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Soil biota refers to a highly diverse assemblage of organisms that spend at least part of their life cycle in or on the soil. As their numerical diversity suggests, soil biota undertake a wide range of functions, including the detrimental activities of pathogens, parasites, and other agricultural pests. Fertilizer, tillage, and pesticide inputs account for as much as 33, 17, and 10 percent, respectively, of total energy use in US agriculture. Soil organisms may inhabit surface layers of soil and litter or deeper soil horizons, or move throughout the soil profile. The total biomass of the soil biota constitutes a relatively small fraction of total soil organic matter. The functioning of detritus food webs is driven by inputs of organic matter. Cultivation of undisturbed soil brings about a number of changes in community structure and activity of indigenous soil biota. Some physical and chemical manipulations alter habitat conditions directly and may be useful for stimulating or suppressing biotic activity.

While it is now possible to image the three-dimensional structure of soil using high-resolution tomography, none of the techniques can simultaneously image the distribution of the resident soil microbes. This means that it is not possible to visualize soil microbes in their habitat. Consequently, the impact of soil structure on microbially mediated processes cannot be reliably modeled. Biological thin sections offer the opportunity to simultaneously image microbes in structure but are necessarily restricted to two dimensions. Therefore a methodology is required to simulate three-dimensional structures from two-dimensional thin sections of soil that is extendable to simulate the spatial distribution of a range of soil components. We developed a model that is capable of using data gathered from two-dimensional sections to predict the three-dimensional structure of soil. An object-oriented approach to modeling was used to allow the individual representation of each structure voxel. This allows the model to encapsulate both data, presented here, and the subsequent addition of components such as microbial distribution and related diffusion-respiration processes together in a three-dimensional lattice of voxels. The model was validated using data derived from three-dimensional x-ray tomography images of soil structure, and using two-dimensional sections through that data set to predict three-dimensional structure. A range of metrics was used to compare the modeled and imaged three-dimensional structures. The comparison shows that the metrics for the modeled structures agree with those derived from the three-dimensional images for higher porosities, but that systematic differences occur for the lowest porosity soils (

Tracheal intubating conditions were assessed in 112 children after induction of anaesthesia with propofol and remifentanil 1.0, 2.0 or 3.0 micro g.kg-1. Subjects in a control group were given propofol and mivacurium 0.2 mg.kg-1. Haemodynamic and respiratory parameters were recorded. Plasma catecholamine levels were measured in a subgroup of 40 children. Intubating conditions were acceptable in 14/28 (50%), 18/26 (69%) and 22/27 (82%) in those subjects given remifentanil 1.0, 2.0 or 3.0 micro g.kg-1, respectively, and in 27/28 (96%) of the control group. Intubating conditions in subjects given remifentanil 3.0 micro g.kg-1 were better than in those given remifentanil 1.0 micro g.kg-1 (p < 0.05). There were no significant differences in intubating conditions between those given remifentanil 3.0 micro g.kg-1 and the control group. Systolic blood pressure and heart rate increased in response to tracheal intubation in subjects given remifentanil 1.0 micro g.kg-1 and in the control group (p < 0.05). Time to resumption of spontaneous respiration was prolonged in subjects given remifentanil 3.0 micro g.kg-1 (p < 0.001). In conclusion, remifentanil 2 micro g.kg-1 provides acceptable intubating conditions and haemodynamic stability without prolonging the return of spontaneous respiration.

Objective This study was undertaken to test the hypothesis that abnormalities of the subchondral bone can result in osteoarthritis (OA). Methods We used a knockin model of human osteogenesis imperfecta, the Brittle IV (Brtl) mouse, in which defective type I collagen is expressed in bone. OA in individual mice was documented by micro–magnetic resonance imaging (micro-MRI) and micro–computed tomography (micro-CT). Alterations in the knee joints were confirmed by histopathologic and immunohistochemical analysis. In addition, atomic force microscopy (AFM) was used to assess the ultrastructure of the articular cartilage and subchondral bone matrix. Results Brtl mice had decreased integrity of bone but initially normal articular cartilage. However, by the second month of life, Brtl mice developed alterations of the cartilage that were characteristic of OA, as documented by micro-CT, micro-MRI, and histologic evaluation. In addition, chondrocyte loss and breakdown of the collagen matrix in the residual cartilage were demonstrated using AFM. Conclusion The Brtl mouse model demonstrates that progressive destruction of articular cartilage characteristic of OA may be secondary to altered architecture of the underlying subchondral bone.

