Escape efficiency of diploid and polyploid frogs: A comparison ofOdontophrynus cultripes (2n=22) andO. americanus (4n=44)

The escape efficiency of two closely related species of frogs,Odontophrynus cultripes(2n=22) and the tetraploidO. americanus (4n=44), were compared in a shuttle box and under simulated naturalistic conditions.O. americanus was generally superior toO. cultripes, and females tended to outperform males within both species. The relative inefficiency ofO. cultripes escape behavior was examined in light of the animals' having an elaborate, passive defense mechanism in the form of well-marked venom glands. Escape efficiency was highly variable in both species. Possessing twice the amount of DNA, the tetraploid behavioral variation was paradoxically less than that of the diploid, but compatible with what has been found for morphological characters in other organisms.This research was carried out at the Instituto Butantan with the support of ongoing grants from the Brazilian CNPq, FAPESP, FEDIB, and PNUD while the first author was a visiting professor in the Departamento de Genética Humana, Instituto de Biociências, Universidade de São Paulo, under the auspices of the Programa Multinacional de Genética, Organization of American States.     

Gross efficiency of muscular work during step exercise at -15°C and 21 °C

In an effort to assess the effect of ambient temperature on the gross efficiency (Eff_g) of step exercise 12 subjects performed a modified step test either at —15 °C or 21°C ascending to three different heights (corresponding to light, moderate and heavy work), for 20 min each with a frequency of 18 steps min^-1. Heart rate (HR), rectal temperature, skin temperatures and heat flux from skin were continuously measured. Oxygen consumption was measured during the last 5 min of each step height and perceptions of thermal sensation were recorded. The results indicate that, while using conventional clothing adequate in these temperatures, Eff_g is altered in a contradictory manner. At —15°C Eff_g increased with increasing work load, whereas at 21°C it decreased when the work load increased. The highest Eff_g (heavy work at —15°C and light work at 21°C) values are reflected as rather similar rectal temperatures (37.4–37.7°C) and identical mean skin temperatures (32.8 °C) as well as the same (slightly warm) thermal sensation of the legs. At — 15 °C the lowest Eff_g in light work was probably hue to the need to warm up the muscles. At 21°C, on the contrary, the activation of heat dissipation systems was probably responsible for the lowest Eff_g in heavy work.     

Supra-maximal cycling efficiency assessed in humans by using a new protocol

This study proposed a non-invasive method to determine the gross (GE, no baseline correction), net (NE, resting metabolism as the baseline correction) and work (WE, unloaded cycling as the baseline correction) efficiencies during cycling at an intensity higher than the maximal aerobic power (MAP). Twelve male subjects performed two exercises consisting of 4 min at 50% MAP followed either by 8 min at 63% MAP or by 8 sequences of 60 s divided into 10 s at 130% MAP and 50 s at 50% MAP (i.e., 63% MAP on average). Oxygen uptake was continuously measured to calculate GE, NE and WE at 50%, 63% and 130% MAP, and the data presented as the means and standard deviations. The GE values were 18.2%, 19.1%, 22.7%, the NE values were 22.4%, 22.8%, 24.3% and the WE values were 34.2%, 31.4% and 27.2% at 50%, 63% and 130% MAP, respectively. The GE and NE increased (P<0.001) whereas the WE decreased (P<0.001) with each increment in power output. The GE was lower than the NE (P<0.001) at 50% and 63% MAP and than the WE (P<0.001) at all intensities. The NE was lower (P<0.001) than the WE at 50% and 63% MAP. These results showed that (1) efficiency index values obtained during supra-maximal exercise were consistent with previous proposals and (2) the efficiency-power output relationships were not limited to sub-maximal intensity levels but were confirmed at higher power output.     

