Validation and Substantiation of 25 kGy as Sterilization Dose for Lyophilized Human Amnion Membrane

The validation and substantiation of sterilization dose for lyophilized human amnion membrane by gamma irradiation delivered by Co⁶⁰ source were investigated. The validation experiments were conducted according to ISO 13409 method B. A total of 120 human amnion membranes were collected. Of these, 10 membranes were used for estimation of bioburden and 20 membranes were used for the individual sterility test at verification dose. The average bioburden per product unit with sample item portion (SIP = 1) for lyophilized human amnion membrane was 572 cfu. The verification dose experiments were done at dose of 8.1 kGy and the results of sterility tests showed that human amnion membrane got one positive. Consequently, the sterilization dose of 25 kGy was confirmed and substantiated.     

On the capacity of macroparasites to control insect populations

A graphical model of the population dynamics of macroparasites and their hosts is developed. Three principal means by which the parasites can be regulated are considered: reduction in host density as a result of parasite-induced host mortality, reduction in host density as a result of parasite-induced host sterility, and competition among parasites within multiply-infected hosts. The means by which parasites are regulated has a major effect on the degree to which they can depress host population densities. In particular, a parasite that sterilizes its host is expected to reduce host density more than one that causes an equivalent decline in host fitness through increased mortality. A special case of the model is developed for herbivorous insects that, in the absence of parasites, are limited by larval food resources. Parasites that are regulated via parasite-induced host sterility will control the insect populations below the level set by larval resources if the threshold host density for the parasites (N(T)) is less than the ratio of carrying capacity to net reproductive rate of the insects (K/R). Data are presented showing that all three means of parasite regulation, but especially parasite-induced host sterility, can operate in Howardula aoronymphium, a nematode parasite of mycophagous Drosophila flies. Data from a field cage experiment show that, if these nematodes are regulated primarily via reductions in host density due to this sterility, the parameters N(T), K, and R are such that Howardula is likely to play an important role in controlling Drosophila populations. However, this conclusion must be tempered by the fact that these nematodes also cause increased host mortality and experience within-host competition, making the conditions for parasite control of the flies more stringent.     

Sampling strategies for square and boll-feeding plant bugs (Hemiptera: Miridae) occurring on cotton

Sampling methods for square and boll-feeding plant bugs (Hemiptera: Miridae) occurring on cotton, Gossypium hirsutum L., were compared with the intent to assess if one approach was viable for two species occurring from early-season squaring to late bloom in 25 fields located along the coastal cotton growing region of south Texas. Cotton fleaphopper, Pseudatomoscelis seriatus (Reuter), damages squares early-season and dominated collections using five sampling methods (approximately 99% of insects collected). A major species composition shift occurred beginning at peak bloom in coastal fields, when verde plant bug, Creontiades signatus Distant, represented 55-65% of collections. Significantly more cotton fleahoppers were captured by experienced samplers with the beat bucket and sweep net than with the other methods (30-100% more). There were more than twice as many verde plant bugs captured by experienced and inexperienced samplers with the beat bucket and sweep net than captured with the KISS and visual methods. Using a beat bucket or sweep net reduced sampling time compared with the visual method for the experienced samplers. For both species, comparing regressions of beat bucket-based counts to counts from the traditional visual method across nine cultivar and water regime combinations resulted in only one combination differing from the rest, suggesting broad applicability and ability to translate established visual-based economic thresholds to beat bucket-based thresholds. In a first look at sample size considerations, 40 plants (four 10-plant samples) per field site was no more variable than variation associated with larger sample sizes. Overall, the beat bucket is much more effective in sampling for cotton fleahopper and verde plant bug than the traditional visual method, it is more suited to cotton fleahopper sampling early-season when plants are small, it transitions well to sample for verde plant bug during bloom, and it performs well under a variety of soil moisture conditions and cultivar selections.     