We compared the analgesic efficacy and safety of remifentanil and pethidine via patient controlled analgesia for women in established uncomplicated labour. Women received either remifentanil 40 microg with a 2-min lockout (n = 20) or pethidine 15 mg with a 10-min lockout (n = 19). Visual analogue scores for pain during the study and for overall pain were similar for both groups (mean (SD) 6.4 (1.5) cm for remifentanil and 6.9 (1.7) cm for pethidine). The area under the curve for visual analogue scores of satisfaction with analgesia was higher for remifentanil than for pethidine (p = 0.001). Maternal arterial oxygen saturation was similar in both groups. Neurologic and Adaptive Capacity Scores at 30 min were higher for remifentanil than for pethidine (median (interquartile range [range]) 36 (34.5-37 [32-39]) vs 34 (33-35 [30-35]), respectively; p = 0.003).

Heterosexual transmission of HIV is a growing problem for women, but many women do not know how their partners acquired HIV. We described a group of HIV-infected men and women, and focused on: (1) sexual identity and bisexual behaviour in men, and (2) the proportion of women who acknowledged having a bisexual male partner. This study examined HIV-infected persons who participated in a cross-sectional interview project from January 1995 through July 2000; 5,156 men who have sex with men (MSM), and 3,139 women. The proportion of MSM who reported having sex with women (MSM/MSW) varied by race: 34% of black MSM, 26% of Hispanic MSM, and 13% of white MSM. While 14% of white women acknowledged having a bisexual partner, only 6% of black and 6% of Hispanic women reported having a bisexual partner. Most behaviourally bisexual men identified as either bisexual (59%) or homosexual (26%). Among MSM/MSW, 30% had more female partners than male partners, while only 10% had more male partners than female partners. These data suggest that bisexual activity is relatively common among black and Hispanic HIV-infected MSM, few identify as heterosexual, and their female partners may not know of their bisexual activity.

Levonorgestrel implants (Norplant) and medroxyprogesterone acetate injections (Depo-Provera) represent additional contraception options for adolescents. The purpose of this study was to examine prospectively clinical profiles among adolescents who chose one of the two long-term contraceptives compared with profiles among those who chose the combined oral contraceptive pill (OCP).Girls who needed contraception and did not require confidentiality were presented with a contraceptive menu consisting of Norplant (n = 58), Depo-Provera (n = 66), or OCP (n = 75). At baseline and follow-up visits over 6 months, patients were interviewed regarding gynecologic history, side effect symptoms, and satisfaction. The average age of subjects was 15.5 years (range 11 to 20 years); 66% were African-American and 34% white.Significantly more teens who chose Depo-Provera (73%) reported having used some method of birth control previously than those selecting either Norplant (30%) or OCP (26%). Adolescents who chose either Norplant (34%) or Depo-Provera (43%) were significantly more likely to have been pregnant previously than those choosing OCP (12%). Those selecting Depo-Provera were significantly more likely to report a history of genital infection with Chlamydia trachomatis (42%) than those in the other two contraceptive groups (22%). Prevalences of reported recent depression and fatigue before initiation of treatment were high, exceeding 35% across the three groups. A total of 105 and 40 adolescents were assessed at 3 and 6 months, respectively. At follow-up, more than 80% of OCP users maintained regular menstrual cycles, whereas over 80% of those choosing Norplant or Depo-Provera had disrupted cycles. Complaints of nausea and dizziness among Norplant users and fatigue among Depo-Provera and OCP users increased significantly between the baseline and follow-up visits. Reports of local reactions to the Norplant device were common but not clinically significant. Blood pressure readings, facial acne, and body mass index did not change over time in any treatment group. Subjects in the Norplant and Depo-Provera groups appreciated freedom from daily compliance to maintain contraceptive effectiveness and the "hidden" nature of the method. Appointment compliance at the end of 6 months was 78% for Depo-Provera, 40% for Norplant, and 46% for OCP.The implant and injection forms of contraception appear to be especially popular among girls with previous pregnancies or birth control use. The common occurrences of medical symptoms and sexually transmitted diseases before initiation of therapy underscore the importance of baseline evaluation. Norplant users may be warned about nausea and dizziness as well as minor local symptoms around the insertion site and unpredictable uterine bleeding patterns. Adolescent patients choosing Depo-Provera may expect amenorrhea by the end of 6 months of therapy along with possible fatigue. Early intervention may be needed with adolescents who choose Norplant or OCP to encourage better compliance with follow-up appointments.

