bluuebunny/crossref_metadata_2025 huggingface dataset:
Differences in leaf and root litter decomposition in tropical montane rainforests are mediated by soil microorganisms not by decomposer microarthropods
Authors: Sánchez-Galindo Laura M. , Sandmann Dorothee , Marian Franca , Lauermann Tobias , Maraun Mark , Scheu Stefan
Published: November 2022

Background

Plant litter decomposition is a key process in carbon and nutrient cycling. Among the factors determining litter decomposition rates, the role of soil biota in the decomposition of different plant litter types and its modification by variations in climatic conditions is not well understood.

Methods

In this study, we used litterbags with different mesh sizes (45 µm, 1 mm and 4 mm) to investigate the effect of microorganisms and decomposer microarthropods on leaf and root litter decomposition along an altitudinal gradient of tropical montane rainforests in Ecuador. We examined decomposition rates, litter C and N concentrations, microbial biomass and activity, as well as decomposer microarthropod abundance over one year of exposure at three different altitudes (1,000, 2,000 and 3,000 m).

Results

Leaf litter mass loss did not differ between the 1,000 and 2,000 m sites, while root litter mass loss decreased with increasing altitude. Changes in microbial biomass and activity paralleled the changes in litter decomposition rates. Access of microarthropods to litterbags only increased root litter mass loss significantly at 3,000 m. The results suggest that the impacts of climatic conditions differentially affect the decomposition of leaf and root litter, and these modifications are modulated by the quality of the local litter material. The findings also highlight litter quality as the dominant force structuring detritivore communities. Overall, the results support the view that microorganisms mostly drive decomposition processes in tropical montane rainforests with soil microarthropods playing a more important role in decomposing low-quality litter material.
Gender differences in general health and happiness: a study on Iranian engineering students
Authors: Namazi Asieh
Published: November 2022

This article aims to determine the relationship between general health and happiness in male and female engineering students in Iran. The analysis relies on a unique dataset collected through two questionnaires (Oxford Happiness and GHQ28) from a representative sample (n = 2,000). Although similar data have been collected quite independently by different communities of researchers, and empirical evidence points to very similar underlying mechanisms, but they did not consider non-normal distribution samples. In this study, data were analyzed by Kruskal–Wallis and Wilcoxon’s signed rank tests. The mean happiness and general health were 42.89 ± 14.84 and 23.76 ± 13.28, respectively. There was a positive and significant relationship between these two variables (P ≤ 0.05, r = 0.59). Happiness showed significant differences in males and females, but general health did not. In general, female students enjoyed more health and happiness. This study argues that clarifying the relationship between happiness and health in different genders can help academic authorities and youth planners to pay special attention to this issue and provide particular programs.
Correlation of 25-Hydroxy Vitamin D and Serum Lipid Profile amongst Asymptomatic Adults in Mumbai City: A Cross-sectional Study
Authors: Hinduja Anupa Resham Ashok , Asthana Ashok , Chandy David Dale , Patkar Deepak , Wankhedkar Harshad
Published: November 2022

Introduction: Deficiency of 25-Hydroxy Vitamin D (25-OH Vitamin) is prevalent globally. Vitamin D and cholesterol metabolism are known to be linked with each other. Few International studies have attempted to relate low Vitamin D level and altered serum lipid levels. However, Indian studies are lacking, hence there is a need to conduct the studies in Indian population. Aim: To study the correlation of the serum Vitamin D level with lipid profile amongst asymptomatic Indian adults in a tertiary care hospital, Mumbai, India. Materials and Methods: This cross-sectional study was conducted in SevenHills Hospital, Mumbai, Maharashtra, India (tertiary care hospital), from December 2016 to August 2017. A total of 243 asymptomatic adults, visiting the wellness clinic for routine assessment of health status were randomly selected. Study participants were divided into two groups based on Vitamin D levels. Group A (n=139) with Vitamin D level <20 ng/mL, group B (n=104) with Vitamin D ≥20 ng/mL. Group B was further segregated into sub group B1 (n=60) with Vitamin D level ≥20 ng/mL to <30 ng/mL and sub group B2 (n=44) with Vitamin D level ≥30 ng/mL. Fasting blood samples were collected to measure levels of serum Vitamin D and lipid profile. The measured values of Vitamin D and serum lipids were statistically analysed for any significant relationship using Chi-square test and Unpaired t-test and Pearson’s correlation. Results: Mean age of the participants of group A was 39.94±11.59 years and group B was 47.78±11.53 years. The difference in gender distribution and average BMI of both groups was not statistically significant (p-value=0.8599 and p-value=0.4497, respectively). On comparison of group A and group B2, average High Density Lipoprotein Cholesterol (HDL-C) level was comparatively higher amongst group B2 (52.18±11.87 mg/dL vs 45.81±12.76 mg/dL; p-value=0.0038) and average Triglyceride (TG) level was higher amongst group A (104.58±70.35 mg/dL vs 129.38±64.34 mg/dL; p-value=0.0308). There was no statistically significant linear correlation found between lipid profile parameters and Vitamin D. Conclusion: In present study, no significant correlation between Vitamin D deficiency and serum lipid profile was found. However, a statistically significant difference was found in average levels of HDL-C and TG amongst adults with adequate Vitamin D and those with Vitamin D deficiency.
Incidence of Intraoperative Hypotension and Bradycardia in Spinal Anaesthesia with 0.5% Bupivacaine alone and 0.5% Bupivacaine with Fentanyl for Abdominal Hysterectomy: A Cross-sectional Study
Authors: Sudan Swathy , Kamalakshy Remani Kelan , Raveendran Sunil , Sebastian Ranju
Published: November 2022