Validation of 15 kGy as a radiation sterilisation dose for bone allografts manufactured at the Queensland Bone Bank: application of the VD<Subscript>max</Subscript> 15 method

Background ISO 11137-2006 (ISO 11137-2a 2006) provides a VD_max 15 method for substantiation of 15 kGy as radiation sterilisation dose (RSD) for health care products with a relatively low sample requirement. Moreover, the method is also valid for products in which the bioburden level is less than or equal to 1.5. In the literature, the bioburden level of processed bone allografts is extremely low. Similarly, the Queensland Bone Bank (QBB) usually recovers no viable organisms from processed bone allografts. Because bone allografts are treated as a type of health care product, the aim of this research was to substantiate 15 kGy as a RSD for frozen bone allografts at the QBB using method VD_max 15—ISO 11137-2: 2006 (ISO 11137-2e, Procedure for method VD_max 15 for multiple production batches. Sterilisation of health care products – radiation – part 2: establishing the sterilisation dose, 2006; ISO 11137-2f, Procedure for method VD_max 15 for a single production batch. Sterilisation of health care products – radiation – part 2: establishing the sterilisation dose, 2006). Materials 30 femoral heads, 40 milled bone allografts and 40 structural bone allografts manufactured according to QBB standard operating procedures were used. Method Estimated bioburdens for each bone allograft group were used to calculate the verification doses. Next, 10 samples per group were irradiated at the verification dose, sterility was tested and the number of positive tests of sterility recorded. If the number of positive samples was no more than 1, from the 10 tests carried out in each group, the verification was accepted and 15 kGy was substantiated as RSD for those bone allografts. Results The bioburdens in all three groups were 0, and therefore the verification doses were 0 kGy. Sterility tests of femoral heads and milled bones were all negative (no contamination), and there was one positive test of sterility in the structural bone allograft. Accordingly, the verification was accepted. Conclusion Using the ISO validated protocol, VD_max 15, 15 kGy was substantiated as RSD for frozen bone allografts manufactured at the QBB.     

Validation of Radiation Sterilization Dose for Lyophilized Amnion and Bone Grafts

A limited number of grafts produced in one batch is the main constrain to validate radiation sterilization dose of amnion and bone grafts according to ISO standard. The validation experiments done were according to ISO 13409 with a slight modification in sampling method. The experiments were carried out three times by using 20 samples each, 10 for bio-burden enumeration and 10 for sterility test at verification dose. The average bio-burden with sample item portion (SIP) = 1 for amnion membranes were 98, 50 and 69 cfu respectively and 0 cfu for bone grafts. Verification dose experiments, were done at doses of 2.90kGy for bone grafts and 5.13kGy for amnion grafts and the results of sterility tests showed that amnion grafts got one positive and bone grafts got 0 positive. The results met the requirements of ISO 13409 so that the radiation sterilization dose, at sterility assurance level of 10^-6 was 25kGy for both amnion and bone grafts. Viral contamination was excluded in this experiment.     

Parasitology: diagnostic yield of stool examination.

To assess the need for routinely submitting three stool samples per patient for recovery of enteric parasites, we reviewed the records of our parasitology laboratory for 1985-87 to determine the number of parasites that would not have been detected if only one or two samples had been submitted. A total of 16% of all stool samples were positive. For each sample that was positive for a parasite (index sample) a search was done for other stool samples, positive or negative, received from the same patient within 6 days of reception of the index sample. We identified 676 sets of two (276) or three (400) samples of which at least 1 was positive. A total of 93% of the enteric parasites were detected in the first sample in the two-sample sets. Among the three-sample sets 90% of the parasites were detected in the first sample, 8% in the second and 2% in the third. We recommend waiting for the result from the first stool sample rather than routinely submitting three samples for recovery of enteric parasites.     