The efficacy and efficiency of an in-vitro fertilization programme including embryo cryopreservation: a cohort study

A cohort of 485 couples starting their first in-vitro fertilization(IVF) attempt between January, 1989 and February, 1991 inclusive,were followed until June 1, 1992. A total of 1086 treatmentcycles were initiated (mean 2.2, range 1–6). Of these,235 (21.8%) cycles were cancelled, giving a total of 851 embryoreplacements (mean 1.7, range 1–5). After IVF treatment,189 women have either delivered or have an ongoing pregnancyin the second or third trimester. This gives a baby take-homerate of 17.4% per started cycle and 22.2% per embryo replacement.For 91 (18.6%) of the couples, the treatment was abandoned priorto completion of the three scheduled IVF attempts and 57 (11.7%)of these had no completed IVF cycles. In the group of coupleswith reduced sperm quality, the delivery rate was significantlylower than that of the other groups. A total of 193 women hadembryos cryopreserved in at least one IVF cycle; 124 of thesewomen started a frozen embryo replacement cycle and 88 had atleast one cycle with replacement of frozen/thawed embryos, resultingin 25 deliveries/ongoing pregnancies. Due to the Norwegian lawon assisted procreation 65 (33.7%) of the women have had theirfrozen embryos thawed and discarded after 12 months of storage.The cryopreservation programme, with the limitations of theNorwegian law, gives a 5.2% increase in the baby take-home ratefor women entering the IVF programme, an increase of 13.2% inthe number of ongoing pregnancies/deliveries and an 11.6% increasein number of children/viable fetuses. A total of 214 women havedelivered or have ongoing pregnancies in the second or thirdtrimester. This represents 44.1% of the 485 women accepted forIVF treatment, irrespective of whether they were treated ornot, and 50.0% of those couples who completed at least one IVFcycle.     

An energy balance of front crawl

With the aim of computing a complete energy balance of front crawl, the energy cost per unit distance (C= v^–1, where is the metabolic power and v is the speed) and the overall efficiency (_o=W_tot/C, where W_tot is the mechanical work per unit distance) were calculated for subjects swimming with and without fins. In aquatic locomotion W_tot is given by the sum of: (1) W_int, the internal work, which was calculated from video analysis, (2) W_d, the work to overcome hydrodynamic resistance, which was calculated from measures of active drag, and (3) W_k, calculated from measures of Froude efficiency (_F). In turn, _F=W_d/(W_d+W_k) and was calculated by modelling the arm movement as that of a paddle wheel. When swimming at speeds from 1.0 to 1.4 m s^–1, _F is about 0.5, power to overcome water resistance (active body drag × v) and power to give water kinetic energy increase from 50 to 100 W, and internal mechanical power from 10 to 30 W. In the same range of speeds increases from 600 to 1,200 W and C from 600 to 800 J m^–1. The use of fins decreases total mechanical power and C by the same amount (10–15%) so that _o (overall efficiency) is the same when swimming with or without fins [0.20 (0.03)]. The values of _o are higher than previously reported for the front crawl, essentially because of the larger values of W_tot calculated in this study. This is so because the contribution of W_int to W_tot was taken into account, and because _F was computed by also taking into account the contribution of the legs to forward propulsion.     

A comparison of three methods for titration of poliovirus vaccines

Two methods for in vitro endpoint titration of poliovirus — the roller tube and the microtitration assay — were compared with each other and with the plaque assay, using secondary vervet monkey kidney cells and Vero cells as indicators. The roller tube method is the most reliable under difficult working conditions, but is otherwise cumbersome and expensive. The microtitre method is the most economical and the plaque assay the most sensitive. By suspending freshly trypsinized indicator cells with the virus dilutions before planting, it was possible to simplify the microtitre method considerably. The sensitivity of the plaque assay was improved for Vero cells by absorbing the virus onto freshly planted monolayers. The method was scaled down to a semi-micro level by using 24-well cell culture trays. The slower rate of plaque development under a low calcium overlay medium facilitated a more accurate plaque count.     

