Lattice charge models and core level shifts in disordered alloys.

Differences in core level binding energies between atoms belonging to the same chemical species can be related to differences in their intra- and extra-atomic charge distributions, and differences in how their core holes are screened. With this in mind, we consider the charge-excess functional model (CEFM) for net atomic charges in alloys (Bruno et al 2003 Phys. Rev. Lett. 91 166401). We begin by deriving the CEFM energy function in order to elucidate the approximations which underpin this model. We thereafter consider the particular case of the CEFM in which the strengths of the 'local interactions' within all atoms are the same. We show that for binary alloys the ground state charges of this model can be expressed in terms of charge transfer between all pairs of unlike atoms analogously to the linear charge model (Magri et al 1990 Phys. Rev. B 42 11388). Hence, the model considered is a generalization of the linear charge model for alloys containing more than two chemical species. We then determine the model's unknown 'geometric factors' over a wide range of parameter space. These quantities are linked to the nature of charge screening in the model, and we illustrate that the screening becomes increasingly universal as the strength of the local interactions is increased. We then use the model to derive analytical expressions for various physical quantities, including the Madelung energy and the disorder broadening in the core level binding energies. These expressions are applied to ternary random alloys, for which it is shown that the Madelung energy and magnitude of disorder broadening are maximized at the composition at which the two species with the largest 'electronegativity difference' are equal, while the remaining species have a vanishing concentration. This result is somewhat counterintuitive with regards to the disorder broadening since it does not correspond to the composition with the highest entropy. Finally, the model is applied to CuPd and CuZn random alloys. The model is used to deduce the effective radii associated with valence electron charge transfer for Cu, Pd and Zn in these systems for use in the 'ESCA potential model' of x-ray photoelectron spectroscopy. The effective radii are found to be R1/3, where R1 is the nearest neighbor distance, with only small variations between chemical elements and between different systems. The model provides a framework for rationalizing the disorder broadenings in these systems: they can be understood in terms of an interplay between the broadening in the Madelung potentials and the broadening in the intra-atomic electrostatic potentials.

Seed rain under tree islands planted to restore degraded lands in a tropical agricultural landscape.

Planting native tree seedlings is the predominant restoration strategy for accelerating forest succession on degraded lands. Planting tree "islands" is less costly and labor intensive than establishing larger plantations and simulates the nucleation process of succession. Assessing the role of island size in attracting seed dispersers, the potential of islands to expand through enhanced seed deposition, and the effect of planting arrangements on seed dispersal by birds and bats informs restoration design. Determining the relative importance of local restoration approach vs. landscape-level factors (amount of surrounding forest cover) helps prioritize methods and locations for restoration. We tested how three restoration approaches affect the arrival of forest seeds at 11 experimental sites spread across a gradient of surrounding forest cover in a 100-km2 area of southern Costa Rica. Each site had three 50 x 50 m treatments: (1) control (natural regeneration), (2) island (planting tree seedlings in patches of three sizes: 16 m2, 64 m2, and 144 m2), and (3) plantation (planting entire area). Four tree species were used in planting (Terminalia amazonia, Vochysia guatemalensis, Erythrina poeppigiana, and Inga edulis). Seed rain was measured for 18 months beginning approximately 2 years after planting. Plantations received the most zoochorous tree seeds (266.1 +/- 64.5 seeds x m(-2) x yr(-1) [mean +/- SE]), islands were intermediate (210.4 +/- 52.7 seeds x m(-2) x yr(-1)), and controls were lowest (87.1 +/- 13.9 seeds x m(-2) x yr(-1)). Greater tree seed deposition in the plantations was due to birds (0.51 +/- 0.18 seeds x m(-2) x d(-1)), not bats (0.07 +/- 0.03 seeds x m(-2) x d(-1)). Seed rain was primarily small-seeded, early-successional species. Large and medium islands received twice as many zoochorous tree seeds as small islands and areas away from island edges, suggesting there is a minimum island size necessary to increase seed deposition and that seed rain outside of planted areas is strongly reduced. Planting design was more important for seed deposition than amount of forest cover within the surrounding 100- and 500-m radius areas. Establishing plantations and large islands facilitates the arrival of early-successional tree seeds and represents a broadly applicable strategy for increasing seed rain on abandoned agricultural lands. However, more intensive restoration approaches may be necessary for establishment of dispersal-limited species.