Helix bending as a factor in protein/DNA recognition

Normal vectors perpendicular to individual base pairs are a powerful tool for studying the bending behavior of B-DNA, both in the form of normal vector plots and in matrices that list angles between vectors for all possible base pair combinations. A new analysis program, FREEHELIX, has been written for this purpose, and applied to 86 examples of sequence-specific protein/DNA complexes whose coordinates are on deposit in the Nucleic Acid Data Base. Bends in this sample of 86 structures almost invariably follow from roll angles between adjacent base pairs; tilt makes no net contribution. Roll in a direction compressing the broad major groove is much more common than that which compresses the minor groove. Three distinct types of B-DNA bending are observed, each with a different molecular origin: (1) Localized kinking is produced by large roll at single steps or at two steps separated by one turn of helix. (2) Smooth, planar curvature is produced by positive and negative roll angles spaced a half-turn apart, with random side-to-side zigzag roll at intermediate points, rather than a tilt contribution that might have been expected theoretically. (3) Three-dimensional writhe results from significant roll angles at a continuous series of steps. Writhe need not change the overall direction of helix axis, if it is continued indefinitely or for an integral number of helical turns. A-DNA itself can be formally considered as possessing uniform, continuous writhe that yields no net helix bending. Smooth curvature is the most intricate deformation of the three, and is least common. Writhe is the simplest deformation and is most common; indeed, a low level of continuous writhe is the normal condition of an otherwise unbent B-DNA helix of general sequence. With one exception, every example of major kinking in this sample of 86 structures involves a pyrimidine–purine step: C–A/T–G, T–A, or C–G. Purine–purine steps, especially A–A, show the least tendency toward roll deformations. © 1998 John Wiley & Sons, Inc. Biopoly 44: 361–403, 1997     

Sterility and Hypermutability in the P-M System of Hybrid Dysgenesis in DROSOPHILA MELANOGASTER

Inbred wild strains of Drosophila melanogaster derived from the central and eastern United States were used to make dysgenic hybrids in the P-M system. These strains possessed P elements and the P cytotype, the condition that represses P element transposition. Their hybrids were studied for the mutability of the P element insertion mutation, snw, and for the incidence of gonadal dysgenesis (GD) sterility. All the strains tested were able to induce hybrid dysgenesis by one or both of these assays; however, high levels of dysgenesis were rare. Sets of X chromosomes and autosomes from the inbred wild strains were more effective at inducing GD sterility than were sets of Y chromosomes and autosomes. In two separate analyses, GD sterility was positively correlated with snw mutability, suggesting a linear relationship. However, one strain appeared to induce too much GD sterility for its level of snw destabilization, indicating an uncoupling of these two manifestations of hybrid dysgenesis.     

Measurement of genotoxicity in wastewater samples with the in vitro micronucleus test: results of a round-robin study in the context of standardisation according to ISO

In the course of standardisation of the in vitro micronucleus test for analysis of effluents according to ISO, a national round-robin study was organised by the German Federal Institute of Hydrology (BfG), involving 10 laboratories of private companies, universities and public authorities. The micronucleus assay was performed with the permanently growing Chinese hamster lung fibroblast cell line V79. All participants tested four encoded samples from one municipal and one industrial wastewater treatment plant with and without metabolic activation by S9-mix. Two of these samples were spiked in advance with defined concentrations of the clastogenic substances cyclophosphamide and mitomycin C, respectively. Cyclophosphamide and ethyl methanesulfonate were used as positive controls. The defined assessment criterion for genotoxicity was the lowest dilution of a sample that does not show any significant induction of micronuclei. Cytotoxicity was judged by determining the cell-survival index, i.e. the percentage growth rate of the cells compared with the corresponding negative controls. As supplementary qualitative criteria, the mitotic index and the proliferation index were assessed. All participants successfully established the method within a few weeks and generated viable test results in time. The two non-genotoxic samples were detected as negative by 90% (with S9-mix) and 95% (without S9-mix) of the participants. The mitomycin C-spiked wastewater sample (expected to be positive without S9-mix supplementation) was correctly judged as positive by all laboratories. The cyclophosphamide-spiked sample (expected to be positive with S9-mix addition) was evaluated correctly as genotoxic by 80% of the laboratories. A post-test analysis found evidence that the false negative results were due to technical failure, but not of a methodological nature. In 94% of all tests the sample LID values (lowest ineffective dilution=dilution stage of the sample in the test at which a statistically significant increase in the micronucleus rate was not detectable any more) varied by no more than one dilution step around the median LID value. The survival index was proven to be a robust measure for estimation of toxicity. This round-robin study is the first inter-laboratory comparison of the in vitro micronucleus test using wastewater samples. The test system is intended to complement the already DIN- and ISO-standardised bacterial tests, i.e. the umu-test and the Ames plate-incorporation assay. The data provide evidence that the robust and practicable in vitro micronucleus test is suitable as a routine method for wastewater testing.     