Introduction: Bupivacaine hydrochloride, when used for spinal anaesthesia, is associated with varying degree of hypotension and bradycardia. Intrathecal opioids provides haemodynamic stability and improves quality of perioperative analgesia. Aim: To compare the incidence of intraoperative hypotension, bradycardia and its side-effects when using 0.5% hyperbaric bupivacaine alone and with 25 µg fentanyl added to it for subarachnoid block for abdominal hysterectomy. Materials and Methods: This cross-sectional study was conducted at Government Medical College, Thrissur, Kerala, India from June 2019 to May 2020 on 96 American Society of Anaesthesiologists Physical Status (ASA-PS) I and II patients posted for total abdominal hysterectomy under lumbar subarachnoid block. They were divided into Group A and B, carrying 48 patients in each group. Group A received 3.3 mL of 0.5% hyperbaric bupivacaine alone. Group B received 3.3 mL of 0.5% hyperbaric bupivacaine and 25 µg fentanyl. Haemodynamic characteristics, analgesic properties and side-effects were compared between Group A and Group B. Data were entered in Microsoft Excel Software, and analysed using Statistical Package for the Social Sciences (SPSS) software version 16.0 and p-value <0.05 was considered as statistically significant. Results: The incidence of hypotension in group A was 41.7% and in group B was 39.6%. Incidence of analgesia was significantly higher in group B (group A - 181.2±4.9, group B - 220.9±13.9). In group A, no one had nausea and vomiting. In group B, 8.3% experienced nausea and vomiting and none in both groups experienced pruritus. Conclusion: There was no difference in the development of hypotension and bradycardia when fentanyl was added to bupivacaine for spinal anaesthesia and had the advantage of increased duration of postoperative analgesia.
The 2022 Twin Earthquakes and Tectonic Environment in Kyaing Tong Basin, Eastern Myanmar
Authors: Aung Hla Hla , Swe Kye Mon Min
Published: November 2022

The first earthquake of magnitude 4.8 struck at 57 km south of Kyaing Tong, latitude 21.1141°N longitude 99.850°E, on 21st July 2022, at 16:40:08 UTC ( 11:07 a.m. local time ) at the depth of 10 km. Immediately after 30 minutes on the same day of 21st July 2022, the second earthquake with magnitude 5.9 occurred, 53 km south of Kyaing Tong at latitude 21.150°N 99.863°E, 17:07:26 UTC (11:37 a.m. local time) at 10 km depth. Focal mechanism solution for the first event was left-lateral strike-slip faulting and the second by normal faulting with a component of strike-slip component (United States Geological Survey). Many lesser aftershocks followed the main shocks and continued since July and still ongoing up to date in 2022. Twin earthquakes ruptured along the Wan Ha fault which bounds the southeast side of the Kyaing Tong basin, eastern Myanmar. The rupture propagated southward. The Kyaing Tong basin is one of the tectonic basins in the Paleo-Tethys suture zone in eastern Myanmar. These earthquakes are due to the movement of Wan Ha fault, affected the town Kyaing Tong where it caused some houses and schools collapsed. No casualty was reported. According to data from USGS, and other earthquake agencies, there is a clear increase in detected earthquakes, particularly smaller quakes of magnitude around ≥ 1.0 and ≥ 2.0 at shallower depth of 1000 meter. From the studies of satellite images, aerial photographs, shaded relief map and Digital Elevation Model map, several lineaments are visible and detailed mapping of these lineaments show the strike-slip faults in ENE-WSW direction and normal faults in NE-to NNE-striking direction. NW-SE extension is evident by the occurrence of brittle normal faults and NE-to ENE-oriented sinistral strike-slip fault. Within this zone is the trace of regional compression in a NE-SW direction. This region is presently undergoing active tectonic deformation, as indicated by current seismicity and earthquake focal mechanism solution.
Teacher–Student Ratio: The Status Quo in Public Secondary Schools in Ubungo Municipality, Tanzania
Authors: Bakar Ahmed S. , Mwila Prospery M.
Published: November 2022

The effectiveness of the teaching and learning process is typically judged by how well students perform. It has mainly been centred on the competence of teachers and their methods of instruction. However, there are exogenous factors, such as the number of students per teacher that affect effectiveness of the teaching and learning process. This study investigated the status of teacher-student ratio in secondary schools, in Ubungo Municipality. It was guided by two objectives; to assess the student-teacher ratio, and to identify the strategies that teachers use to manage large classrooms. The study employed a descriptive survey method with a combination of qualitative and quantitative research approaches in collecting, analyzing, and drawing conclusions from the data. The data collection instruments used were questionnaires, interviews, focus group discussions, and observation guide. The sample consisted of 170 respondents including ward education officers, heads of schools, academic teachers, teachers and students. The study revealed that public secondary schools in Ubungo Municipality are overcrowded because of the high teacher-student ratio. High student-teacher ratio leads to compromised teaching and learning process; it negatively affects classroom management practices, and makes it impossible for teachers to implement competence-based curriculum. Therefore, the study recommends that educational stockholders should improvise means of constructing more classrooms and/or establish new secondary schools, and employ adequate teachers to cater for an ever increasing number of students. An immediate solution would be for teachers to employ technical skills for the adaptation of large class sizes.
Iron and Zinc Bio-fortification through Agronomic Intervention in Chickpea (Cicer arietinum L.)
Authors: Sheshrao Hanwate Pavankumar , Kumar Sunil , Gajanand . , Birla Devilal , Choudhary Sanju , Singh Devendra
Published: November 2022