Auger energy shifts in fcc AgPd random alloys from complete screening picture and experiment.

We extend the complete screening picture to ab initio calculations of Auger kinetic energy and Auger parameter shifts in metallic alloys. Experimental measurements of the L(3)M(4,5)M(4,5) Auger transition in fcc AgPd random alloys are compared with first-principles calculations and the results are in excellent agreement for both the Ag and Pd Auger shifts over the whole concentration range. We discuss the Auger kinetic energy shifts in terms of single-hole states for the 2p(3/2) core level and double-hole states for the 3d(5/2) level.

Sleep detection with an accelerometer actigraph: comparisons with polysomnography.

Two validation studies were conducted to optimize the sleep-detection algorithm of the Actillume. The first study used home recordings of postmenopausal women (age range: 51 to 77 years), which were analyzed to derive the optimal algorithm for detecting sleep and wakefulness from wrist activity data, both for nocturnal in-bed recordings and considering the entire 24 h. The second study explored the optimal algorithm to score in-bed recordings of healthy young adults (age range: 19 to 34 years) monitored in the laboratory. In Study I, the algorithm for in-bed recordings (n=39) showed a minute-by-minute agreement of 85% between Actillume and polysomnography (PSG), a correlation of.98, and a mean measurement error (ME) of 21 min for estimates of sleep duration. Using the same algorithm to score 24-h recordings with Webster's rules, an agreement of 89%, a correlation of.90, and 1 min ME were observed. A different algorithm proved optimal to score in-bed recordings (n=31) of young adults, yielding an agreement of 91%, a correlation of.92, and an ME of 5 min. The strong correlations and agreements between sleep estimates from Actillume and PSG in both studies suggest that the Actillume can reliably monitor sleep and wakefulness both in community-residing elderly and healthy young adults in the laboratory. However, different algorithms are optimal for individuals with different characteristics.

No melatonin suppression by illumination of popliteal fossae or eyelids.

A recent report that popliteal illumination shifted the circadian rhythms of body temperature and melatonin challenged the longstanding belief that light phase-shifting the circadian system in mammals is mediated only through the retina. The authors tested effects of popliteal illumination and illumination provided through the eyelids on melatonin suppression. In randomized, counterbalanced orders, healthy volunteers received three treatments from midnight until 2:00 AM, one on each of three visits to the laboratory. Treatments included (1) no illumination from light pads applied to the popliteal fossae, with light mask maintained at < 3 lux (control); (2) light mask illuminated at 1700 lux, with popliteal light pads extinguished; and (3) popliteal light pads illuminated (13,000 lux) and light mask at < 3 lux (control). Saliva specimens were sampled at midnight, at 1:00 AM, and at 2:00 AM. Mean salivary melatonin concentrations rose from an average of 30.8 (3.9) pg/ml at midnight (baseline), to 33.2 (4.0) pg/ml at 1:00 AM, and to 37.2 (3.8) pg/ml at 2:00 AM in all three conditions, but no statistical differences were found using repeated-measures ANOVA. No evidence of melatonin suppression by either popliteal or closed eyelid light stimulation was found. These data suggest that bright retinal illumination is necessary for suppression of melatonin mediated through the suprachiasmatic nuclei.

trans-resveratrol content in commercial peanuts and peanut products.

A modified high-performance liquid chromatographic (HPLC) method for determination of trans-resveratrol (resveratrol) in peanuts and peanut products has been developed. Resveratrol was extracted with acetonitrile-water (90/10, v/v) by blending with diatomaceous earth at high speed followed by purification of an aliquot of the extract on a minicolumn packed with Al(2)O(3)-ODS (C(18)) mixture. The column was eluted with acetonitrile-water (90/10, v/v), eluate was evaporated under nitrogen, and residue was dissolved in HPLC mobile phase. Resveratrol in an aliquot of purified extract was quantitated by HPLC on silica gel with n-hexane-2-propanol-water-acetonitrile-acetic acid (1050/270/17/5/1, v/v) as a mobile phase. The recovery of resveratrol added to diatomaceous earth at 0.05 microg/g was 98.95 +/- 17.79%; the recovery of the standard added to fresh peanuts (with 0.070 microg/g natural level of resveratrol) at 0.50, 5.00, and 10.00 microg/g was 117.23 +/- 8.87, 100.10 +/- 2.49, and 100.45 +/- 1.51%, respectively. The quantitation limit of resveratrol in fresh peanuts was about 0. 01 microg/g. Roasted peanuts had the lowest content of resveratrol of 0.055 +/- 0.023 microg/g (n = 21), while in peanut butter its concentration was significantly higher, 0.324 +/- 0.129 microg/g (n = 46), and boiled peanuts had the highest level of 5.138 +/- 2.849 microg/g (n = 12). Resveratrol content in commercial peanut products was similar to the resveratrol content of the raw peanut fractions routinely used for making them.

