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We present the results of a recent, extensive measurement campaign validating the traceability of the solar irradiance record and Earth radiation budget data. The campaign also established future traceability, thus ensuring confidence in the continuing climate-data record. The total solar irradiance radiometer facility (TRF) at the Laboratory for Atmospheric and Space Physics (LASP) Boulder, uses a liquid helium cooled cryogenic radiometer as the reference standard for the validation of spaceflight total solar irradiance (TSI) instrumentation. In 2008 the radiometer was directly compared to the National Institute of Standards and Technology (NIST) Primary Optical Watt Radiometer (POWR) at a wavelength of 532.12 nm. At TSI power levels, a correction factor of 1.000 306 with an associated standard uncertainty (u) of 0.000 098, was reported for the TRF radiometer scale when using external voltage measurement electronics, and not correcting for cavity heating non-equivalence or cavity absorptance. The TRF radiometer has recently been revalidated at LASP using a POWR calibrated silicon photodiode trap transfer standard named TT4. We report a correction factor of 0.999 787, u = 0.000 285 to align the TRF radiometer scale with the current NIST POWR scale. A new room temperature reference standard radiometer was established. It measured 133 parts per million (ppm) higher than POWR using the same silicon transfer standard as above, and in a separate direct measurement, 168 ppm lower than the TRF radiometer shuttered at 400 s full shutter cycle. The difference agrees within stated uncertainties. A correction of 0.999 867, u = 0.000 247 will align the new radiometer scale with the NIST radiant power scale of POWR.

We have developed generalized methods for electrical substitution optical measurements, as well as cryogenic detectors which can be used to implement them. The new methods detailed here enable measurement of arbitrary periodic waveforms by an electrical substitution radiometer (ESR), which means that spectral and dynamic optical power can be absolutely calibrated directly by a primary standard detector. Cryogenic ESRs are not often used directly by researchers for optical calibrations due to their slow response times and cumbersome operation. We describe two types of ESRs with fast response times, including newly developed cryogenic bolometers with carbon nanotube absorbers, which are manufacturable by standard microfabrication techniques. These detectors have response times near 10 ms, spectral coverage from the ultraviolet to far-infrared, and are ideal for use with generalized electrical substitution. In our first tests of the generalized electrical substitution method with FTS, we have achieved uncertainty in detector response of 0.13% (k = 1) and total measurement uncertainty of 1.1% (k = 1) in the mid-infrared for spectral detector responsivity calibrations. The generalized method and fast detectors greatly expand the range of optical power calibrations which can be made using a wideband primary standard detector, which can shorten calibration chains and improve uncertainties.

Capital and cost of capital form a bridge between the insurance firm and the financial markets. The term capital is used in various ways. In current parlance, economic capital is frequently used to mean capital calculated using a risk-based measure which is independent of the regulatory requirements. In this paper we discuss the concept of target capital, where the firm takes account of three different approaches to risk appetite: regulatory capital plus a buffer; rating agency views; and the views of shareholders, where they make commitments to customers and wish to protect franchise value. We describe how, when blending these views, the firm needs to understand the trade-offs between too high and too low amounts of capital, with reference to the double taxation burden, insurance gearing (leverage of premiums to capital ratio), and the impact of the firm's credit rating on maximising franchise value. We then discuss the main drivers of the cost of capital, which we define as the required total return on the market value of the firm, as determined by reference to the opportunity cost of alternative investments of equivalent risk. We explain that, because the stock market value of the firm is not the same as the capital held inside the firm, the cost of capital derived from external studies cannot be directly applied to internal measures of target return such as return on equity (ROE); it is necessary to translate between the two measures. We separate the risk of the firm between the investment risk and the insurance risk. We describe the frictional costs of investing in an insurance firm, and explain the role of parameter and model risk arising from the uncertainty of the future claim costs of the firm. We describe the findings of two studies of the actual historical stock market returns of United States P&C companies. One of them suggests that applying the Fama-French model produces higher and more accurate cost of capital estimates than the capital asset pricing model (CAPM) method. This is explained by linking the price to book ratio to the costs of financial distress, which are particularly important for general insurance firms, given the influence of insurance strength ratings from the rating agencies. Finally, we attempt to estimate the risk load required in premiums to compensate investors for the elements of cost of capital which we have described, in a way that combines the financial economic approaches to insurance target returns with the traditional actuarial approaches to assessing the risks in the insurance business.

