosen spectrum depending on the cam employed. This servo-method has the advantage of immunity to the aging of lamps and filters and permits replacement of a defective lamp by another of the same or of an entirely different type without calibration being required. An alternative to the use of mechanical cams, intended to produce similar results employing the photoformer principle, also is described briefly.

The half life of In 116

Six independent measurements were made and the In/sup 116/ Half life was calculated by the method of least squares to give a weighted mean of 14.05 plus or minus 0.26 s. The error quoted includes a possible error of plus or minus 0.10 s from the dead-time correction uncertainty. (B.O.G.)

New Standardization Technique for X-Ray Absorption Measurements

>Tests of previously suggested methods of determining uranium in solution by x-ray absorption indicated that daily calibration of the photometer is necessary because of changes in response. It was found that by using machined aluminum plates as standards rather than uranium solutions, the time necessary for daily calibration can be reduced to about 15 minutes. The method was found to have a limit of error of plus or minus 0.25% at the 95% confidence level for a single determination of uranium in a solution equivalent to about 30 milligrams uranium dioxide per gram of solution. It was found difficult to obtain cells matched for x-ray absorption work, a point that has been insufficiently stressed in the past. (auth)