Aflatoxin reduction in corn through field application of competitive fungi.

Soil in corn plots was inoculated with nonaflatoxigenic strains of Aspergillus flavus and A. parasiticus during crop years 1994 to 1997 to determine the effect of application of the nontoxigenic strains on preharvest aflatoxin contamination of corn. Corn plots in a separate part of the field were not inoculated and served as controls. Inoculation resulted in significant increases in the total A. flavus/parasiticus soil population in treated plots, and that population was dominated by the applied strain of A. parasiticus (NRRL 21369). In the years when weather conditions favored aflatoxin contamination (1996 and 1997), corn was predominately colonized by A. flavus as opposed to A. parasiticus. In 1996, colonization by wild-type A. flavus was significantly reduced in treated plots compared with control plots, but total A. flavus/parasiticus colonization was not different between the two groups. A change to a more aggressive strain of A. flavus (NRRL 21882) as part of the biocontrol inoculum in 1997 resulted in a significantly (P < 0.001) higher colonization of corn by the applied strain. Weather conditions did not favor aflatoxin contamination in 1994 and 1995. In 1996, the aflatoxin concentration in corn from treated plots averaged 24.0 ppb, a reduction of 87% compared with the aflatoxin in control plots that averaged 188.4 ppb. In 1997, aflatoxin was reduced by 66% in treated corn (29.8 ppb) compared with control corn (87.5 ppb). Together, the data indicated that although the applied strain of A. parasiticus dominated in the soil, the nonaflatoxigenic strains of A. flavus were more responsible for the observed reductions in aflatoxin contamination. Inclusion of a nonaflatoxigenic strain of A. parasiticus in a biological control formulation for aflatoxin contamination may not be as important for airborne crops, such as corn, as for soilborne crops, such as peanuts.

Light mask 500 lux treatment for delayed sleep phase syndrome.

1. Bright light exposure has been demonstrated as an effective treatment for circadian rhythm sleep disorders. Recent studies suggest that more moderate intensities of light might affect endogenous rhythms. A light mask treatment, using light applied through eyelids during sleep, was tested for Delayed Sleep Phase Syndrome. 2. The active light group (n = 5) received 500 lux light for 3 hours prior to awakening for 12 days. The placebo light group (n = 5) received 0.1 lux light with the same timing. Circadian rhythm phase was assessed from core body temperature and urinary 6-sulfatoxymelatonin measurements. The SIGH-SAD-SR mood scale was administered to assess mood. 3. There were slight trends toward a phase advance of the body temperature rhythm and a phase delay of the melatonin rhythm, and both groups reported anti-depressant benefits. However, no statistically significant effects of 500 lux light mask treatment were demonstrated compared with the placebo-light treatment. 4. More extensive studies will be required to clarify the factors of dose-response and phase-response.

Financial planning considerations at retirement.

The process of retirement planning is a difficult one for a physician. The Planning process should address the areas of Investment Planning, Estate Planning, and Risk Management. This article examines each of these dimensions with special emphasis on Modern Portfolio Theory as the basis for investment planning.

Estimating aflatoxin in farmers' stock peanut lots by measuring aflatoxin in various peanut-grade components.