The subcutaneous (sensory) portion of the superficial peroneal nerve was dissected in 25 cadaver lower limbs under loupe magnification. Three distinct branching pattern types were noted. Type A (72%) consisted of a pattern where the nerve penetrated the crural fascia to become subcutaneous at an average distance of 12.3 cm proximal to the ankle joint, then divided at a mean distance of 4.4 cm proximal to the ankle into two major branches: a large medial dorsal cutaneous nerve and a smaller more laterally located intermediate dorsal cutaneous nerve. Type B (16%) consisted of a pattern where both the medial and intermediate dorsal cutaneous nerve arose independently from the superficial peroneal nerve, with the medial dorsal cutaneous nerve having a similar course to that found in Type A, while the intermediate dorsal cutaneous nerve penetrated the crural fascia posterior to the fibula 5.5 cm proximal to the ankle joint and coursed medially to cross the lateral aspect of the fibula at mean distance 4.5 cm above the ankle joint. Type C (12%) consisted of a pattern where the medial dorsal cutaneous nerve and the intermediate dorsal cutaneous nerve arose independently and the medial dorsal cutaneous nerve coursed similar to that in Type A; however, the intermediate dorsal cutaneous nerve penetrated the crural fascia anterior to the fibula an average of 4.9 cm above the ankle joint and continued in close proximity to the anterior fibular border. In all patterns the mean diameters of the medial dorsal cutaneous nerve and intermediate dorsal cutaneous nerve at the ankle were 2.9 mm and 2 mm, respectively. At the level of the malleoli, the medial dorsal cutaneous nerve was located approximately one half the distance from the lateral malleolus to medial malleolus while the intermediate dorsal cutaneous nerve was approximately one third the distance. Appreciation of these branch patterns and the quantified relationships should assist nerve protection during surgical procedures as well as aid rapid nerve isolation for exploration or decompression. Branches especially at risk for iatrogenic injury include: (1) the intermediate dorsal cutaneous nerve of Type B where the nerve crosses the lateral surface of the distal fibula; (2) the intermediate dorsal cutaneous nerve of Type C where the nerve travels adjacent to the anterior border of the fibula; and (3) the intermediate dorsal cutaneous nerve and the medial dorsal cutaneous nerve at the level of the ankle, where they are at risk during anterior ankle arthrotomy or arthroscopy.

1054 Background: This international trial studied the efficacy and safety of Cap plus Enz in treating advanced BrCa. Methods: Eligible pts (advanced BrCa, prior anthracycline and taxanes, ≤2 prior chemotherapy regimens and performance status ≤2) were randomized to 1250 mg/m2 Cap (days 1 to 14) and a loading dose of 1125 mg Enz on day 1 of Cycle 1 preceding daily 500 mg Enz (Cap-E) or daily placebo (Cap-P) as continuous oral 21-day cycle treatment. Pts discontinued due to progression, death, or adverse event (AE). Response was assessed before alternate cycles. The primary endpoint, progression-free survival (PFS), was compared between arms using log-rank test. Planned enrollment of 60 pts/study arm provided 80% power to detect a 40% PFS improvement with Cap-E over Cap-P (1-sided type-I error=0.20). Results: Prespecified efficacy and safety conditions were not met in a planned interim analysis and the study was terminated. All data from study enrollment to termination were analyzed. 85 pts were randomized (...

