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We develop a framework for self-consistently extracting cosmological information from the clustering of tracers in redshift space, without relying on model-dependent templates to describe the baryon acoustic oscillation (BAO) feature. Our approach uses the recently proposed Laguerre reconstruction technique for the BAO feature and its linear point r LP, and substantially extends it to simultaneously model the multipoles ℓ = 0, 2, 4 of the anisotropic galaxy 2-point correlation function (2pcf). The approach is 'model-agnostic': it assumes that the nonlinear growth of structure smears the BAO feature by an approximately Gaussian kernel with a smearing scale σv, but does not assume any fiducial cosmology for describing the shape of the feature itself. Using mock observations for two realistic survey configurations assuming Λ cold dark matter (ΛCDM), combined with Bayesian parameter inference, we show that the linear point r LP and smearing scale σv can be accurately recovered by our method in both existing and upcoming surveys. The precision of the recovery of r LP is always better than |$1{{\ \rm per\ cent}}$|⁠ , while σv can be recovered with |$\lesssim 10{{\ \rm per\ cent}}$| uncertainty provided the linear galaxy bias b is separately constrained, e.g. using weak lensing observations. Our method is also sensitive to the linear growth rate f , albeit with larger uncertainties and systematic errors, especially for upcoming surveys such as DESI. We discuss how our model can be modified to improve the recovery of f , such that the resulting constraints on { f , σv, r LP} can potentially be used as a test of cosmological models including and beyond ΛCDM. [ABSTRACT FROM AUTHOR]

Background: Emergence of the new SARS-CoV-2 variant B.1.1.529 worried health policy makers worldwide due to a large number of mutations in its genomic sequence, especially in the spike protein region. The World Health Organization (WHO) designated this variant as a global variant of concern (VOC), which was named "Omicron." Following Omicron's emergence, a surge of new COVID-19 cases was reported globally, primarily in South Africa. Objective: The aim of this study was to understand whether Omicron had an epidemiological advantage over existing variants. Methods: We performed an in silico analysis of the complete genomic sequences of Omicron available on the Global Initiative on Sharing Avian Influenza Data (GISAID) database to analyze the functional impact of the mutations present in this variant on virus-host interactions in terms of viral transmissibility, virulence/lethality, and immune escape. In addition, we performed a correlation analysis of the relative proportion of the genomic sequences of specific SARS-CoV-2 variants (in the period from October 1 to November 29, 2021) with matched epidemiological data (new COVID-19 cases and deaths) from South Africa. Results: Compared with the current list of global VOCs/variants of interest (VOIs), as per the WHO, Omicron bears more sequence variation, specifically in the spike protein and host receptor-binding motif (RBM). Omicron showed the closest nucleotide and protein sequence homology with the Alpha variant for the complete sequence and the RBM. The mutations were found to be primarily condensed in the spike region (n=28-48) of the virus. Further mutational analysis showed enrichment for the mutations decreasing binding affinity to angiotensin-converting enzyme 2 receptor and receptor-binding domain protein expression, and for increasing the propensity of immune escape. An inverse correlation of Omicron with the Delta variant was noted (r=-0.99, P<.001; 95% CI -0.99 to -0.97) in the sequences reported from South Africa postemergence of the new variant, subsequently showing a decrease. There was a steep rise in new COVID-19 cases in parallel with the increase in the proportion of Omicron isolates since the report of the first case (74%-100%). By contrast, the incidence of new deaths did not increase (r=-0.04, P>.05; 95% CI -0.52 to 0.58). Conclusions: In silico analysis of viral genomic sequences suggests that the Omicron variant has more remarkable immune-escape ability than existing VOCs/VOIs, including Delta, but reduced virulence/lethality than other reported variants. The higher power for immune escape for Omicron was a likely reason for the resurgence in COVID-19 cases and its rapid rise as the globally dominant strain. Being more infectious but less lethal than the existing variants, Omicron could have plausibly led to widespread unnoticed new, repeated, and vaccine breakthrough infections, raising the population-level immunity barrier against the emergence of new lethal variants. The Omicron variant could have thus paved the way for the end of the pandemic. [ABSTRACT FROM AUTHOR]