Five, 2 kg test samples were taken from each of 120 farmers' stock peanut lots contaminated with aflatoxin. Kernels from each 2 kg sample were divided into the following grade components: sound mature kernels plus sound splits (SMKSS), other kernels (OK), loose shelled kernels (LSK), and damaged kernels (DAM). Kernel mass, aflatoxin mass, and aflatoxin concentration were measured for each of the 2400 component samples. For 120 lots tested, average aflatoxin concentrations in SMKSS, OK, LSK, and DAM components were 235, 2543, 11,775, and 69,775 ng/g, respectively. Aflatoxins in SMKSS, OK, LSK, and DAM components represented 6.9, 7.9, 33.3, and 51.9% of the total aflatoxin mass, respectively. Cumulatively, 3 aflatoxin risk components--OK, LSK, and DAM--accounted for 93.1% of total aflatoxin, but only 18.4% percent of test sample mass. Correlation analysis suggests that the most accurate predictor of aflatoxin concentration in the lot is the cumulative aflatoxin mass in the high 3 risk components OK + LSK + DAM (correlation coefficient, r = 0.996). If the aflatoxin in the combined OK + LSK + DAM components is expressed in concentration units, r decreases to 0.939. Linear regression equations relating aflatoxin in OK + LSK + DAM to aflatoxin concentration in the lot were developed. The cumulative aflatoxin in the OK + LSK + DAM components was not an accurate predictor (r = 0.539) of aflatoxin in the SMKSS component. Statistical analyses of 3 other data sets published previously yielded similar results.

Displaced intra-articular fractures of the distal aspect of the radius. Long-term results in young adults after open reduction and internal fixation.

The purpose of this retrospective study was to determine the long-term functional and radiographic outcomes in a series of young adults (less than forty-five years old) in whom an acute displaced intra-articular fracture of the distal aspect of the radius had been treated with operative reduction and stabilization. Twenty-six fractures in twenty-six patients met the initial inclusion criteria for the study. Twenty-one patients returned for a physical examination, imaging (plain radiographs and computerized tomography scans), and completion of a validated musculoskeletal function assessment questionnaire at a minimum of 5.5 years. The physical examinations were performed by the same observer, who was not involved in the initial care of the patients. The plain radiographs and computerized tomography scans were assessed in a blinded fashion by two independent observers who measured the radiographic parameters with standardized methods. At an average of 7.1 years, osteoarthrosis of the radiocarpal joint was evident on the plain radiographs and computerized tomography scans of sixteen (76 per cent) of the twenty-one wrists. A strong association was found between the development of osteoarthrosis of the radiocarpal joint and residual displacement of articular fragments at the time of osseous union (p < 0.01). However, the functional status at the time of the most recent follow-up, as determined by physical examination and on the basis of the responses on the questionnaire, did not correlate with the magnitude of the residual step and gap displacement at the time of fracture-healing. All patients had a good or excellent functional outcome irrespective of radiographic evidence of osteoarthrosis of the radiocarpal or the distal radio-ulnar joint or non-union of the ulnar styloid process. It appears prudent therefore to base the indications for salvage operative procedures on the presence of severe symptoms or a loss of function rather than on radiographic evidence of osteoarthrosis of the radiocarpal joint.

Radiographic evaluation of osseous displacement following intra-articular fractures of the distal radius: reliability of plain radiography versus computed tomography.

This study evaluated the reliability of plain radiography versus computed tomography (CT) for the measurement of small (< 5 mm) intra-articular displacements of distal radius fracture fragments. The plain radiographs and CT scans of 19 acute intra-articular distal radius fractures were used by 5 independent observers, using 2 standardized techniques, to quantify incongruity of the articular surface in a blinded and randomized fashion. Repeat measurements were performed by the same observers 2-4 weeks later, allowing determination of intraclass correlation coefficients (ICC) as a measure of intraobserver and interobserver agreement. The average maximum gap displacement on plain radiographs was 2.1 mm (range, 0.0-15.0 mm, lateral view) and on CT images was 4.9 mm (range, 0.7-17.3 mm, axial view). The average maximum step displacement on plain radiographs was 0.9 mm (range, 0.0-6.4 mm, lateral view) and on CT images was 1.2 mm (range, 0.0-6.0 mm, sagittal view). More reproducible values determining step and gap displacement were obtained when the arc method of measurement was used on CT scans (ICC values, .69-.97) as compared to the longitudinal axis method for plain radiographs (ICC values, .30-.50). For measured displacements of 2 mm or more, our data demonstrated poor correlation between measurements made on CT images and those made on plain radiographs (gap or step displacement > 2 mm, K = 0.21; step displacement > 2 mm, K = 0.21). Thirty percent of measurements from plain radiographs significantly underestimated or overestimated displacement compared to CT scan measurements. From these data, we conclude that CT scanning data, using the arc method of measurement, are more reliable for quantifying articular surface incongruities of the distal radius than are plain radiography measurements.