We studied tracheal intubating conditions in 120 healthy children, aged 3-12 years, in a blinded, randomised clinical trial. Children were randomly allocated to one of three groups: group PS, propofol 3 mg.kg-1 and succinylcholine 1 mg.kg-1 (n = 40); group PA, propofol 3 mg.kg-1 and alfentanil 10 microg.kg-1 (n = 40); group SF, sevoflurane 8% in 60% nitrous oxide in oxygen for 3 min (n = 40). Tracheal intubating conditions were graded according to ease of laryngoscopy, position of vocal cords, coughing, jaw relaxation and movement of limbs. Overall intubating conditions were acceptable in 39 of 40 children in the propofol/succinylcholine group, 21 of 40 children in the propofol/alfentanil group and 35 of 40 children in the sevoflurane group. Children receiving propofol and succinylcholine or sevoflurane had better intubating conditions overall than those given propofol and alfentanil (p < 0.01). In conclusion, anaesthetic induction and tracheal intubation using sevoflurane 8% for 3 min is a satisfactory alternative to propofol with succinylcholine in children.

This report presents near-minimax rational approximations for the Bessel functions J 0 ( x ) {J_0}(x) , J 1 ( x ) {J_1}(x) , Y 0 ( x ) {Y_0}(x) , and Y 1 ( x ) {Y_1}(x) for the complete range of x, with relative errors ranging down to 10 − 23 {10^{ - 23}} . The first thirty zeros of each function are listed to 35D. The tabulated zeros and the McMahon asymptotic formulae may be used to construct an algorithm which retains relative accuracy in the neighborhood of zeros.

This report presents near-minimax rational approximations for the inverse of the error function inverf x, for 0 ⩽ x ⩽ 1 − 10 − 10000 0 \leqslant x \leqslant 1 - {10^{ - 10000}} , with relative errors ranging down to 10 − 23 {10^{ - 23}} . An asymptotic formula for the region x → 1 x \to 1 is also given.

This report presents near-minimax rational approximations for the Bickley functions K i 1 ( x ) K{i_1}(x) for x ⩾ 0 , K i 2 ( x ) x \geqslant 0, K{i_2}(x) and K i 3 ( x ) K{i_3}(x) for 0 ⩽ x ⩽ 6 0 \leqslant x \leqslant 6 , and K i 8 ( x ) K{i_8}(x) , K i 9 ( x ) K{i_9}(x) and K i 10 ( x ) K{i_{10}}(x) for x ⩾ 6 x \geqslant 6 , with relative errors ranging down to 10 − 23 {10^{ - 23}} . The approximations, combined with the recurrence relation, yield a stable method of computing K i n ( x ) K{i_n}(x) , n = 1 , 2 , … , 10 n = 1,2, \ldots ,10 , for the complete range of the argument.

Some solutions of the differential equations, which describe an elementary model of the disposition of material carried by a fluid flowing in a pipe, are derived and investigated. The solutions pertain to a variety of assumptions made regarding the initial concentrations of the material in the fluid within the pipe and on the pipe interior surface, and the concentration of the material in the fluid entering the pipe. The means of obtaining some of the model parameters using the derived solutions and measured values of the concentrations of matter on the pipe surface and in the fluid are illustrated.

The problem of determining the deformation of an elastic rod of finite dimensions under a symmetrical axial loading is reduced to the solution of an infinite system of simultaneous linear equations. An approximate numerical solution is obtained for the case when the load acts uniformly over an outer annular region of the end face, and it is shown that the maximum radial displacement increases as the width of the annulus decreases. The application of the results to the problem of circumferential ridging of nuclear reactor fuel elements is discussed. It is concluded that the compression between adjacent rods probably contributes to ridge formation, but that the magnitude of the contribution cannot be determined without a knowledge of the compressive plastic stress-strain characteristics of the material.