O2 Uptake in hyperthyroidism during constant work rate and incremental exercise

Summary To investigate the effect of hyperthyroidism on the pattern and time course of O₂ uptake ( O₂) following the transition from rest to exercise, six patients and six healthy subjects performed cycle exercise at an average work rate (WR) of 18 and 20 W respectively. Cardiorespiratory variables were measured breath-by-breath. The patients also performed a progressively increasing WR test (1-min increments) to the limit of tolerance. Two patients repeated the studies when euthyroid. Resting and exercise steady-state (SS) O₂ (ml·kg^–1·min^–1) were higher in the patients than control (5.8, SD 0.9 vs 4.0, SD 0.3 and 12.1, SD 1.5 vs 10.2, SD 1.0 respectively). The increase in O₂ during the first 20 s exercise (phase I) was lower in the patients (mean 89 ml·min^–, SD 30) compared to the control (265 ml·min^–1, SD 90), while the difference in half time of the subsequent (phase 11) increase to the SS O₂ (patient 26 s, SD 8; controls 17 s, SD 8) were not significant (P = 0.06). The OZ cost per WR increment ( O₂/WR) in ml·min^–1·^–1, measured during the incremental period (mean 10.9; range 8.3–12.2), was always within two standard deviations of the normal value (10.3, SD 1). In the two patients who repeated the tests, both the increment of O₂ from rest to SS during constant WR exercise and the O₂/WRs during the progressive exercise were higher in the hyperthyroid state than during the euthyroid state. While both resting and exercise O₂ are increased in the hyperthyroid patients, the O₂ cost of a given increment of WR is within the normal range. However, a small reduction in the O₂ requirement to perform exercise following treatment of the hyperthyroid state suggests a subtle change O₂ cost of muscle work in this disease.     

Energy cost and mechanical efficiency of riding a four-wheeled, human-powered, recumbent vehicle

Oxygen consumption at steady state (V˙O ₂, l · min⁻¹) and mechanical power (W˙, W) were measured in five subjects riding a human-powered vehicle (HPV, the Karbyk, a four-wheeled recumbent cycle) on a flat concrete road at constant sub-maximal speeds. The external mechanical work spent per unit of distance (W, J · m⁻¹), as calculated from the ratio of W˙ to the speed (v, m · s⁻¹), was found to increase with the square of v: W˙=8.12+(0.262 ·v ²) (r=0.986, n=31), where the first term represents the mechanical energy wasted, over a unit of distance, against frictional forces (rolling resistance, R_r), and the second term (k · v ²) is the work performed, per unit distance, to overcome the air drag. The rolling coefficient (C_r, obtained dividing R_r by m · g, where m is the overall mass and g is the acceleration of gravity) amounted to [mean (SD)] 0.0084 (0.0008), that is about 60% higher than that of a racing bicycle. The drag coefficient was calculated from the measured values of k, air density (ρ) and frontal area (A) [C_x=k · (0.5 · A · ρ)⁻¹], and amounted to 1.067 (0.029), that is about 20% higher than that of a racing bicycle. The energy cost of riding the HPV (C_k, J · m⁻¹) was measured from the ratio of metabolic power above rest (net V˙O ₂, expressed in J · s⁻¹) to the speed (v, m · s⁻¹); the value of this parameter increased with the square of v, as described by: C_k=61.45 + (0.675 · v ²) (r=0.711, n=23). The net mechanical efficiency (η) was calculated from the ratio of W to C_k: over the investigated speed range this turned out to be 0.22 (0.021). Best performance times (BPTs) of a “typical”élite athlete riding the Karbyk were calculated over the distances of 1, 5 and 10 km: these were about 8% longer than the BPTs calculated, on the same subjects, when riding a conventional racing bicycle. Accepted: 7 August 2000     

评“McCall观察方法”——对一种色谱系统分配效果观察方法的商榷

本文通过理论分析和文献数据的分析,对McCall提出的色谱系统分配效果的观察方法提出了不同的看法,认为McCall方法中的所谓logK并不是常数。McCall的方法无论在理论上和实践上都是不妥的。     

江苏省护理院卫生资源配置现状和效率研究

目的:分析江苏省护理院卫生资源配置现状与效率,并提出完善对策。方法:应用描述性统计方法分析2013~2019年护理院卫生资源配置和利用情况,采用数据包络分析法评价卫生资源投入产出效率,采取TOPSIS法综合评估床位利用效率。结果:2019年江苏省护理院为246家,其中71.95%集中在城市地区;2019年护理院床位数为38274张,床位医生比和床位护士比分别为1:0.06和1:0.18,床位使用率为72.32%,平均住院天数比2013年缩短20.5天。数据包络分析结果显示,2016~2018年综合技术效率值均为1.0,2019年为0.990。TOPSIS法评估结果显示,2013~2017年床位利用效率逐年上升,2018和2019年有所下降。结论:护理院城乡分布不均衡,人员配置不足,近年来投入产出效率为相对有效或弱有效,但床位总体利用率偏低。今后合理规划设置护理机构,增加人力资源配置,提升护理院服务质量,最大限度发挥护理院卫生资源的作用。