Essential micronutrients are required for humans to sustain proper physiological body processes and a healthy health condition. Micronutrient deficiencies, such as iron, zinc, and iodine, create global health concerns for people. Zinc and iron deficiency are frequent in chickpea growing regions across the world. Bio-fortification of pulse grains, especially with Fe and Zn by agronomic bio-fortification, is the simplest, most practical, and quickest method. During the Rabi season of 2019–20, a field experiment was done at the Bairiya Dhab Research Farm of Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur, Bihar, India, to find out effect on chickpea genotypes when Zn and Fe were added to the soil and the leaves. Two genotypes (GCP-105 and GNG-2264) and seven fertilization treatments (control, 0.5% Zn, 0.5% Fe, soil application of Zn and Fe, 25 and 15 kg/ha, respectively) were used in a split plot design with three replications. The GNG-2264 variety had a significantly higher plant height, yield and yield characteristics, such as number of pods per plant, test weight, seed and straw yield and economics viz. gross return, net return (62860 and 37986 ₹/ha), and B: C ratio (2.52) than GCP-105. Among the fertilization treatments, RDF + Zn (0.5%) and Fe (0.5%) foliar spraying at the pre-flowering and pod development stage recorded significantly higher growth and yield parameters viz., plant height (59.89 cm), number of pods/plant (22.31), seed yield (1283 kg/ha) and straw yields 2433 kg/ha), and quality parameters such as zinc and iron content in seed (31.84 and 17.40 ppm) and straw (72.26, 21.79 ppm, respectively) and economics in term of gross return, net return, and B: C ratio.
Yield and Economics of Kharif Onion (Allium cepa L.) under Front Line Demonstration in Eastern Plain Zone of Uttar Pradesh, India
Authors: Srivastva Rajneesh , Meena Kamlesh , Tiwari Ajay , Singh Neeraj , Behera T. K.
Published: November 2022

Aim: To disseminate the technology among the farmers through front line demonstration on Kharif onions for enhanced the production and fetching the more income.

Study Design: Not applicable.

Place and Duration of Study: ICAR-IIVR-Krishi Vigyan Kendra, Deoria, conducted front-line demonstrations on kharif onion at farmers' fields during the kharif season 2017, 2018, and 2019.

Methodology: Conducted 33 front-line demonstrations at farmers' fields during the study period. The yield data were recorded.

Results: To increase the output of onions through enhanced production technology, 33 front line demonstration on kharif onion were conducted. According to the demonstrations that were undertaken, the improved variety of kharif onions (NHRDF Agrifound dark Red) produced an average yield of 274.4 q/ha, which was greater than the average yield of   check (N-53) i.e. 228.83 q/ha. The average yield improvement over farmer techniques was 19.91%. It was noted that the average extension gap was 45.57 q/ha. The economics of the data showed that, on average, in demonstrations, gross returns were (277453.3/ha), net returns were (191184/ha), and benefit cost ratio was (3.2) as opposed to  check (Niphad-53), where gross returns were 204160/ha, net returns were 122423.3/ha and benefit cost ratio was (2.5).

Conclusion: The average yield enhancement over farmer techniques was 19.91%. It was noted that the average extension gap was 45.57 q/ha. The economics of the data showed that, on average, in demonstrations, gross returns were (277453.3/ha), net returns were (191184/ha), and benefit cost ratio was (3.2). Front line demonstration is one of the most important tools for technology transfer to the farmers at the grassroots level that has a significant effect on the horizontal spread of technology as well as build up the strong interaction with the farmer communities.
A Study on Geo-morphological Analysis and Risk Assessment Method Using Geospatial Information
Authors: Kim Byung Ju , Park Seon Jung , Choi Il Hoon , Park Seol Hwa , Park Seung Min , Seo Heui Jung
Published: November 2022

Rock platforms and TTP (breakwater) are dangerous environments commonly subject to tidal and high wave energy on the open coast. This paper is a study on risk assessment to provide risk information, which is a representative method for preventing coastal safety accidents. Risk assessment based on geo-morphological information was conducted for the Halmi-Halabi rock platform in Anmyeon-eup, Taean-gun, Chungcheongnam-do. As a result of the risk assessment in 16 directions, the risk was evaluated high in the NE, ENE, S, SSW, and W directions, where there are many sections with slopes exceeding ±20o, and the NW direction was the lowest. Geo-morphology on rock platform is central to understanding what makes one stretch of complex coastline more hazardous than another, and it can be used to create site-specific morphological risk item. In particular, it will be assisting coastal managers in an effort to reduce the number of injuries and drowning incidents by providing hazard information to assess the relative risk.
Characteristics of Local Scour Around the Double Pile in Waves
Authors: Oh Hyun Sik , Lee Ho Jin
Published: November 2022

Scour in a flow field affected by waves, such as river estuaries or shallow waters, is more difficult to predict than scour in a currents. The main issue in predicting the scour around circular files, such as undersea bridges, is the maximum scour depth and the point of occurrence. In the case of two or more adjacent circular piles, the location and depth of maximum scour according to the spacing between piles and the arrangement method show a lot of difference compared to the case of a single pile. In this paper, the KC number are calculated as dimensionless variables representing the strength of the flow. And the correlation between pile gap size and relative scour depth was analyzed.
Moral hazard and nonmarket institutions
Authors: Arnott Richard , Stiglitz Joseph E.
Published: July 2002