The differential cross sections of the ${\mathrm{Be}}^{9}({\mathrm{Li}}^{6}, \ensuremath{\alpha}){\mathrm{B}}^{11}$ reaction have been measured as a function of energy and angle. The $\ensuremath{\alpha}$ particles leaving the ${\mathrm{B}}^{11}$ in the ground state, ${\ensuremath{\alpha}}_{0}$, in the first excited state, ${\ensuremath{\alpha}}_{1}$, and in the second and third excited states, ${\ensuremath{\alpha}}_{2}+{\ensuremath{\alpha}}_{3}$, were observed at 10\ifmmode^\circ\else\textdegree\fi{} intervals from 10\ifmmode^\circ\else\textdegree\fi{} to 160\ifmmode^\circ\else\textdegree\fi{} (lab system) at ${\mathrm{Li}}^{6}$ energies of 3.00, 3.25, and 3.50 Mev, and at 20\ifmmode^\circ\else\textdegree\fi{}, 60\ifmmode^\circ\else\textdegree\fi{}, 90\ifmmode^\circ\else\textdegree\fi{}, 120\ifmmode^\circ\else\textdegree\fi{}, and 160\ifmmode^\circ\else\textdegree\fi{} (c.m. system) at ${\mathrm{Li}}^{6}$ energies of 2.00, 2.50, 3.75, and 4.00 Mev. The angular distributions of the ${\ensuremath{\alpha}}_{0}$ and ${\ensuremath{\alpha}}_{1}$ groups are asymmetric about 90\ifmmode^\circ\else\textdegree\fi{} c.m. Relative maxima occur at both large and small angles for each of the $\ensuremath{\alpha}$-particle groups, with the yields at large angles being comparable to those at small angles. In all cases the angular distribution varies slowly with bombarding energy and the yields at each angle increase monotonically with increasing energy. At 3.50 Mev the total cross sections are 0.97\ifmmode\pm\else\textpm\fi{}0.38 mb for ${\ensuremath{\alpha}}_{0}$ and 0.65\ifmmode\pm\else\textpm\fi{}0.26 mb for ${\ensuremath{\alpha}}_{1}$. The experimental results suggest that the reactions proceed mainly by direct-interaction mechanisms. The similarity of the angular distributions of the ${\mathrm{Be}}^{9}({\mathrm{Li}}^{6}, \ensuremath{\alpha}){\mathrm{B}}^{11}$ and the ${\mathrm{Be}}^{9}({\mathrm{He}}^{3}, p){\mathrm{B}}^{11}$ reactions is pointed out.

The angular distribution of the $\ensuremath{\alpha}$ particles from the ${\mathrm{O}}^{18}(p, \ensuremath{\alpha}){\mathrm{N}}^{15}$ reaction and the total cross section for the ${\mathrm{O}}^{18}(p, n){\mathrm{F}}^{18}$ reaction have been measured for proton energies between 2.60 and 2.97 Mev. Comparison of the total cross sections for the two reactions eliminates the previously observed differences in resonance energies in these reactions. At most energies the $\ensuremath{\alpha}$ particles are preferentially emitted in the forward and backward directions and the angular distributions are rapid functions of proton energy.

>Absolute differential cross sections are presented for the reactions C/ sup 12/(Li/sup 6/,p)O/sup 17/ (ground state and first three excited states) and C/ sup 12/(Li/sup 6/,d)O/sup 16/ (ground state), for laboratory energies from 3.4 to 4.0 Mev. Total cross sections are about 1 mb at 4.0 Mev. Fluctuations in the angular distributions and total cross sections suggest that the reactions proceed via the compound nucleus F/sup 18/ which is excited to the region of overlapping levels. This is in contrast to the predominantly direct character of the previously studied reaction C/sup 12/(Li/sup 6/, alpha )N/sup 14/. (auth)

The time‐dependent partial differential equation governing the two‐dimensional driven diffusion in a cylindrical rod is solved analytically with an exchange strength at the surface that is either (i) proportional to the local surface concentration, or (ii) a constant. Both solutions are in the form of infinite series containing Bessel functions. Results from these calculations can be used to determine various thermodynamic properties of a solute in a homogeneous solid solution.