We study the role of the local tidal environment in determining the assembly bias of dark matter haloes. Previous results suggest that the anisotropy of a halo's environment (i.e. whether it lies in a filament or in a more isotropic region) can play a significant role in determining the eventual mass and age of the halo. We statistically isolate this effect, using correlations between the large-scale and small-scale environments of simulated haloes at z  = 0 with masses between 1011.6 ≲ (m / h −1 M⊙) ≲ 1014.9. We probe the large-scale environment, using a novel halo-by-halo estimator of linear bias. For the small-scale environment, we identify a variable α R that captures the tidal anisotropy in a region of radius R  = 4 R 200b around the halo and correlates strongly with halo bias at fixed mass. Segregating haloes by α R reveals two distinct populations. Haloes in highly isotropic local environments (α R ≲ 0.2) behave as expected from the simplest, spherically averaged analytical models of structure formation, showing a negative correlation between their concentration and large-scale bias at all masses. In contrast, haloes in anisotropic, filament-like environments (α R ≳ 0.5) tend to show a positive correlation between bias and concentration at any mass. Our multiscale analysis cleanly demonstrates how the overall assembly bias trend across halo mass emerges as an average over these different halo populations, and provides valuable insights towards building analytical models that correctly incorporate assembly bias. We also discuss potential implications for the nature and detectability of galaxy assembly bias. [ABSTRACT FROM AUTHOR]

The simplest analyses of halo bias assume that halo mass alone determines halo clustering. However, if the large-scale environment is fixed, then halo clustering is almost entirely determined by environment, and is almost completely independent of halo mass. We show why. Our analysis is useful for studies that use the environmental dependence of clustering to constrain cosmological and galaxy formation models. It also shows why many correlations between galaxy properties and environment are merely consequences of the underlying correlations between haloes and their environments, and provides a framework for quantifying such inherited correlations. [ABSTRACT FROM AUTHOR]

Barium esophagrams are a frequently performed test, and radiological observations about potential abnormal esophageal motility, such as tertiary contractions, are commonly reported. We sought to assess the correlation between tertiary waves, and in particular isolated tertiary waves, on esophagrams and findings on non-synchronous high-resolution esophageal manometry. We retrospectively reviewed reports of esophagrams performed at a tertiary referral center and identified patients in whom tertiary waves were observed and a high-resolution esophageal manometry had been performed. We defined two groups; group 1 was defined as patients with isolated tertiary waves, whereas group 2 had tertiary waves and evidence of achalasia or an obstructing structural abnormality on the esophagram. We collected data on demographics, dysphagia score, associated findings on esophagram, and need for intervention. We reviewed the reports of 2100 esophagrams of which tertiary waves were noted as an isolated abnormality in 92, and in association with achalasia or a structural obstruction in 61. High-resolution manometry was performed in 17 patients in group 1, and five had evidence of a significant esophageal motility disorder and 4 required any intervention. Twenty-one patients in group 2 underwent manometry, and 18 had a significant esophageal motility disorder. An isolated finding of tertiary waves on an esophagram is rarely associated with a significant esophageal motility disorder that requires intervention. All patients with isolated tertiary waves who required intervention had a dysphagia to liquids. Tertiary contractions, in the absence of dysphagia to liquids, indicate no significant esophageal motility disorder. [ABSTRACT FROM AUTHOR]

Background. Vascular endothelial growth factor and platelet-derived growth factor signaling in the tumor microenviron-ment appear to cooperate in promoting tumor angiogenesis. Patients and Methods. We conducted a phase I trial combining bevacizumab (i.v. every 2 weeks) and imatinib (oral daily). Once a recommended phase II dose combination was established, a phase II trial was initiated in patients with metastatic melanoma. A Simon 2-stage design was used with 23 patients required in the first stage and 41 patients in total should the criteria to proceed be met. We required that 50% of the patients be progression-free at 16 weeks. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and power Doppler ultrasonography were performed in patients with metastatic tumors amenable to imaging with these methods at baseline and after 4 weeks. Results. A total of 17 patients were accrued to 4 dose and combination levels. Bevacizumab 10 mg/kg every 2 weeks could be safely combined with imatinib 800 mg daily. Common toxicities included fatigue, nausea, vomiting, edema, protein-uria, and anemia, but were not commonly severe. A total of 23 patients with metastatic melanoma (48% with American Joint Commission on Cancer stage M1c; median age, 63 years) were enrolled in the first stage of phase II. The 16-week progression-free survival rate was 35%, leading to termination of phase II after the first stage. In the small subset of patients who remained on study with lesions evaluable by DCE-MRI, significant decreases in tumor vascular permeability were noted, despite early disease progression using the Response Evaluation Criteria In Solid Tumors. Conclusion. Bevacizumab and imatinib can be safely combined at the maximum doses used for each agent. We did not observe significant clinical activity with this regimen in melanoma patients. [ABSTRACT FROM AUTHOR]