The International Accounting Standards Board is undertaking a project to develop an Accounting Standard for Insurance. The basis for these proposals is that assets and liabilities should be shown at fair values (market values for quoted instruments). This is an updated version of a paper, prepared by a Working Party established by the General Insurance Research Organisation (GIRO) of the General Insurance Board of the actuarial profession of the United Kingdom, which was first presented to the GIRO Conference in October 2002. This paper summarises and comments upon the principal features of the proposals as they have emerged up to February 2003. The paper considers the implications for general insurance companies of these proposals. In particular, it examines the concept of market value margins, and the practical issues that insurance companies are likely to encounter in implementing them. The emphasis of the paper is on reporting for general insurance business, although many of the principles apply equally to life assurance.

The United Kingdom Ministry of Defence commissioned work to define the relationship between the internal pressure of a distressed submarine (DISSUB), the depth from which escape is made and the risk of decompression illness (DCI). The program of work used an animal model (goat) to define these risks and this paper reports the incidence and type of DCI observed. A total of 748 pressure exposures comprising saturation only, escape only or saturation followed by escape were conducted in the submarine escape simulator between 1993 and 2006. The DCI following saturation exposures was predominantly limb pain, whereas following escape exposures the DCI predominantly involved the central nervous system and was fast in onset. There was no strong relationship between the risk of DCI and the range of escape depths investigated. The risk of DCI incurred from escape following saturation was greater than that obtained by combining the risks for the independent saturation only, and escape only, exposures. The output from this program of work has led to improved advice on the safety of submarine escape.

Individual variation in physiological responsiveness to stress mediates risk for mental illness and is influenced by both experiential and genetic factors. Common polymorphisms in the human gene for FK506 binding protein 5 (FKBP5), which is involved in transcriptional regulation of the hypothalamic-pituitary-adrenal (HPA) axis, have been shown to interact with childhood abuse and trauma to predict stress-related psychopathology. In the current study, we examined if such gene-environment interaction effects may be related to variability in the threat-related reactivity of the amygdala, which plays a critical role in mediating physiological and behavioral adaptations to stress including modulation of the HPA axis. To this end, 139 healthy Caucasian youth completed a blood oxygen level-dependent functional magnetic resonance imaging probe of amygdala reactivity and self-report assessments of emotional neglect (EN) and other forms of maltreatment. These individuals were genotyped for 6 FKBP5 polymorphisms (rs7748266, rs1360780, rs9296158, rs3800373, rs9470080 and rs9394309) previously associated with psychopathology and/or HPA axis function. Interactions between each SNP and EN emerged such that risk alleles predicted relatively increased dorsal amygdala reactivity in the context of higher EN, even after correcting for multiple testing. Two different haplotype analyses confirmed this relationship as haplotypes with risk alleles also exhibited increased amygdala reactivity in the context of higher EN. Our results suggest that increased threat-related amygdala reactivity may represent a mechanism linking psychopathology to interactions between common genetic variants affecting HPA axis function and childhood trauma.

This paper seeks to define and explain financial reinsurance, a type of reinsurance growing rapidly in the general insurance market. It provides criteria for underwriters and actuaries to understand the degree of risk transfer involved and the limitations on that risk transfer. It seeks to set out criteria, applicable to both insurer and reinsurer, for estimating reserves where financial reinsurance covers are involved and for compliance with supervisory requirements. Several examples are given of typical financial reinsurance contracts currently in use.

We have carried out high resolution spatial measurements of the surface reflectance and responsivity of single and trap-configured silicon photodiodes at laser wavelengths between 325 nm and 780 nm. The results indicate that the spatial nonuniformity of quantum efficiency for a given photodiode varies with laser wavelength and internal structure. For radiometric quality diodes this nonuniformity of response leads to uncertainties in detector measurements which can be reduced to 0,03% or better.