Quantification of the radial torsion angle with computerized tomography in cadaver specimens.

Torsion of a long bone is the twist along its longitudinal axis; torsion of the radius is defined by the angle between the proximal and distal metaphyses in the transverse plane. Measurement of the radial torsion angle provides a means of detection and quantification of malrotation after a fracture. The purpose of the current study was to develop and standardize a technique for the measurement of torsion of the radius. Axial computerized tomographic images of thirty-nine pairs of dry cadaver specimens of normal radii, and an additional four pairs of radii with a unilateral deformity of the distal metaphysis that was consistent with a previous fracture, were studied and a measurement protocol was established. The radial torsion angle was measured by three independent observers on two separate occasions. Reproducibility of the technique was determined with use of the intraclass correlation coefficient to express both interobserver and intraobserver reliability. Consistency of measurements between observers and by the same observer was high, with intraclass correlation coefficients ranging from 0.87 to 0.94. The mean torsion angle for the eighty-two normal radii in the study was 32.6 degrees (95 per cent confidence interval of the mean, 30.3 to 34.9 degrees; range, 1.4 to 58.8 degrees). There were small variations in torsion angle between the two radii of each normal pair (mean side-to-side difference, 4.9 degrees; 95 per cent confidence interval of the mean, 3.5 to 6.3 degrees). The mean torsion angle of the four radii with a malunited fracture was 10.4 degrees (95 per cent confidence interval of the mean, 5.7 to 15.1 degrees), and the mean side-to-side difference in the pairs containing these radii was 24.1 degrees (95 per cent confidence interval of the mean, 8.5 to 39.6 degrees; p < 0.0001 compared with the normal radii).

Classification of ulnar deficiency according to the thumb and first web.

Fifty-five ulnar-deficient upper extremities in 45 patients treated at the St. Louis Shriner's Hospital were reviewed in order to evaluate the hand abnormalities. Thumb and first-web abnormalities were noted in 73% of hands. The majority of operations (28 of 53) were recommended to improve functional deficits associated with abnormalities of the thumb and first web. A classification of the ulnar-deficient hand based upon the characteristics of the thumb and first web is presented. When used in combination with any of the six current forearm/elbow classification schemes, this classification more completely describes ulnar deficiency of the upper extremity. Four classification types are proposed based upon progressive involvement of the thumb and first web. In type A, the thumb and first web are normal; in type B, the first web space has mild deficiency and the thumb has mild involvement. Extrinsic tendon function is intact and opposition function is present. In type C, the thumb has varying degrees of involvement. The first web has moderate to severe deficiency, including thumb-index syndactyly, and is often associated with malrotation of the thumb into the plane of the other digits, loss of opposition, and dysfunction of the extrinsic tendons. In type D, the thumb is absent. Previous classifications of ulnar deficiency neglect the radial hand anomalies that have been noted by several authors in a high percentage of affected extremities. Our premise for this classification is that the thumb and first-web abnormalities are related to the complexity of the hand problem and that the frequently noted radial hand abnormalities require the majority of surgical procedures. Such a classification based on the thumb and first-web deformities will focus the surgeon's attention on those deficiencies that are most important for the restoration of function. It is proposed that ulnar deficiency be classified by one of the classification schemes that describes the anatomy of the forearm and/or elbow supplemented by the hand classification type.

The use of routine wrist radiography in the evaluation of patients with carpal tunnel syndrome.

The objective of this study was to evaluate the use of routine wrist radiography in the evaluation of patients with carpal tunnel syndrome (CTS). In the setting of a community-based hand surgery practice, we performed a retrospective review of charts and radiographs for 300 consecutive patients (447 wrists) meeting clinical and electrophysiologic criteria for CTS. Data on all patients included information obtained by the use of medical history questionnaires, physical examinations, nerve conduction studies, and radiographs of the wrist. Abnormalities were noted in 146 of 447 wrist radiographs (33%). Eighty-three (18.6%) had abnormalities that might have been implicated in the development of CTS, although these findings would not alter management. For only 2 of 447 wrists (0.4% of wrists; 0.6% of patients) were there radiographic findings of therapeutic significance. Radiographic charges were calculated to be $5,869 to $20,115 for each finding of therapeutic significance. We conclude that wrist radiographs should not be performed routinely in patients with CTS, owing to the low yield of useful information.