Women in low- and middle-income countries (LMICs) facing poverty, challenging living conditions, and gender inequality often express their emotional difficulties through physical health concerns. These women seek care at primary health facilities. However, primary care providers in LMICs only treat the physical health symptoms and lack appropriate services to address women's mental health problems. This article presents data from the counseling component of a multilevel, research and intervention project in a low-income community in Mumbai, India, whose objective was to improve sexual health and reduce HIV/STI risk among married women. Qualitative data from counselor notes show that poor mental health, associated with negative and challenging life situations, is most often expressed by women as gynecological concerns through the culturally based syndrome of tenshun. A path analysis was conducted on baseline quantitative data that confirmed the relationships between sources of tenshun, emotional status, and symptoms of common mental disorders (CMDs). Based on these findings, the authors propose a need for culturally appropriate primary care services for LMICs that would integrate mental and physical health. This approach would reduce mental health morbidity among women through early intervention and prevention of the development of CMDs. [ABSTRACT FROM AUTHOR]

Aims (1) To determine whether measured concentrations of delta-9-tetrahydrocannabinol ( THC) and cannabidiol ( CBD) in individuals' own cannabis predict their estimates of drug potency and actual titration; and (2) to ascertain if these effects are influenced by frequency of use and cannabis type. Design Cross-sectional, naturalistic. Setting Participants' own homes. Participants A total of 247 cannabis users in the United Kingdom: 152 'recreational' (1-24 days/month) and 95 'daily' (≥25 days/month). Methods Participants rated their own cannabis for its potency (1-10) and type ('resin', 'herbal', 'skunk') before smoking it in front of the researcher. The amount of cannabis (g) used in their joints was recorded and an additional sample was analysed for THC and CBD concentrations (%). Findings THC concentrations were related negatively to the amount of cannabis used [unstandardized regression coefficient: b = −0.009, 95% confidence interval ( CI) = −0.017, −0.002]. Potency estimates were predicted by increasing THC (b = 0.055, 95% CI = 0.020, 0.090) and decreasing CBD (b = −0.160, 95% CI = −0.284, −0.062), and both of these associations were mediated by cannabis type ( THC: b = 0.018, 95% CI = 0.006, 0.037; CBD: b = −0.105, 95% CI = −0.198, −0.028). Potency estimates were more reflective of THC as frequency of use increased (b = 0.004, 95% CI = 0.001, 0.007) and were 7.3 times more so in daily (partial r = 0.381) than recreational users ( r = 0.052). Conclusions When using their own cannabis in a naturalistic setting, people titrate the amount they roll in joints according to concentrations of delta-9-tetrahydrocannabinol ( THC) but not cannabidiol ( CBD). Recreational users thus show poor understanding of cannabis potency. [ABSTRACT FROM AUTHOR]

This paper examines the relationship of empowerment to women's self-reported general health status and women's self-reported health during pregnancy in low-income communities in Mumbai. The data on which this paper is based were collected in three study communities located in a marginalised area of Mumbai. We draw on two data sources: in-depth qualitative interviews conducted with 66 married women and a survey sample of 260 married women. Our analysis shows that empowerment functions differently in relation to women's reproductive status. Non-pregnant women with higher levels of empowerment experience greater general health problems, while pregnant women with higher levels of empowerment are less likely to experience pregnancy-related health problems. We explain this non-intuitive finding and suggest that a globally defined empowerment measure for women may be less useful that one that is contextually and situationally defined. [ABSTRACT FROM AUTHOR]

Smoking is common in patients with HIV and is associated with increased morbidity and mortality. With the goal of targeting future cessation interventions, we sought to identify factors associated with smoking status, readiness and confidence in cessation, and success in quitting. As part of a larger study in New York City assessing predictors of chronic obstructive pulmonary disease (COPD), we enrolled HIV-infected subjects at least 35 years of age without known asthma or COPD. Current smokers received detailed tobacco history, and smoking status was assessed by chart review at 3 and 6 months post-enrollment. Two hundred subjects were enrolled (29% current smokers, 31.5% never smokers, 39.5% former smokers, mean age of 49, 84% male, 64% had AIDS, and 97% were receiving antiretroviral therapy). Current smokers had higher unemployment and increased rates of other substance use than former smokers or never smokers. In multivariate analysis, being unemployed and having used inhalant drugs were associated with current smoking. Substance abuse history was not correlated with readiness to quit or patient estimated cessation. Lower education was associated with decreased readiness to quit. Follow-up smoking status for baseline current smokers was available for 47/58 enrollees at 6 months; 4 (9%) stopped smoking completely, and 17 (36%) decreased the number of packs-per-day. Smoking and concomitant substance abuse is common in HIV, and special attention should be given to this issue, in addition to a patient's readiness to quit, when implementing tobacco cessation protocols, especially in busy urban HIV care centers. [ABSTRACT FROM AUTHOR]