The spiny plunder-fish, Harpagifer antarcticus, is a common shallow-water demersal species distributed along the southern limb of the Scotia Arc. A year round study was made of its reproductive biology at Signy Island, South Orkney Islands, for comparison with populations from the Antarctic Peninsula and with H. georgianus at South Georgia. Adult H. antarcticus inhabit rubble substrata and spawn 300–1500 eggs into a nest during May/July. The nest is guarded by both male and female fish during an incubation period of up to 150 days. After hatching during November/December the larvae grow at a rate of 0.082 mm d−1 (summer), 0.049 mm d−1 (winter) and 0.067 mm d−1 (annual), calculated from a time-series of samples collected from the field. This rate of growth is slow even among Antarctic species but is similar to the closely related species H. georgianus. Adult male and female H. antarcticus at the South Orkney Islands attain a maximum standard length of 88 mm and 85 mm respectively.

Samples of the squid Martialia hyadesi were collected aboard two Japanese squid-jigging vessels carrying out commercial fishing trials at the Antarctic Polar Frontal Zone, north Scotia Sea, in February 1989. The dissected stomachs of 61 specimens were classified according to fullness and the contents were examined visually. Identifiable food items included fish sagittal otoliths, crustacean eyes, the lappets on euphausiid first antennule segments and cephalopod sucker rings. The most frequent items in the squid's diet were the myctophid fishes Krefftichthys anderssoni and Electrona carlsbergi, the euphausiid Euphausia superba and a hyperiid amphipod, probably Themisto gaudichaudi. A small proportion of the sample had been feeding cannibalistically. Total lengths of the fish prey were estimated from sagittal otolith size using published relationships. All fish were relatively small; 7 to 35% of squid mantle-length. However, it is possible that some heads of larger fish are discarded by the squid and so are not represented by otoliths in the stomach contents. Over the size range of squid in the sample there was no relationship between size of fish prey and size of squid. Similarly, when the squid sample was divided into groups according to prey categories: crustaceans, crustaceans+fish, fish, cephalopod, there was no evidence that dietary preference was related to squid size. The prevalence of copepod-feeding myctophids in the diet of this squid, which is itself a major prey item of some higher predators in the Scotia Sea, suggests that a previously unrecognised food chain: copepod-myctophid-M. hyadesi-higher predator, may be an important component of the Antarctic oceanic ecosystem.

Chemokines are involved in the migration of leukocytes and have been implicated in several inflammatory diseases of the central nervous system. Some of their receptors have been proposed to mediate HIV infection.To determine changes in chemokine and receptor expression in HIV encephalitis, and to determine whether upregulation leads to recruitment of infected monocytes across the blood-brain barrier and participates in HIV neuropathology.Immunocytochemistry and double-label immunofluorescent laser confocal microscopy was performed with antibodies to chemokines and their receptors on brain tissues from patients who died with or without HIV encephalitis. In vivo distribution was compared with in vitro cultures of human neuroglial cells.The beta-chemokines monocyte chemotactic protein-1, macrophage inflammatory protein-1alpha, and RANTES were detected on brain macrophages. Their presence was associated with the histopathological signs of HIV encephalitis. The alpha-chemokines IP-10 (10 kDa inflammatory protein) and interleukin-8 were expressed by astrocytes in all tissues, including controls. Presence of the CXC-chemokine receptor (CXCR)-4 was seen on brain macrophages/microglia, neurons, and astrocytes. CC-Chemokine receptor (CCR)-5 was detected only on macrophages/microglia. CCR-3 and CCR-1 were expressed by macrophages and endothelial cells. In vitro studies examining the presence of CCR-3, CCR-5, and CXCR-4 on human brain cell cultures demonstrated abundant neuronal and microglial expression.Expression of a variety of chemokines and receptors was shown to be increased in HIV encephalitis brain tissues particularly in areas of neuroglial reaction. The expression pattern supported their involvement in the recruitment of inflammatory infiltrates and formation of microglial nodules. Presence of chemokine receptors on neurons may be involved in the pathogenesis of neurologic damage in AIDS patients.

The spatial variations of surface reflectance and response of a number of silicon photodiodes has been measured at wavelengths between 325 nm and 633 nm using a measurement spot size (1/e2) of approximately 50 micrometers . The surface reflectances have been modelled using ellipsometrically determined SiO2 layer thicknesses and compared with spectrophotometric measurements. Also the reflectance variations across the diode surface have been correlated with the response variations to give a measured of the spatial internal quantum efficiency uniformity for each photodiode.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The determination of age is an essential component in understanding the life history of fish, and is important in the assessment of the population dynamics of species to provide the data necessary to enable effective conservation and fisheries management.