mRNA differential display between sterile and fertile anther of rice and analysis of cDNA differential fragments

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水稻籼型光温敏核雄性不育性遗传研究

1　引　　言水稻光温敏核雄性不育性是一种典型的生态遗传现象 ,其遗传行为既受内部基因控制 ,又受外部光、温等生态因子的调节 ,还与所处的遗传背景密切相关 .前人已对农垦 5 8Ｓ及其衍生系等粳型光温敏核不育性有过较系统地研究 ,并提出一对、二对、三对和重复基因突变等多种假说[3 ,5,7～ 9] ;但对籼型及非农垦 5 8Ｓ基因源的光温敏核不育性研究较少 .本文采用极大似然法 ,对不同来源的籼型光温敏核不育性进行系统研究 ,旨在揭示其遗传本质 ,为解决两系法杂交水稻推广过程中出现的不育起点温度“漂移”等问题提供理论依据 .2　材料与方法…     

Influence of fenoxycarb on German cockroach (Dictyoptera: Blattellidae) populations in public housing

In a study examining three application rates for fenoxycarb, new interpretations of population age structure in relation to sterility levels and population reductions were used to establish important concepts in the management of German cockroaches, Blattella germanica (L.), with juvenoids. No significant differences in population reductions were noted when 0.5%, 0.25%, or 0.125% fenoxycarb was used to supplement propetamphos. However, significant differences in levels of induced sterility and in the age structure (measured as nymph-to-adult ratios) of treated populations were detected. The 0.125% rate caused lower, less consistent levels of sterility than the two higher rates, which maintained approximately 80% sterility from 4.5 mo and beyond. In addition, the 0.125% rate did not significantly reduce nymph-to-adult ratios in treated populations relative to that caused by the propetamphos alone (positive control). The two higher rates significantly reduced nymph-to-adult ratios, thereby lowering biotic potential and the capacity of a population to rebound from suppression. A relationship between the level of sterility induced by juvenoids and reductions in nymph-to-adult ratios permitted formulation of a biological action threshold for regulating treatment. This action threshold appears to be more meaningful than time intervals for scheduling retreatments in the long-term management of German cockroaches with juvenoids.     

Translocations, the Predominant Cause of Total Sterility in Sons of Mice Treated with Mutagens

Histological and cytological analyses of the testes were carried out in 42 sterile sons of males treated in the spermatozoal or spermatid stage with 250 mg/kg ethyl methanesulfonate (EMS) alone or after prefeeding with butylated hydroxytoluene (BHT); or treated with 200 R X-rays. Of the 42 sterile males, 17 had some mature spermatids, nine were blocked at diakinesis, 15 were blocked in pachytene, and one lacked spermatogenic cells altogether, having Sertoli cells only. Mitotic (spermatogonial) metaphases could therefore be analyzed in 41 of the males and meiotic configurations in 26.-(1) None of the males showed abnormalities in chromosome number, such as monosomy, trisomy, or mosaicism for either of these conditions. Certain classes of chromosome abnormalities that have been found associated with male sterility in other investigations, namely trisomies, XXY's, and X-autosome translocations, are not expected from treatment of 19A + Y cells when F(1) males are studied. (2) A very high percentage of the sterile males carried translocations. Direct meiotic evidence for this was found in 22 of the animals. In addition, 11 of the 16 that were blocked (or virtually blocked) in pachytene, and thus could be analyzed in mitosis only, consistently showed one abnormally short chromosome (or, one short plus one long), which presumably had resulted from unequal exchange (or sizable deficiency). Of the meiotically detected translocation males, 1 carried a T(A;Y), 17 had single autosomal translocations, and 4 had multiple autosomal rearrangements involving three, four, four, and six breaks, respectively. In addition, three males showed failure of X-Y pairing. (3) Translocations that cause sterility, rather than partial sterility, in males appear to be those in which at least one of the breaks occurs close to one end of a chromosome. The mitotic and meiotic evidences for this were found to be correlated. (4) It is proposed that many cases of induced F(1) male sterility may be the result of position effects produced when paracentromeric regions are translocated to euchromatic regions of certain other chromosomes. Since many translocations that produce partial sterility in the female cause complete sterility in the male, the male must be assumed to be more susceptible to disturbances of fertility by the postulated mechanism. (5) There is evidence that EMS, especially in the lower dose range, more often breaks chromosomes near one of their ends than does X-irradiation.     