We examine a situation in which insurance is characterized by moral hazard. When market insurance is provided, supplementary mutual assistance between family and friends (unobservable to market insurers) will occur. When nonmarket issuers have no better information than market insurers, the mutual assistance not only crowds out market insurance but is also harmful and therefore dysfunctional. Alternatively, when nonmarket insurers can observe each other's effort perfectly, mutual assistance is beneficial. These results point to the potential importance of peer-monitoring mechanisms in mitigating moral hazard. (JEL 026) (reprinted with permission)
Post‐transplant lymphoproliferative disease in children
Authors: Collins M. H. , Montone Kathleen T. , Leahey Ann M. , Hodinka Richard L. , Salhany Kevin E. , Kramer Deborah L. , Deng C. , Tomaszewski John E.
Published: July 2002

Abstract: Epstein–Barr virus (EBV)‐driven post‐transplant lymphoproliferative disease (PTLD) is an important cause of morbidity and mortality following transplantation, and it occurs more frequently in children than in adults. Of 22 (5%) children at our institution who developed tissue‐proven PTLD 1–60 months (mean 16.5 months) following organ transplant, 11 died: nine of these 22 patients developed PTLD between 1989 and 1993, and seven (78%) died; the remaining 13 developed PTLD between 1994 and 1998, and four (31%) died (p = 0.08). All nine patients who developed PTLD < 6 months after transplant died, but 11 of 13 patients who manifested disease ≥ 6 months after transplant survived (p = 0.0002). Ten of 11 (91%) survivors, but only two of eight (25%) children who died, had serologic evidence of EBV infection at the time of PTLD diagnosis (p = 0.04). EBV seroconversion identified patients at risk for developing PTLD, but also characterized patients with sufficient immune function to survive EBV‐related lymphoid proliferation. In situ hybridization for EBER1 mRNA was diagnostically helpful because it detected EBV in tissue sections of all 20 patients with B‐cell PTLD, including those with negative serology.
Temperature‐related fluid extravasation during cardiopulmonary bypass: An analysis of filtration coefficients and transcapillary pressures
Authors: Heltne J. K. , Bert J. , Lund T. , Koller M.‐E. , Farstad M. , Rynning S. E. , Husby P.
Published: July 2002

Background: Cardiopulmonary bypass (CPB) as used for cardiac surgery and for rewarming individuals suffering deep accidental hypothermia is held responsible for changes in microvascular fluid exchange often leading to edema and organ dysfunction. The purpose of this work is to improve our understanding of fluid pathophysiology and to explore the implications of the changes in determinants of transcapillary fluid exchange during CPB with and without hypothermia. This investigation might give indications on where to focus attention to reduce fluid extravasation during CPB.

Methods: Published data on “Starling variables” as well as reported changes in fluid extravasation, tissue fluid contents and lymph flow were analyzed together with assumed/estimated values for variables not measured. The analysis was based on the Starling hypothesis where the transcapillary fluid filtration rate is given by:

JV=Kf[Pc−Pi−σ(COPp−COPi)]. Here Kf is the capillary filtration coefficient, σ the reflection coefficient, P and COP are hydrostatic and colloid osmotic pressures, and subscript ‘c’ refers to capillary, ‘i` to the interstitium and `p’ to plasma.

Results and conclusion: The analysis indicates that attempts to limit fluid extravasation during normothermic CPB should address primarily changes in Kf, while changes in both Kf and Pc must be considered during hypothermic CPB.
Reading Heidegger and interpretive phenomenology: a response to the work of Michael Crotty
Authors: Darbyshire Philip , Diekelmann John , Diekelmann Nancy
Published: July 2002

In a recent paper in Nursing Inquiry and in his other work, Michael Crotty was severely critical of much interpretive nursing scholarship and especially of some nurse scholars’ interpretations of the work of Martin Heidegger. In this paper we respond to Crotty’s attempt to set out what Heidegger ‘actually says’[sic] in relation to tradition, culture, destruction, das Man and everydayness. We suggest that Crotty took a narrow, existentialist view of Heidegger’s work and that this view was often misguided and poorly informed. We show not only that an alternative understanding of Heidegger’s work in these important areas is possible, but that this interpretation is strongly supported by a deeper and wider reading of Heidegger’s own work and of the secondary literature of Heideggerian scholarship.
Neuroanatomy of the penile portion of the human dorsal nerve of the penis
Authors: Yang  , Bradley
Published: July 2002

Objective

 To determine the distribution of the dorsal nerve of the penis (DNP), the principal somatosensory nerve innervating the phallus, along the penile shaft and within the glans penis.

Materials and methods

 The DNP was dissected in human autopsy specimens, using low magnification, following the course of the nerve from the symphysis pubis into the glans penis.

Results

 The shaft and glans were innervated by separate populations of axons. The lateral and ventral portions of the penile shaft were innervated by branches arcading from the dorsal midline radiating toward the ventral surface. These branches were very variable and some were seen to penetrate the corpus spongiosum. The axons innervating the glans were constant in a dorsal, midline location along most of the penile shaft, and once within the glans, there was abundant branching. Undulations in the nerves were noted along the penile shaft.