We propose the use of metal-insulator films as neutral density filters for spectrophotometric calibration in the UV and visible ranges. We present a theoretical approach to the design of such filters and show that the correct selection of starting metallic material as well as filling fraction and filter thickness is important in obtaining the required profile. A comparison between theoretical and experimental Ni/SiO(2) films show the suitability of this approach to designing neutral density filters for the 200-800-nm wavelength range and beyond.

In this paper we present results from experiments to determine the behavior of C3F8‐Ar mixtures as filling gases in a uniform‐field spark gap subjected to high voltage, nanosecond pulses. The gas pressure ranges from 500 to 960 Torr and the overvoltage ranges from 50% to 300%. The electrode separation is 1 cm. U‐V irradiation has been used prior to the arrival of the pulse to the gap. In general, the discharge consists of very large numbers of closely packed filaments with the overall diameter being less than or equal to approximately 1 cm. The initial rate of current rise at the load is large (∼1012 A/sec). Subsequently, a phase of relatively constant current is observed the length of which changes with the concentration of C3F8. This phase has large resistance and the energy deposited into the discharge ranges from 6% to 20% of the energy in the incident pulse, as the concentration of C3F8 increased from 30% to 100%. The final state of conduction of the discharge is an arc. In light of these observation...

The distribution and ultrastructure of muscle-fibre types has been investigated in adult and juvenile specimens of the pelagic high-antarctic silverfish Pleuragramma antarcticum Boulenger, 1902 collected from the South Shetland Islands during the winter of 1984/1985. Two main fibre-types were identified in araldite-embedded material. The axial musculature was mainly composed of poorly vascularised, largediameter muscle fibres which were densely packed with myofibrils (volume density 81 and 72% for adults and juveniles, respectively). These ultrastructural characteristics are typical of fast-twitch fibres. The number of capillaries ner unit cross-sectional area and the volume density of mito

The hardening mechanisms in age-hardening ferritic Fe-Ni-Al-Ti alloys have been investigated using electron microscopy, tensile testing and the application of quantitative theories of strengthening in two phase materials. The level of the strength and its dependence upon aging time have been quantitatively predicted from a model in which the effects of coherency strains, modulii differences between matrix and precipitate and antiphase boundary energy are combined. Two characteristic levels of particle strength are derived in the model from the combination of these effects. The flow stress in the alloy is then determined by the stress to pass through the random array of particles in which two levels of strength exist.

Two-dimensional polyacrylamide gel electrophoresis and the radioligand (-)-[125I]iodopindolol (125I-Pin) have been used to study isoproterenol-dependent protein phosphorylation and beta-adrenergic receptor availability, respectively, in cultured Sertoli cells and freshly isolated seminiferous tubular segments of sexually immature and mature rats. Sertoli cells prepared from sexually immature rats show progressive 125I-Pin binding in primary cultures that correlates with isoproterenol-induced cell shape changes, redistribution of immunoreactive vimentin, and phosphorylation of this intermediate filament protein. The development of 125I-Pin binding to Sertoli cell lysates is blocked by cycloheximide. Seminiferous tubules do not show significant isoproterenol-dependent vimentin phosphorylation nor 125I-Pin binding. However, vimentin phosphorylation can be induced by follicle-stimulating hormone or a cyclic nucleotide analog. This study stresses the need for correlating pharmacological-induced responses observed in Sertoli cell primary cultures with those in the intact seminiferous tubule.

Acidic epididymal glycoprotein (AEG) and androgen-binding protein (ABP) antisera were used to study functional activities of primary cell cultures of the epididymal epithelium of 20--23-day-old rats. Extensive AEG immunoreactivity was associated with almost all epithelial cells of the distal caput, corpus and cauda epididymidis. ABP immunoreactivity was solely confined to some epithelial cells of the caput epididymidis. AEG and ABP immunoreactive cells were identified as principal cells. Morphological studies of enzymically dispersed aggregates of the epididymal epithelial cells showed that stromal cells were satisfactorily removed and that cell aggregates consisted of a predominant population for cells displaying the morphological characteristics of principal cells. Scanning and transmission electron microscopic studies of cultured epididymal epithelial cells in monolayers demonstrated that microvilli and pit-like invaginations of the cell surface were preserved during the first 7--10 days of culture and then gradually disappeared. Other characteristic subcellular structures such as Golgi apparatus and rough endoplasmic reticulum cisterna were preserved. Electrophoretic analysis of [35S]methionine-labelled secretory polypeptides released by epididymal epithelial cells into the culture medium demonstrated a distinct protein band pattern which differed from that observed in the medium of cultured rat Sertoli cells. These results demonstrate that primary cultures of epididymal epithelial cells isolated from sexually immature rats maintain several differentiated characteristics of the intact organ and therefore provide a valuable system for the study of epididymal epithelial cell function.