光周期敏感细胞质雄性不育小麦的研究

选用我们创建的Ｄ＾２型细胞质与普通小麦品种,经多年回交核置换获得的１５种异质系在,不同发育期置于武汉不同光长条件下,并春播于哈尔滨自然长日条件下,抽穗时套袋自产,进行碘染花分观察,成熟后考察自交结实率等。     

Interspecific Tests of Allelism Reveal the Evolutionary Timing and Pattern of Accumulation of Reproductive Isolation Mutations

Despite extensive theory, little is known about the empirical accumulation and evolutionary timing of mutations that contribute to speciation. Here we combined QTL (Quantitative Trait Loci) analyses of reproductive isolation, with information on species evolutionary relationships, to reconstruct the order and timing of mutations contributing to reproductive isolation between three plant (Solanum) species. To evaluate whether reproductive isolation QTL that appear to coincide in more than one species pair are homologous, we used cross-specific tests of allelism and found evidence for both homologous and lineage-specific (non-homologous) alleles at these co-localized loci. These data, along with isolation QTL unique to single species pairs, indicate that >85% of isolation-causing mutations arose later in the history of divergence between species. Phylogenetically explicit analyses of these data support non-linear models of accumulation of hybrid incompatibility, although the specific best-fit model differs between seed (pairwise interactions) and pollen (multi-locus interactions) sterility traits. Our findings corroborate theory that predicts an acceleration (‘snowballing’) in the accumulation of isolation loci as lineages progressively diverge, and suggest different underlying genetic bases for pollen versus seed sterility. Pollen sterility in particular appears to be due to complex genetic interactions, and we show this is consistent with a snowball model where later arising mutations are more likely to be involved in pairwise or multi-locus interactions that specifically involve ancestral alleles, compared to earlier arising mutations.     

Comparative protein population investigation of the Alnus serrulatarugosa complex

The data from electrophoretic and serological studies with proteins extracted from pollen from: eight populations of the Alnus serrulata-rugosa complex indicate that some bands of the protein pattern (Type A bands) were consistently present in all the samples collected from various populations. The Type A band pattern was not influenced by individual genotypes or environmental differences. Attempts to use bands other than those of Type A in the characterization of populations within the complex did not prove valuable. The importance of using a sample size large enough to cope with the problem of variability within a population was revealed. The data obtained by the use of qualitative serological techniques (Ouchterlony method) agreed with those obtained by the quantitative turbidimetric procedure (Boyden procedure). Serology differences among populations within the complex were not detected. However, marked differences were detected when compared to Betula populifolia, another genus in the same family. All but one sample of seeds of the complex studied revealed 95% sterility because of abnormal embryo development. Viability pollen tests of the 14 samples from the eight populations revealed 94–99% viability. We believe that a taxonomic treatment which designates this complex as one species with varieties or subspecies is the best interpretation of the data available from diverse disciplines and several independent studies.     

The weighted generalized estimating equations approach for the evaluation of medical diagnostic test at subunit level

Sensitivity and specificity are common measures used to evaluate the performance of a diagnostic test. A diagnostic test is often administrated at a subunit level, e.g. at the level of vessel, ear or eye of a patient so that the treatment can be targeted at the specific subunit. Therefore, it is essential to evaluate the diagnostic test at the subunit level. Often patients with more negative subunit test results are less likely to receive the gold standard tests than patients with more positive subunit test results. To account for this type of missing data and correlation between subunit test results, we proposed a weighted generalized estimating equations (WGEE) approach to evaluate subunit sensitivities and specificities. A simulation study was conducted to evaluate the performance of the WGEE estimators and the weighted least squares (WLS) estimators (Barnhart and Kosinski, 2003) under a missing at random assumption. The results suggested that WGEE estimator is consistent under various scenarios of percentage of missing data and sample size, while the WLS approach could yield biased estimators due to a misspecified missing data mechanism. We illustrate the methodology with a cardiology example.     