Conclusions

 The lateral arcading branches of the DNP provide a sensory pathway on the ventral and lateral penile shaft, and the termination of the fibres at the corpus spongiosum is consistent with pudendal innervation of the penile urethra. The distinct pattern of innervation of the glans emphasizes the role of the glans as a sensory structure. These findings may aid in planning penile surgical procedures.
Universal energy dependence of physical and ion-enhanced chemical etch yields at low ion energy
Authors: Steinbrüchel Christoph
Published: July 2002

Physical and ion-enhanced chemical etch yields are shown to be a linear function of the square root of the ion energy down to the etching threshold for self-sputtering of metals, sputtering of metals by noble gas ions, sputtering of Si and SiO2 by noble gas and reactive ions, and ion beam enhanced chemical etching of Si. The threshold energy must be taken into account for a quantitative description of etch yields even at intermediate ion energies. The relationship between the dependence of etch yields on ion energy and incident angle is also discussed.
Detailed analysis of second-harmonic generation near 10.6 μm in GaAs/AlGaAs asymmetric quantum wells
Authors: Boucaud P. , Julien F. H. , Yang D. D. , Lourtioz J-M. , Rosencher E. , Bois P. , Nagle J.
Published: July 2002

We report on the observation of resonant intersubband second-harmonic generation in asymmetric GaAs/AlGaAs quantum wells using a cw or Q-switched tunable CO2 laser as the pumping source. The dependence of the second-harmonic intensity with the pump photon wavelength is presented for the first time. A Lorentzian-like second-harmonic line shape is found with a maximum at 10.9 μm and a linewidth of 0.4 μm (4.1 meV). These results are in good agreement with theoretical predictions. The expected quadratic dependence of the second-harmonic conversion efficiency with pump intensity is well verified for intensities up to 150 kW/cm2. The calibrated second-harmonic power reaches 0.13 μW for a cw pump power of 0.8 W. The value of 7.2×10−7 m/V deduced for the second-order nonlinear susceptibility is about 1900 times greater than that found in bulk GaAs.
Use of high T
c superconductors for far-infrared Fabry–Perot resonators
Authors: Renk K. F. , Betz J. , Schützmann J. , Prückl A. , Brunner B. , Lengfellner H.
Published: July 2002

In this letter we report on the application of high Tc superconductors for fabrication of far-infrared Fabry–Perot resonators. Thin films of YBa2Cu3O7−δ deposited on MgO substrates by the laser ablation technique were used as reflectors. Two films on two different MgO plates were arranged parallel at a distance determining the lowest order resonance. We demonstrate operation of a resonator in a frequency range (up to about 300 cm−1) in which MgO is transparent at low temperature.
Concentration of atomic hydrogen diffused into silicon in the temperature range 900–1300 °C
Authors: McQuaid S. A. , Newman R. C. , Tucker J. H. , Lightowlers E. C. , Kubiak R. A. A. , Goulding M.
Published: July 2002

Boron-doped Czochralski silicon samples with [B]∼1017 cm−3 have been heated at various temperatures in the range 800–1300 °C in an atmosphere of hydrogen and then quenched. The concentration of [H-B] pairs was measured by infrared localized vibrational mode spectroscopy. It was concluded that the solubility of atomic hydrogen is greater than [Hs] = 5.6 × 1018 exp( − 0.95 eV/kT)cm−3 at the temperatures investigated.
Atomic force microscope study of boundary layer lubrication
Authors: O’Shea S. J. , Welland M. E. , Rayment T.
Published: July 2002

An atomic force microscope is used to investigate the lubrication properties of a simple surfactant (n-dodecanol) on mica at 24 °C. The liquid becomes strongly layered as it is confined between the tip and the mica and a bilayer structure was often observed. The lubrication properties of the adsorbed molecules are clearly evident in the very low friction forces observed at appreciable applied loads (∼100 MPa). It is only when the last layer of molecules is removed that a significant friction signal is observed. It appears that the tip-mica interaction is dominated by adhesive forces and hence the measured friction and normal forces are strongly influenced by the effective contact area of the tip.
Modulation-doped n-type Si/SiGe with inverted interface
Authors: Ismail K. , Chu J. O. , Saenger K. L. , Meyerson B. S. , Rausch W.
Published: July 2002

We report the growth of n-type modulation-doped Si/SiGe with the doped SiGe supply layer underneath the strained Si channel. The mobility and charge density are measured in samples with 2- and 3-nm-thick spacers using gated Hall measurements. A peak room temperature mobility of 2200 cm2/V s is measured at a sheet density of 2.5×1012 cm−2. The measurements indicate a clear mobility modulation especially near threshold. Our layer design allows the gate to induce a sheet charge density of up to 3.2×1012 cm−2, before any significant reduction in the mobility is observed.
Spatial collection efficiency of a solar cell
Authors: Sinkkonen J. , Ruokolainen J. , Uotila P. , Hovinen A.
Published: July 2002

The spatial collection efficiency C(z) is the probability that a photon absorbed at the point z in the cell will yield a charge carrier into the current. The C function is obtained from the spectral response by means of the inverse Laplace transformation. It gives important information on the cell parameters such as diffusion length, junction depth, surface recombination velocity, etc. Examples of c-Si and thin-film CdS/CdTe cells are given.
Photomixing up to 3.8 THz in low-temperature-grown GaAs
Authors: Brown E. R. , McIntosh K. A. , Nichols K. B. , Dennis C. L.
Published: July 2002