Seven proteases assumed to be aminopeptidases A, B and M, dipeptidyl peptidases II and IV, esteroproteinase and gamma-glutamyltransferase were localized histochemically, using semipermeable membrane simultaneous coupling techniques, in unfixed cryostat sections of skeletal muscle removed from one healthy volunteer, six patients with disuse muscle atrophy, and 15 patients with some form of muscle disease. Normal muscle fibres showed weak reactions for aminopeptidases A and M and for the dipeptidyl peptidases, but no reactivity for gamma-glutamyltransferase or esteroproteinase. No change was detected in diseased muscle fibres except that low gamma-glutamyltransferase and esteroproteinase activities appeared in some cases. The activities of the seven enzymes were stronger in the intermyosial connective tissue than in the muscle fibres, but were also unchanged in disease. The strongest reactions were found in some interstitial cells (mast cells and macrophages) and these were much increased in diseased muscle, particularly for dipeptidyl peptidases II and IV. The findings are interpreted in terms of the release of proteases from such cells and their subsequent involvement in the breakdown of myofibrillar proteins in muscle disease.

We have measured vibrationally resolved fluorescence from SiF+4(D 2A1) photoions to determine the vibrational branching ratio σ[v=(1,0,0,0)]/σ[v=(0,0,0,0)] in the excitation energy range 22

On the basis of simple theoretical considerations it is expected that short-lived positron emitters should be produced in fluorine, sodium, and magnesium under bombardment with 6-Mev protons. These activities have been found and ascribed to ${\mathrm{Ne}}^{19}$, ${\mathrm{Mg}}^{23}$, and ${\mathrm{Al}}^{25,\phantom{\rule{0ex}{0ex}}26}$. Half-lives, positron spectra and threshold investigations have been made and found to compare very well with the theory. It is concluded that for isobars of the type $(n\ensuremath{-}p)=\ifmmode\pm\else\textpm\fi{}1$ the difference in binding energy is due solely to the effect of Coulomb forces up to at least mass number 25. The half-lives are found to depend on the inverse fifth power of the upper limit of the positron spectra in agreement with the theory.

The generation of experimental metabolic alkalosis by the kidney was found to require the presence of excess mineralocorticoid hormone and potassium deficiency. Once generated, metabolic alkalosis could be maintained in the absence of excess mineralocorticoid, provided a strong stimulus (extracellular volume contraction or potassium deficiency or both) to proximal reabsorption was present. When proximal reabsorption was not markedly stimulated, metabolic alkalosis was corrected on reduction or discontinuance of mineralocorticoid; under these circumstances correction of potassium deficiency also corrected metabolic alkalosis. The development of metabolic alkalosis by the kidney requires accelerated distal tubular Na for H exchange. This mechanism may also maintain metabolic alkalosis as may increase proximal H + secretion.

Absorption curves for neutrons and γ‐radiation produced by 16‐Mev protons on beryllium are measured in absorber blocks of various concrete mixtures to obtain information on their shielding properties. It is shown that a mixture of cement, scrap iron, and limonite ore is as efficient as water in slowing down and capturing neutrons and, in addition, has sufficient density (ρ=3.5 g/cm3) to be an effective absorber for γ‐radiation. Compared to ordinary concrete, a three‐foot wall of iron and limonite concrete is superior by a factor of 280 for neutrons and by a factor of 20 for γ‐radiation. Boron is shown to be of little value in this type of shielding. Mechanical properties of the scrap iron‐limonite concrete are satisfactory for structural purposes. From the practical cost standpoint, a concrete made entirely of limonite ore is shown to be a reasonable compromise.