Motivated by the recent detection of an enhanced clustering signal along the major axis of haloes in N-body simulations, we derive a formula for the anisotropic density distribution around haloes and voids on large scales. Our model, which assumes linear theory and that the formation and orientation of non-linear structures are strongly correlated with the Lagrangian shear, is in good agreement with measurements. We also show that the measured amplitude is inconsistent with a model in which the alignment is produced by the initial inertia rather than shear tensor. [ABSTRACT FROM AUTHOR]

ABSTRACT We provide a simple formula that accurately approximates the first crossing distribution of barriers having a wide variety of shapes, by random walks with a wide range of correlations between steps. Special cases of it are useful for estimating halo abundances, evolution and bias, as well as the non-linear counts in cells distribution. We discuss how it can be extended to allow for the dependence of the barrier on quantities other than overdensity, to construct an excursion set model for peaks, and to show why assembly and scale-dependent bias are generic even at the linear level. [ABSTRACT FROM AUTHOR]

ABSTRACT Estimates of the coefficients a and b of the Fundamental Plane relation R∝σ a Ib depend on whether one minimizes the scatter in the R direction, or orthogonal to the plane. We provide explicit expressions for a and b (and confidence limits) in terms of the covariances between log R, log σ and log I. Our expressions quantify the origin of the difference between the direct, inverse and orthogonal fit coefficients. They also show how to account for correlated errors, how to quantify the difference between the plane in a magnitude-limited survey and one which is volume limited, how to determine whether a scaling relation will be biased when using an apparent magnitude-limited survey, how to remove this bias and why some forms of the z≈ 0 plane appear to be less affected by selection effects, but that this does not imply that they will remain unaffected at high redshift. Finally, they show why, to a good approximation, the three vectors associated with the plane, one orthogonal to and the other two in it, can all be written as simple combinations of a and b. Essentially, this is a consequence of the fact that the distribution of surface brightness is much broader than that of velocity dispersions, and velocity dispersion and surface brightness are only weakly correlated. Why this should be so for galaxies is a fundamental open question about the physics of early-type galaxy formation. We argue that if luminosity evolution is differential, and sizes and velocity dispersions do not evolve, then this is just an accident: velocity dispersion and surface brightness must have been correlated in the past. On the other hand, if the (lack of) correlation is similar to that at the present time, then differential luminosity evolution must have been accompanied by structural evolution. A model in which the luminosities of low-luminosity galaxies evolve more rapidly than do those of higher luminosity galaxies is able to produce the observed decrease in a (by a factor of 2 at z∼ 1) while having b decrease by only about 20 per cent. In such a model, the dynamical mass-to-light ratio is a steeper function of mass at higher z. Our analysis is more generally applicable to any other correlations between three variables: e.g. the colour-magnitude-σ relation, the luminosity and velocity dispersion of a galaxy and the mass of its black hole or the relation between the X-ray luminosity, Sunyaev-Zeldovich decrement and optical richness of a cluster. Furthermore, for completeness, we show how our analysis generalizes further to correlations between more than three variables. [ABSTRACT FROM AUTHOR]