Low-temperature-grown (LTG) GaAs is used as an optical-heterodyne converter or photomixer, to generate coherent continuous-wave output radiation from microwave frequencies up to 3.8 THz. The photomixer consists of an epitaxial layer of LTG GaAs with interdigitated electrodes fabricated on the top surface. Terahertz photocurrents are generated in the gaps between the electrodes, and power is radiated into free space through a three-turn self-complementary spiral antenna. In a photomixer having a 0.27-ps electron-hole lifetime and small electrode capacitance, the output power is practically flat up to about 300 GHz and then rolls off at a rate of approximately 12 dB/oct.
A simple fiber optic level sensor using fluorescent fibers
Authors: Augousti A. T. , Mason J. , Grattan K. T. V.
Published: July 2002

A simple ‘‘proof-of-principle’’ demonstration of the use of fluorescent optical fibers in an optical level sensor has been shown and results obtained over a sensing range of several hundred millimeters to an acceptable degree of accuracy for a low-cost, simple domestic or industrial device.
A powerful eyesafe infrared aerosol lidar: Application of stimulated Raman backscattering of 1.06 μm radiation
Authors: Carnuth W. , Trickl T.
Published: July 2002

A powerful infrared aerosol lidar operating at the eyesafe wavelength of 1.56 μm has been developed. More than 140 mJ per pulse are obtained from stimulated Raman backscattering narrow-band Nd:YAG laser radiation in deuterium. The mobile lidar system was successfully applied during the VAST and MAPTIP international aerosol field campaigns in 1992 and 1993. A range between 0.3 and more than 10 km is demonstrated for slant-path measurements in the presence of aerosols or cirrus clouds.
A compact electron-spin-polarization manipulator
Authors: Duden T. , Bauer E.
Published: July 2002

A compact electron-spin-polarization manipulator is described which allows one to align the polarization in any desired direction in space. The system delivers a focused electron beam of typically 3–5 keV. Its application in spin-polarized low-energy electron microscopy for the study of magnetic domain structures is briefly illustrated.
Ion-temperature measurement of indirectly driven implosions using a geometry-compensated neutron time-of-flight detector
Authors: Murphy T. J. , Lerche R. A. , Bennett C. , Howe G.
Published: July 2002

A geometry-compensated neutron time-of-flight detector has been constructed and used on Nova to measure ion temperatures from indirectly driven implosions with yields between 2.5 and 5×109 DD neutrons. The detector, which has an estimated respond time of 250 ps, was located 150 cm from the targets. Due to the long decay time of the scintillator, the time-of-flight signal must be unfolded from the measured detector signal. Several methods for determining the width of the neutron energy spectrum from the data have been developed and give similar results. Scattered x rays continue to be a problem for low yield shots, but should be brought under control with adequate shielding.
Progress on the multipulse Thomson scattering diagnostic on DIII-D
Authors: Stockdale R. E. , Carlstrom T. N. , Hsieh C. L. , Makariou C. C.
Published: July 2002

The DIII-D Thomson scattering diagnostic, operational since 1990, uses 8 Nd:YAG 20-Hz lasers to measure electron temperature and density profiles (40 spatial points) throughout the plasma discharge. Recent progress has enabled a new set of operating modes to better fulfill varying plasma physics requirements. Custom circuitry for laser control (programmable with 1 μs precision) has successfully replaced a previous scheme which used real-time 68030 software. Two new modes of operation have been demonstrated. Burst mode is useful to study a transient plasma event: a series of laser pulses are fired at a rate ≤10 kHz after an external asynchronous event trigger. Burst mode is also useful to synchronize the Thomson lasers with other systems, such as an asynchronous Michelson ECE diagnostic scanning near 40 Hz. Group mode allows a programmed set of lasers to fire simultaneously into the same (65 ns) data acquisition gate. Improved signal/noise then yields smaller statistical errors in the profile results. This provides profile data for lower density plasmas, such as those anticipated during fast wave current drive experiments. Plans for a new CCD-based laser alignment system for position monitoring and feedback control will also be presented.
Surface plasma source to generate high-brightness H− beams for ion projection lithographya)
Authors: Dudnikov V. G. , Derevyankin G. E. , Kovalevsky D. V. , Savkin V. Ya. , Sokolovsky E. A. , Guharay S. K.
Published: July 2002

A surface plasma source with Penning-type electrodes is developed to generate H− beams for ion projection lithography applications. The source presently runs in pulsed mode with a pulse width of about 1 ms and repetition rate of 10 Hz. The discharge and the extracted H− beam are maintained in stable, noiseless condition; gas pressure plays a critical role here. The maximum H− beam current density at the emission surface is about 1.7 A/cm2. Preliminary measurements suggest that the normalized brightness of the core beam is ∼1.7×1013 A/(m rad)2 and its perpendicular temperature is about 0.2 eV.
Advances in undulator technology at STI Optronics
Authors: Robinson K.E. , Challenger M.P. , Gottschalk S.C. , Quimby D.C.
Published: July 2002

Undulator and wigglers are an essential basis for synchrotron radiation and free-electron laser systems. Wiggler and undulator design concepts for producing higher magnetic field strength with improved field quality are reviewed. Shim tuning methods have permitted magnetic field tolerances, including pole-to-pole field uniformity, trajectory straightness, and higher order moments, to be controlled to low levels as needed for various applications. A key figure of merit is the optical phase error, which determines the coherence of the light generated in the device. Coherence is a strict requirement for maintaining spectral intensity in synchrotron radiation sources with low emittance and maximizing gain in free-electron lasers.
Status of the ESRF insertion devices
Authors: Chavanne J. , Elleaume P. , Van Vaerenbergh P.
Published: July 2002