Four nuclei of the type discussed by Wigner, containing one more proton than neutron, have been produced. The nuclei, their half-lives and positron energies are: ${\mathrm{P}}^{29}$, 4.6 seconds, 3.63 Mev; ${S}^{31}$, 3.2 seconds, 3.85 Mev; ${\mathrm{Cl}}^{33}$, 2.4 seconds, 4.13 Mev; and ${\mathrm{A}}^{35}$, 2.2 seconds, 4.38 Mev. These energies are in excellent agreement with the calculated values and indicate that (1) the $\ensuremath{\pi}\ensuremath{-}\ensuremath{\pi}$ force is equal to the $\ensuremath{\nu}\ensuremath{-}\ensuremath{\nu}$ force plus the Coulomb repulsion, (2) the nuclear volumes are proportional to the atomic weights, and (3) the nuclear charge is distributed uniformly through the volume. The half-life-energy relation is in good agreement with the Fermi theory. Deviations are in the direction anticipated by the Gamow-Teller modification.

Modifications to the Princeton Particle Accelerator (PPA) such as pulsed heavy ion source, extended range radiofrequency system, vacuum system improvements, allowed the adaptation of the 3 GeV proton synchrotron to the acceleration of heavier ions. Accele ation of nitrogen ions in a charge state of N5+ and N6+ to an energy of 4 and 7 GeV were achieved starting in July 1971. Present average intensities run at about 3 x 105 and 2 x 105 particles/sec. Expectations for acceleration of neon and argon in the near future will be discussed.

The differential cross section for the scattering of 18.2\ifmmode\pm\else\textpm\fi{}0.2-Mev protons by hydrogen has been measured over the angular range 30\ifmmode^\circ\else\textdegree\fi{}-90\ifmmode^\circ\else\textdegree\fi{} in the center-of-mass system. In order to reduce the over-all errors to less than 1 percent a 60-in. scattering chamber was used. Polyethylene, polystyrene, and nylon foils were used as scatterers while the proton-proton events were detected by observing coincidences between the scattered and recoil protons in anthracene photomultiplier counters. The incident proton beam was collimated to \ifmmode\pm\else\textpm\fi{}14 minutes of arc. Probable relative errors varied from 0.5 percent at 90\ifmmode^\circ\else\textdegree\fi{} to about 1 percent at 30\ifmmode^\circ\else\textdegree\fi{}, while the probable error in the absolute differential cross section at 90\ifmmode^\circ\else\textdegree\fi{} is estimated to be 1 percent. The data show a significant deviation from pure $S$-wave scattering and are best fitted by taking $S$-, $P$-, and $D$-wave phase shifts to be ${k}_{0}=54.1\ifmmode^\circ\else\textdegree\fi{}$, ${k}_{1}=+1.0\ifmmode^\circ\else\textdegree\fi{}$, ${k}_{2}=+0.4\ifmmode^\circ\else\textdegree\fi{}$, respectively.

Nitrogen ions in charge states N(5+) and N(6+) have been accelerated in the Princeton Particle Accelerator to 4 and 7.4 billion electron volts (Gev), respectively. An external N(5+) beam of 1 x 10(6) particles per second has been obtained and focused to a 6-millimeter-diameter spot. The N(6+) beam was about 2 x 10(5) particles per second. The total charge-changing collision cross section of N(5+) in water vapor was determined as a function of ion energy. The improvement in vacuum necessary to increase the N(5+) beam at least tenfold was calculated. The N(6+) total cross section is probably smaller than that of N(5+) at the higher energies.

Comparisons were made of the growth of the larvae of Hylotrupes bajulus (1.) in untreated Pinus sylvestris logs with growth in logs impregnated under pressure with aqueous solutions of (a) 0.01% aureomycin (chlortetracycline hydrochloride-Lederle), (b) 0.50% bactopeptone (British Drug Houses), (c) 0.01% aureomycin plus 0.50% peptone, (d) 1.00% ammonium nitrate, and with water. Following 12 months storage in an incubator the effects of the above treatments, compared with untreated controls, were as follows: (a) no significant effect on larval growth; (b) larval growth significantly increased; (c) the same as (b) (the presence of aureomycin did not, therefore, alter the effect of the peptone); (d) all larvae died at an early stage. In the logs impregnated with water, larval growth was slightly but not significantly retarded. None of the substances produced greater uniformity of larval growth.