A broadband thermal emission spectrum of the ultra-hot Jupiter WASP-18b.

Close-in giant exoplanets with temperatures greater than 2,000 K ('ultra-hot Jupiters') have been the subject of extensive efforts to determine their atmospheric properties using thermal emission measurements from the Hubble Space Telescope (HST) and Spitzer Space Telescope1-3. However, previous studies have yielded inconsistent results because the small sizes of the spectral features and the limited information content of the data resulted in high sensitivity to the varying assumptions made in the treatment of instrument systematics and the atmospheric retrieval analysis3-12. Here we present a dayside thermal emission spectrum of the ultra-hot Jupiter WASP-18b obtained with the NIRISS13 instrument on the JWST. The data span 0.85 to 2.85 µm in wavelength at an average resolving power of 400 and exhibit minimal systematics. The spectrum shows three water emission features (at >6σ confidence) and evidence for optical opacity, possibly attributable to H-, TiO and VO (combined significance of 3.8σ). Models that fit the data require a thermal inversion, molecular dissociation as predicted by chemical equilibrium, a solar heavy-element abundance ('metallicity', [Formula: see text] times solar) and a carbon-to-oxygen (C/O) ratio less than unity. The data also yield a dayside brightness temperature map, which shows a peak in temperature near the substellar point that decreases steeply and symmetrically with longitude towards the terminators.

Evolutionary effects of nitrogen are not easily predicted from ecological responses.

PREMISE: Anthropogenic nitrogen (N) addition alters the abiotic and biotic environment, potentially leading to changes in patterns of natural selection (i.e., trait-fitness relationships) and the opportunity for selection (i.e., variance in relative fitness). Because N addition favors species with light acquisition strategies (e.g., tall species), we predicted that N would strengthen selection favoring those same traits. We also predicted that N could alter the opportunity for selection via its effects on mean fitness and/or competitive asymmetries. METHODS: We quantified the strength of selection and the opportunity for selection in replicated populations of the annual grass Setaria faberi (giant foxtail) growing in a long-term N addition experiment. We also correlated these population-level parameters with community-level metrics to identify the proximate causes of N-mediated evolutionary effects. RESULTS: N addition increased aboveground productivity, light asymmetry, and reduced species diversity. Contrary to expectations, N addition did not strengthen selection for trait values associated with higher light acquisition such as greater height and specific leaf area (SLA); rather, it strengthened selection favoring lower SLA. Light asymmetry and species diversity were associated with selection for height and SLA, suggesting a role for these factors in driving N-mediated selection. The opportunity for selection was not influenced by N addition but was negatively associated with species diversity. CONCLUSIONS: Our results indicate that anthropogenic N enrichment can affect evolutionary processes, but that evolutionary changes in plant traits within populations are unlikely to parallel the shifts in plant traits observed at the community level.

Contemporary evolution rivals the effects of rhizobium presence on community and ecosystem properties in experimental mesocosms.

Because genotypes within a species commonly differ in traits that influence other species, whole communities, or even ecosystem functions, evolutionary change within one key species may affect the community and ecosystem processes. Here we use experimental mesocosms to test how the evolution of reduced cooperation in rhizobium mutualists in response to 20 years of nitrogen fertilization compares to the effects of rhizobium presence on soil nitrogen availability and plant community composition and diversity. The evolution of reduced rhizobium cooperation caused reductions in soil nitrogen, biological nitrogen fixation, and leaf nitrogen concentrations that were as strong as, or even stronger than, experimental rhizobium inoculation (presence/absence) treatments. Effects of both rhizobium evolution and rhizobium inoculation on legume dominance, plant community composition, and plant species diversity were often smaller in magnitude, but suggest that rhizobium evolution can alter the relative abundance of plant functional groups. Our findings indicate that the consequences of rapid microbial evolution for ecosystems and communities can rival the effects resulting from the presence or abundance of keystone mutualists.

Bedtime media use and sleep: evidence for bidirectional effects and associations with attention control in adolescents.

OBJECTIVE/DESIGN: Bedtime media use has been associated with poor sleep and attention difficulties among adolescents, but much of this research has been cross-sectional, limiting current understanding of directionality of effects. This 2-wave prospective study tested bidirectional effects between bedtime media use and sleep measures, including time in bed, sleep onset latency, and daytime sleepiness, and further examined whether bedtime media use and sleep variables were related to attention control difficulties. SETTING/PARTICIPANTS: Data were collected from 345 middle-schoolers (ages 12-14, 47% female) at baseline (T1) and at 6-month follow-up (T2). MEASUREMENTS: Students self-reported their access to media devices and internet in their bedroom, bedtime media use, sleep, and attention control. Data were analyzed using cross-lagged panel modeling. RESULTS: Greater bedtime media use (at T1) was associated with less time in bed and longer sleep onset latency at T2, controlling for T1 levels of these variables. In the case of sleep effects on bedtime media use, greater daytime sleepiness and less time in bed (at T1) were associated with greater bedtime media use at T2, controlling for T1 levels. Further, greater daytime sleepiness (at T2, controlling for T1 levels) was associated with greater attention control difficulties at T2. CONCLUSIONS: Findings provide evidence for some reciprocal relations between bedtime media use and poor sleep in adolescents. Furthermore, higher daytime sleepiness was linked to greater attention control difficulties.