The cumulated length of insertion devices in operation at the ESRF reaches 44 m, segmented in 29 devices serving 20 beamlines. The majority are conventional vertical sinusoidal field devices made of permanent magnet. Exotic insertion devices have been installed, such as helical undulators with variable polarization, asymmetric wigglers, a variable gap chamber short undulator and a 5 T superconducting wiggler. With the new low emittance lattice, a single undulator segment generates hard x-rays with a record brilliance of 2x1019 phot./s/.1%/mm2/mr2. All devices have been produced in-house, and the methods of field correction based on shimming are summarized. Recent developments concerning the design of undulator/wiggler terminations are described, which minimize or eliminate the need for electromagnet correctors on hybrid wigglers or allow the implementation of variable length segmented undulators.
Two highly sensitive microwave cavity spectrometers
Authors: Dumesh B. S. , Surin L. A.
Published: July 2002

A description is presented for two unconventional highly sensitive spectrometers operating in the decimeter-wave region (90–450 MHz) and millimeter-wave region (90–150 GHz), respectively. In both cases a resonant cavity is used as an absorption cell. Either design combines high sensitivity with high resolution and wide spectral range. The radio frequency spectrometer allows measuring of extremely low absorption quantity 3×10−12 cm−1 in combination with high spectral resolution of order 1 kHz with the radio frequency–microwave double resonance method. The gas cell is a coaxial cavity (Q≊103) with a diameter of 40 cm and length about a wavelength. The millimeter-wave spectrometer utilizes an orotron oscillator as the tunable, coherent source of radiation from 90 to 150 GHz. A gas cell is placed into a high quality (Q≊104) Fabry–Pérot resonator of the orotron, and the absorption signal is detected by variation of the orotron electron current in the collector circuit. The sensitivity limit of (2–5)×10−10 cm−1 is achieved with Stark modulation as well as source frequency modulation. Some results of successful application of both designs in molecular spectroscopy are presented, and potential use of the millimeter-wave cavity spectrometer as a gas analyzer with a detection limit better than 1 ppm is briefly discussed.
Design and testing of a new, simple continuous bent sagittally focusing monochromator (abstract)
Authors: Kycia Stefan , Inoue Kazuhiko , Shen Qun
Published: July 2002

A continuous bent sagittally focusing monochromator has been designed and built. The monochromator is compatible with the present single-point bender apparatus designed for polygonal (ribbed) triangular sagittally focusing monochromators. This monochromator implements a new design concept taking advantage of a tapered rectangular wafer to allow for sagittal bending while simultaneously minimizing anticlastic bending. The monochromator was optimized to operate at x-ray energies in the range of 5 to 25 keV. The design was derived from finite element analysis using ANSYS. The monochromator performance was tested by means of an apparatus implementing an x-ray tube source and a double-crystal configuration. This method yields precise contour maps of the entire monochromator surface. Details of the monochromator design, test apparatus, and corresponding results will be presented.
Design and construction of planar mm-wave accelerating cavity structures
Authors: Kang Y.W. , Feinerman A.D. , Kustom R.L. , Nassiri A. , Song J.J.
Published: July 2002

Feasibility studies on planar millimeter-wave cavity structures have been made. The structures could be used for linear accelerators, free-electron lasers, mm-wave amplifiers, or mm-wave undulators. The cavity structures are intended to be manufactured by using DXL (deep x-ray lithography) microfabrication technology. The frequency of operation can be about 30 GHz to 300 GHz. For most applications, a complete structure consists of two identical planar half structures put together face-to-face. Construction and properties of the constant gradient structures that have been investigated so far will be discussed. These cavity structures have been designed for 120 GHz 2π/3-mode operation.
Design and analysis of the internally cooled silicon mirrors and benders for wiggler sources at the Advanced Photon Source (abstract)
Authors: Schildkamp W. , Jaski Y. , Tonnessen T. , Douglas G.
Published: July 2002

When silicon single crystal mirrors are bent to cylindrical figures of typically 6 km bending radius, the moments needed are very small and easy to disturb by cooling attachments to the sides of the mirror. Hence, we decided to abandon the conventional concept of cooling plates attached to the sides of the mirrors and instead have chosen to use internal water channels. We present here the design of mirrors with cooling channels near the neutral axis of the silicon beam that have a rather thick ‘‘hot wall.’’ The results of this analytical work are nonintuitive, regarding the stresses produced by wiggler heating. The design path chosen minimizes figure errors due to coolant pressure variations and residual stresses from machining and bonding of multiple layers of silicon. The geometry of the water channels avoids water-to-vacuum seals and uses the mirror bender as the coolant manifold. Engineering efforts, which reduce the bending stresses at bender-to-silicon interface by a factor of five, will be presented. The complete mirror bender and motion control mechanics will be shown.
Design of a high precision mirror-rotation system at the Advanced Photon Source
Authors: Barraza J. , Shu D. , Yun W. , Kuzay T. M.
Published: July 2002