ABSTRACT The excursion set approach has been used to make predictions for a number of interesting quantities in studies of non-linear hierarchical clustering. These include the halo mass function, halo merger rates, halo formation times and masses, halo clustering, analogous quantities for voids and the distribution of dark matter counts in randomly placed cells. The approach assumes that all these quantities can be mapped to problems involving the first-crossing distribution of a suitably chosen barrier by random walks. Most analytic expressions for these distributions ignore the fact that, although different k-modes in the initial Gaussian field are uncorrelated, this is not true in real space: the values of the density field at a given spatial position, when smoothed on different real-space scales, are correlated in a non-trivial way. As a result, the problem is to estimate first crossing distribution by random walks having correlated rather than uncorrelated steps. In 1990, Peacock & Heavens presented a simple approximation for the first crossing distribution of a single barrier of constant height by walks with correlated steps. We show that their approximation can be thought of as a correction to the distribution associated with what we call smooth completely correlated walks. We then use this insight to extend their approach to treat moving barriers, as well as walks that are constrained to pass through a certain point before crossing the barrier. For the latter, we show that a simple rescaling, inspired by bivariate Gaussian statistics, of the unconditional first crossing distribution, accurately describes the conditional distribution, independent of the choice of analytical prescription for the former. In all cases, comparison with Monte Carlo solutions of the problem shows reasonably good agreement. This represents the first explicit demonstration of the accuracy of an analytic treatment of all these aspects of the correlated steps problem. While our main focus is on first crossing distributions of deterministic barriers by random walks, in Appendices we also discuss several issues that arise upon introducing a stochasticity in the barrier height, a topic which has gained interest recently with regard to the mapping between first crossing distributions and halo mass functions. [ABSTRACT FROM AUTHOR]

ABSTRACT We extend earlier work on the problem of estimating the void-volume function - the abundance and evolution of large voids which grow gravitationally in an expanding universe - in two ways. The first removes an ambiguity about how the void-in-cloud process, which erases small voids, should be incorporated into the excursion set approach. The main technical change here is to think of voids within a fully Eulerian, rather than purely Lagrangian, framework. The second accounts for correlations between different spatial scales in the initial conditions. We provide numerical and analytical arguments showing how and why both changes modify the predicted abundances substantially. In particular, we show that the predicted importance of the void-in-cloud process depends strongly on whether or not one accounts for correlations between scales. With our new formulation, the void-in-cloud process dramatically reduces the predicted abundances of voids if such correlations are ignored, but only matters for the smallest voids in the more realistic case in which the spatial correlations are included. [ABSTRACT FROM AUTHOR]

Three series of styryl aryl ketones (E-2-propen-1-ones) are synthesized by solvent free method carried out by grinding the benzaldehydes and the aryl methyl ketones in the presence of solid sodium hydroxide. They are characterized by physical constants and spectral data. From infrared spectral data, the deformation modes of C-H in-plane/outof- plane, -CH=CH- and >C=C< out-of-plane of the vinyl parts are assigned. With the help of regression analysis, the deformation modes have been correlated with Hammett substituent constants. From the results of statistical analysis the effects of substituent on the above deformation modes have been explained. The anti-plasmoidal potential is evaluated for the synthesized chalcones. [ABSTRACT FROM AUTHOR]

The peak-background split argument is commonly used to relate the abundance of dark matter haloes to their spatial clustering. Testing this argument requires an accurate determination of the halo mass function. We present a maximum-likelihood method for fitting parametric functional forms to halo abundances which differs from previous work because it does not require binned counts. Our conclusions do not depend on whether we use our method or more conventional ones. In addition, halo abundances depend on how haloes are defined. Our conclusions do not depend on the choice of link length associated with the friends-of-friends halo finder, nor do they change if we identify haloes using a spherical overdensity algorithm instead. The large-scale halo bias measured from the matter–halo cross spectrum and the halo autocorrelation function (on scales and Mpc) can differ by as much as 5 per cent for haloes that are significantly more massive than the characteristic mass M*. At these large masses, the peak-background split estimate of the linear bias factor b1 is 3–5 per cent smaller than , which is 5 per cent smaller than . We discuss the origin of these discrepancies: deterministic non-linear local bias, with parameters determined by the peak-background split argument, is unable to account for the discrepancies we see. A simple linear but non-local bias model, motivated by peaks theory, may also be difficult to reconcile with our measurements. More work on such non-local bias models may be needed to understand the nature of halo bias at this level of precision. [ABSTRACT FROM AUTHOR]

We present an analysis of the small-to-intermediate scale clustering of samples of luminous red galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS) and the 2dF-SDSS LRG and QSO Survey (2SLAQ) survey carefully matched to have the same rest-frame colours and luminosity. We study the spatial two-point autocorrelation function in both redshift space and real space of a combined sample of over 10 000 LRGs, which represent the most massive galaxies in the universe with stellar masses and space densities . We find no significant evolution in the amplitude ( r0) of the correlation function with redshift, but do see a slight decrease in the slope (γ) with increasing redshift over and scales of . We compare our measurements with the predicted evolution of dark matter clustering and use the halo model to interpret our results. We find that our clustering measurements are inconsistent (>99.9 per cent significance) with a passive model whereby the LRGs do not merge with one another; a model with a merger rate of 7.5 ± 2.3 per cent from to 0.19 (i.e. an average rate of 2.4 per cent Gyr−1) provides a better fit to our observations. Our clustering and number density measurements are consistent with the hypothesis that the merged LRGs were originally central galaxies in different haloes which, following the merger of these haloes, merged to create a single brightest cluster galaxy. In addition, we show that the small-scale clustering signal constrains the scatter in halo merger histories. When combined with measurements of the luminosity function, our results suggest that this scatter is sub-Poisson. While this is a generic prediction of hierarchical models, it has not been tested before. [ABSTRACT FROM AUTHOR]