This note is intended formulate and prove a theorem about shear (S) waves in a transversely isotropic medium for which we have found no reference in the literature. The theorem states the following: SH waves emanating from a point source in a homogeneous transversely isotropic medium are reflected from a planar interface between the transversely isotropic medium and another homogeneous medium in such a way that they define a reflective image that is free of aberrations, regardless of the relative orientation of the elastic symmetry axis and the interface. It is an image for rays in the direction of the group velocity vectors, not the slowness vectors. The image is located on a line through the source point in the direction of the group velocity of a wave for which the slowness vector is perpendicular to the interface. The distance, measured along this line, of the image behind the interface is equal to that of the source point in front. An analogous theorem for slowness vectors exists only for isotropic media, where it is trivial and coincides with the above.

Differential cross sections were measured for the reaction /sup 13/C(/ sup 6/Li, alpha )/sup 15/N with the residual nucleus in its ground and first two excited states, the bombarding energy ranging from 3.4 to 4.0 Mev. General features suggest a direct inte raction. (auth)

This note presents nearly-best rational approximations for the functions Io(x) and 11(x), with relative errors ranging down to 10-23. The most useful set of approximations for In(x) for n = 0, 1 are the Chebyshev series expansions given in [1] and [2]. The expansions in [1] apply to the functions In(x)/xx for the range jxj ? 8 and to the functions (27rx)' /2e-In(x) for the range x > 8. The advantage of these expansions is that they can be truncated to give nearminimax approximations of arbitrary accuracy. However, they suffer from two minor defects, namely a loss of two digits of precision by cancellation for small values of x, and a lack of balance in the amount of computation required in the two ranges. For example, to compute 14S approximations, we need 15 terms of the series for Ixj 8. Shortening the lower range reduces the amount of cancellation [3], but increases the imbalance. If we use rational function approximations and minimize the relative error, we find that we can reduce the cancellation and still increase the lower range, thereby obtaining a better balance. Other rational function approximations for I0(x) and Il(x) are given in [4]. They are limited to nine or ten digits of accuracy and, since they minimize the absolute error, are less efficient than those presented here. A number of rational approximations are also given in [5], but they only apply to the range jxj 15.0, for n = 0, 1, where Rim(x) are rational functions of degree I in the numerator and m in the denominator. The details of the approximations are given in the tables that appear in the microfiche section of this issue. The format is similar to that used in [6]. Tables I to IV summarize the best approximations in the L : Walsh arrays of the functions, and Tables V to XXV give the coefficients of selected approximations. The precision is defined as Received January 26, 1973. AMS (MOS) subject classifications (1970). Primary 65D20; Secondary 33A40, 41A50.

Near-maximax rational approximations are presented for the Bickley functions Ki/sub 1/(x) for x greater than or equal to 0, Ki/sub 2/(x) and Ki/sub 3/(x) for 0 less than or equal to x less than or equal to 6, and Ki/sub 8/(x), Ki/sub 9/(x), and Ki/sub 10/(x) for x greater than or equal to 6, with relative errors ranging down to 10/sup -23/. The approximations, combined with the recurrence relation, yield a stable method of computing Ki/sub n/(x), n = 1, 2, ..., 10, for the complete range of the argument. 245 tables.

This report presents near-minimax rational approximations for the Bessel functions Jo(x), J1(x), Yo(x), and Y1(x) for the complete range of x, with relative errors ranging down to 10-23. The first thirty zeros of each function are listed to 35D. The tabulated zeros and the McMahon asymptotic formulae may be used to construct an algorithm which retains relative accuracy in the neighborhood of zeros.