A prototype of a high precision rotation system has been designed, built, and tested for a horizontal deflecting mirror for the sector 2 undulator beamline at the Advanced Photon Source. The UHV high heat load mirror, which is the first optical element in the first optics enclosure, diverts undulator white beam to the downstream optics and experimental stations up to 47 meters away. Submicroradian positioning of this deflection arm is essential due to the position accuracy requirements at the experiment station and is accomplished using a differential-style actuator with a frictionless rotation platform mounted externally to the mirror chamber. The differential actuator combines a high gear-ratio mechanical drive with a series of bellows to achieve near-zero-backlash positioning. As a result, submicroradian resolutions are possible without the use of closed-loop controls. This paper presents the mechanical design and specifications of this system and discusses the prototype test results.
Toward the development of high resolution synchrotron x-ray diffraction tomography of polycrystalline materials (abstract)
Authors: Stock Stuart R. , Piotrowski D. P. , Guvenilir A. , Patterson C. R. , Haase J. D. , Rek Zofia U.
Published: July 2002

In understanding the macroscopic response of polycrystalline structural materials to loading, it is frequently essential to know both the three-dimensional distribution of strain and of microtexture. The methods must be nondestructive, however, if the evolution of quantities, such as strain at a fatigue crack tip, are to be studied. This paper describes approaches for high resolution synchrotron x-ray diffraction tomography of polycrystalline materials. Preliminary experiments are reported on partially cracked compact tension samples of Al-Li 2090 and on model samples of randomly packed, millimeter-sized single crystals. Polychromatic beams collimated to diameters as small as 30 μm have been used, and collecting the spatial distribution of diffracted intensity on image storage plates as a function of sample-to-detector separation allowed inference of the depth of the volume elements contributing to diffraction. The precision to which one can determine the depths of volume elements will be discussed as well approaches for three-dimensional, nondestructive strain mapping.
Installation of the MAXIMUM microscope at the ALS
Authors: Ng W. , Perera R.C.C. , Underwood J.H. , Singh S. , Solak H. , Cerrina F.
Published: July 2002

The MAXIMUM scanning x-ray microscope, developed at the Synchrotron Radiation Center (SRC) at the University of Wisconsin – Madison, was implemented on the Advanced Light Source (ALS) in August of 1995. The microscope’s initial operation at SRC successfully demonstrated the use of a multilayer-coated Schwarzschild objective for focusing 130 eV x-rays to a spot size of better than 0.1 micron with an electron energy resolution of 250 meV. The performance of the microscope was severely limited because of the relatively low brightness of SRC, which limits the available flux at the focus of the microscope. The high brightness of the ALS is expected to increase the usable flux at the sample by a factor of 1000. We will report on the installation of the microscope on bending magnet beamline 6.3.2 at the ALS and the initial measurement of optical performance on the new source, and preliminary experiments on the surface chemistry of HF-etched Si will be described.
Phase space analysis of a 4-bounce high resolution monochromator
Authors: Popovici M.
Published: July 2002

A high resolution 4-bounce monochromator with nested pairs of channel-cut Si (422) and (10 6 4) crystals in (+n,+m,−m,−n) configuration was recently implemented for signal-to-background enhancement in coherent nuclear resonant scattering measurements. In this paper, it is analyzed by using methods that have been developed for neutron optics. The overall throughput can be improved by bending the outer (422) pair. The bending relaxes the usual requirements on the reflection asymmetry of flat crystals, so that both (422) crystals can be set in beam condensation geometry. This results in large gains in flux at moderate gains in total beam intensity.
Optimization of monochromator crystal bending designs using computer simulations
Authors: Frenkel A. , Barg B. , Heald S. , Kim K.H. , Brown F. , Stern E.A.
Published: July 2002

Sagittal focusing of a synchrotron radiation beam by cylindrically bending the second crystal in a double-crystal monochromator is an important way of increasing beam density at the sample posiion. In this paper we describe results obtained by finite element analysis of various optimized Si (111) crystal shapes. For the bending magnet and wiggler sources, we analyzed ribbed crystals and found conditions at which the sagittal curvature is cylindrical and the anticlastic effect is minimized. For the undulator A source, we found that a single slot in the center of a thick plate would be sufficient to eliminate the anticlastic effect and ensure cylindrical sagittal bending. Autofocusing of the beam by means of a trapezoidal slot was investigated, and simulation results are discussed.
TEXRAY™ CCD detectors (abstract)
Authors: Ferrara Joseph D. , Crane K. , Gardner R. D. , Jones N. D. , Pflugrath J. W. , Troup J. M. , Vincent B. R.
Published: July 2002

We have designed and built TEXRAYTM CCD detectors with properties suitable for single-crystal data collection on both small molecules and macromolecules. Characterization and use of 70 mm×70 mm and 140 mm×140 mm aperture detectors will be discussed in the context of the synchrotron source.
Cryogenically cooled monochromators for the Advanced Photon Source (invited)
Authors: Mills Dennis M.
Published: July 2002

The use of cryogenically cooled monochromators looks to be a very promising possibility for the Advanced Photon Source. This position has recently been bolstered by several experiments performed on beamlines at the ESRF and CHESS. At the ESRF, several crystal geometries have been tested that were designed for high power densities (≳150 W/mm2) and moderate total absorbed powers (<200 W). These geometries have proven to be very successful at handling these power parameters with measured strains on the arc-second level. The experiments performed at CHESS were focused on high total power (≳1000 W) but moderate power densities. As with the previously mentioned experiments, the crystals designed for this application performed superbly with no measurable broadening of the rocking curves on the arc-second level. These experiments will be summarized and, based on these results, the performance of cryogenic monochromators for the APS will be assessed.