The synergistic effect of X-rays and deficiencies in DNA repair in P-M hybrid dysgenesis in Drosophila melanogaster.

X-rays and deficiencies in DNA repair had a synergistic effect on genetic damage associated with P-element mobility in Drosophila melanogaster. These interactions, using sterility and fecundity as endpoints, were tested in dysgenic males deficient in either excision or post-replication DNA repair. Three sublines of the Harwich P strain were used for the construction of hybrid males. These sublines differ in P-induction ability based on gonadal dysgenesis sterility (GD) and snw mutability tests, in P-element insertion site pattern, and in the types of defective P-elements, such as KP elements, they possess. A lower degree of gonadal dysgenesis was correlated with the presence of KP elements. GD sterility and snw mutability were not always correlated. Dysgenic hybrids originating from the standard reference subline, Harwich(white), were much more sensitive to the post-replication repair than the excision repair defect. In contrast, sterility of hybrids derived from the weak subline was least affected by, and that of hybrids of the strongest subline was most affected by either DNA repair deficiency. The exacerbation by X-rays of the effects of DNA repair deficiencies on genetic damage indicates that both repair mechanisms are required for processing DNA lesions induced by the combined effect of P activity and ionizing radiation.     

The STRS (shortness of breath, tremulousness, racing heart, and sweating): A brief checklist for acute distress with panic-like autonomic indicators; development and factor structure

BACKGROUND: Peritraumatic response, as currently assessed by Posttraumatic Stress Disorder (PTSD) diagnostic criterion A2, has weak positive predictive value (PPV) with respect to PTSD diagnosis. Research suggests that indicators of peritraumatic autonomic activation may supplement the PPV of PTSD criterion A2. We describe the development and factor structure of the STRS (Shortness of Breath, Tremulousness, Racing Heart, and Sweating), a one page, two-minute checklist with a five-point Likert-type response format based on a previously unpublished scale. It is the first validated self-report measure of peritraumatic activation of the autonomic nervous system. METHODS: We selected items from the Potential Stressful Events Interview (PSEI) to represent two latent variables: 1) PTSD diagnostic criterion A, and 2) acute autonomic activation. Participants (a convenience sample of 162 non-treatment seeking young adults) rated the most distressing incident of their lives on these items. We examined the factor structure of the STRS in this sample using factor and cluster analysis. RESULTS: Results confirmed a two-factor model. The factors together accounted for 68% of the variance. The variance in each item accounted for by the two factors together ranged from 41% to 74%. The item loadings on the two factors mapped precisely onto the two proposed latent variables. CONCLUSION: The factor structure of the STRS is robust and interpretable. Autonomic activation signs tapped by the STRS constitute a dimension of the acute autonomic activation in response to stress that is distinct from the current PTSD criterion A2. Since the PTSD diagnostic criteria are likely to change in the DSM-V, further research is warranted to determine whether signs of peritraumatic autonomic activation such as those measured by this two-minute scale add to the positive predictive power of the current PTSD criterion A2. Additionally, future research is warranted to explore whether the four automatic activation items of the STRS can be useful as the basis for a possible PTSD criterion A3 in the DSM-V.     

Height and cognitive achievement among Indian children

Taller children perform better on average on tests of cognitive achievement, in part because of differences in early-life health and net nutrition. Recent research documenting this height-achievement slope has primarily focused on rich countries. Using the India Human Development Survey, a representative sample of 40,000 households which matches anthropometric data to learning tests, this paper documents a height-achievement slope among Indian children. The height-achievement slope in India is more than twice as steep as in the U.S. An earlier survey interviewed some IHDS children's households eleven years before. Including matched early-life control variables reduces the apparent effect of height, but does not eliminate it; water, sanitation, and hygiene may be particularly important for children's outcomes. Being one standard deviation taller is associated with being 5 percentage points more likely to be able to write, a slope that falls only to 3.4 percentage points controlling for a long list of contemporary and early-life conditions.