We present measurements of the redshift-space three-point correlation function of 50 967 luminous red galaxies (LRGs) from Data Release 3 (DR3) of the Sloan Digital Sky Survey (SDSS). We have studied the shape dependence of the reduced three-point correlation function on three different scales, and , and over the range of and . On small scales is nearly constant, with little change as a function of q and θ. However, there is evidence for a shallow U-shaped behaviour (with θ) which is expected from theoretical modelling of . On larger scales ( and ), the U-shaped anisotropy in (with θ) is more clearly detected. We compare this shape dependence in with that seen in mock galaxy catalogues which were generated by populating the dark matter haloes in large N-body simulations with mock galaxies using various halo occupation distributions (HOD). We find that the combination of the observed number density of LRGs, the (redshift-space) two-point correlation function and provides a strong constraint on the allowed HOD parameters and breaks key degeneracies between these parameters. For example, our observed disfavours mock catalogues that overpopulate massive dark matter haloes with many LRG satellites. We also estimate the linear bias of LRGs to be in excellent agreement with other measurements. [ABSTRACT FROM AUTHOR]

We discuss two slightly counterintuitive findings about the environmental dependence of clustering in the Sloan Digital Sky Survey. First, we find that the relation between clustering strength and density is not monotonic: galaxies in the densest regions are more strongly clustered than are galaxies in regions of moderate overdensity; galaxies in moderate overdensities are more strongly clustered than are those in moderate underdensities; but galaxies in moderate underdensities are less clustered than galaxies in the least dense regions. We argue that this is natural if clustering evolved gravitationally from a Gaussian field, since the highest peaks and lowest troughs in Gaussian fields are similarly clustered. The precise non-monotonic dependence of galaxy clustering on density is very well reproduced in a mock catalogue which is based on a halo model decomposition of galaxy clustering. In the mock catalogue, haloes of different masses are all about 200 times denser than the critical density, and the dependence of small-scale clustering on environment is entirely a consequence of the fact that the halo mass function in dense regions is top-heavy – another natural prediction of clustering from Gaussian initial conditions. Secondly, the distribution of galaxy counts in our sample is rather well described by a Poisson cluster model. We show that, despite their Poisson nature, correlations with environment are expected in such models. More remarkably, the expected trends are very like those in standard models of halo bias, despite the fact that correlations with environment in these models arise purely from the fact that dense regions are dense because they happen to host more massive haloes. This is in contrast to the usual analysis which assumes that it is the large-scale environment which determines the halo mass function. [ABSTRACT FROM AUTHOR]

Marked statistics allow sensitive tests of how galaxy properties correlate with environment, as well as of how correlations between galaxy properties are affected by environment. A halo-model description of marked correlations is developed, which incorporates the effects which arise from the facts that typical galaxy marks (e.g. luminosity, colour, star formation rate, stellar mass) depend on the mass of the parent halo, and that massive haloes extend to larger radii and populate denser regions. Comparison with measured marked statistics in semi-analytic galaxy formation models shows good agreement on scales smaller than a megaparsec, and excellent agreement on larger scales. The halo-model description shows clearly that the behaviour of some low-order marked statistics on these scales encodes information about the mean galaxy mark as a function of halo mass, but is insensitive to mark gradients within haloes. Higher-order statistics encode information about higher-order moments of the distribution of marks within haloes. This information is obtained without ever having to identify haloes or clusters in the galaxy distribution. On scales smaller than a megaparsec, the halo-model calculation shows that marked statistics allow sensitive tests of whether or not central galaxies in haloes are a special population. A prescription for including more general mark gradients in the halo-model description is also provided. The formalism developed here is particularly well suited to interpretation of marked statistics in astrophysical data sets, because it is phrased in the same language that is currently used to interpret more standard measures of galaxy clustering. [ABSTRACT FROM AUTHOR]