Nocturnal light effects on menstrual cycle length.

OBJECTIVES: In previous University of California, San Diego (UCSD) studies, nocturnal illumination shortened menstrual cycles that were longer than 33 days. The studies reported here extend the previous findings, confining the illumination to the sleep period. DESIGN: Two light levels (235 to 250 lux and less than 1 lux) and 2 modes of light delivery (lighted sleep mask and bedside lamp) were tested. RESULTS: 235 to 250 lux treatment cycle lengths were significantly shorter than baseline, but not significantly shorter than the less than 1 lux treatment cycle lengths. Subjective reports of sleep disturbance were greater with the 235 to 250 lux treatment, but there was no significant difference in overall quality of sleep between the two light levels. CONCLUSIONS: The current data alone do not exclude spontaneous remission or suggestion, but our previous studies demonstrated significant contrasts between 235 to 250 lux and less than 1 lux light levels. This study suggests that treatment may be effective when confined to the sleep period, and that light masks, which do not disturb bed partners, may be used in place of bedside lamps.

Neuromuscular effects of toxins isolated from southern prickly ash (Zanthoxylum clava-herculis) bark.

OBJECTIVE: To define the nature and mechanisms of neuromuscular effects of toxic principles in bark of Southern Prickly Ash tree (Zanthoxylum clava-herculis) that might contribute to its clinical toxicity in cattle. ANIMALS: 31 rats, 1 dog, and 4 rabbits. PROCEDURES: Extracts were prepared from bark samples, using 2 extraction methods. Contractile responses, resting potentials, miniature end-plate potentials (MEPP), and end-plate potentials of rat phrenic nerve-hemidiaphragm preparations were recorded. Blood pressure and contractile responses of the cranial tibial muscle to nerve stimulation were recorded in an anesthetized dog. Topical anesthetic activity in rabbits was determined by evaluation of the corneal reflex. RESULTS: One extract usually stimulated muscle contractile response, whereas the other inhibited this response when evoked by nerve stimulation, but not when evoked by direct muscle stimulation. Inhibitory extract (XI) had a hypotensive effect, but lacked topical anesthetic activity and effect on resting potentials. This extract also reduced amplitude of MEPP and end-plate potentials, but did not affect their time course or the frequency of MEPP. Stimulatory extract was not active in presence of neuromuscular blocking agent tubocurarine. CONCLUSION: Active principles in Southern Prickly Ash extracts appear to exert their action on neuromuscular transmission probably through blockade of postjunctional, end-plate receptors (XI) or enhanced release of neurotransmitter (stimulatory extract). CLINICAL RELEVANCE: Signs of clinical toxicity in cattle were best correlated with effects of XI, which can be antagonized by Ca2+ and neostigmine.

Seasonal variation in human illumination exposure at two different latitudes.

The authors measured ambient illumination exposure in healthy volunteers in San Diego, California (latitude 32 degrees 43' N, n = 30), and Rochester, Minnesota (latitude 44 degrees 1' N, n = 24), during each of the four quarters of the year, which were centered on the solstices and equinoxes. Subjects wore photosensors on their wrists and lapels (or foreheads while in bed) 24 h per day for an average of 5-6 days per quarter. The maximum of the two illumination readings was stored each minute. Annual average time spent per day in outdoor illumination (> or = 1000 lux) was significantly higher in San Diego than it was in Rochester (p < .04). Daily durations of illumination at or exceeding thresholds of 1, 10, 100, 1000, and 10,000 lux were highly seasonal in the sample as a whole (p < .01 at 1 lux, p < .0001 at other thresholds). Seasonal variation in outdoor illumination was far more pronounced in Rochester than it was in San Diego (interaction p < .001) but remained significant in San Diego (p < or = .03). Seasonal variation in indoor illumination was generally similar in the two cities. The median Rochester subject experienced illumination > or = 1000 lux for 2 h 23 min per day during summer and 23 min per day during winter. The corresponding times in San Diego were 2 h 10 min and 1 h 20 min. Neither age nor gender predicted illumination duration at any level. Both season and geographic location strongly influenced human illumination exposure, and behavior (choice of indoor vs. outdoor environment) was the most important mediating factor.