Vertically Resolved Magma Ocean-Protoatmosphere Evolution: H2, H2O, CO2, CH4, CO, O2, and N2 as Primary Absorbers.

The earliest atmospheres of rocky planets originate from extensive volatile release during magma ocean epochs that occur during assembly of the planet. These establish the initial distribution of the major volatile elements between different chemical reservoirs that subsequently evolve via geological cycles. Current theoretical techniques are limited in exploring the anticipated range of compositional and thermal scenarios of early planetary evolution, even though these are of prime importance to aid astronomical inferences on the environmental context and geological history of extrasolar planets. Here, we present a coupled numerical framework that links an evolutionary, vertically resolved model of the planetary silicate mantle with a radiative-convective model of the atmosphere. Using this method, we investigate the early evolution of idealized Earth-sized rocky planets with end-member, clear-sky atmospheres dominated by either H2, H2O, CO2, CH4, CO, O2, or N2. We find central metrics of early planetary evolution, such as energy gradient, sequence of mantle solidification, surface pressure, or vertical stratification of the atmosphere, to be intimately controlled by the dominant volatile and outgassing history of the planet. Thermal sequences fall into three general classes with increasing cooling timescale: CO, N2, and O2 with minimal effect, H2O, CO2, and CH4 with intermediate influence, and H2 with several orders of magnitude increase in solidification time and atmosphere vertical stratification. Our numerical experiments exemplify the capabilities of the presented modeling framework and link the interior and atmospheric evolution of rocky exoplanets with multiwavelength astronomical observations.

The rotational and divergent components of atmospheric circulation on tidally locked planets.

Tidally locked exoplanets likely host global atmospheric circulations with a superrotating equatorial jet, planetary-scale stationary waves, and thermally driven overturning circulation. In this work, we show that each of these features can be separated from the total circulation by using a Helmholtz decomposition, which splits the circulation into rotational (divergence-free) and divergent (vorticity-free) components. This technique is applied to the simulated circulation of a terrestrial planet and a gaseous hot Jupiter. For both planets, the rotational component comprises the equatorial jet and stationary waves, and the divergent component contains the overturning circulation. Separating out each component allows us to evaluate their spatial structure and relative contribution to the total flow. In contrast with previous work, we show that divergent velocities are not negligible when compared with rotational velocities and that divergent, overturning circulation takes the form of a single, roughly isotropic cell that ascends on the day side and descends on the night side. These conclusions are drawn for both the terrestrial case and the hot Jupiter. To illustrate the utility of the Helmholtz decomposition for studying atmospheric processes, we compute the contribution of each of the circulation components to heat transport from day side to night side. Surprisingly, we find that the divergent circulation dominates day-night heat transport in the terrestrial case and accounts for around half of the heat transport for the hot Jupiter. The relative contributions of the rotational and divergent components to day-night heat transport are likely sensitive to multiple planetary parameters and atmospheric processes and merit further study.

Adolescent measures of family socioeconomic status: Reliability, validity, and effects on substance use behaviors in adolescence and young adulthood.

Socioeconomic status (SES) is a robust predictor of health disparities in adolescence and early adulthood, yet obtaining accurate and reliable measurements of family SES from younger participants remains a challenge. We evaluated the reliability and validity of a subjective SES measure, i.e., perceived family financial security (PFS), which assesses adolescents' perceptions of whether their family has enough money to meet their needs. We also examined the predictive associations of PFS and parental education (adolescent reports) with alcohol, marijuana, and tobacco use during adolescence and young adulthood. Longitudinal data were obtained from 593 parent-child dyads in the Pacific Northwest region of the United States, who were assessed eight times between 2005 and 2014. Present analyses included data from four annual assessments conducted when the participating children were adolescents (age range = 10.25-16.33 years) and a final follow-up in young adulthood (age range = 20-23.42 years). PFS had good test-retest reliability and convergent validity with other parent and adolescent reported SES measures. Adolescent-reported PFS significantly predicted tobacco use frequency in young adulthood, whereas adolescent-reported parental education predicted alcohol use frequency. PFS was not a significant predictor of alcohol or marijuana use. Findings suggest that PFS can be a psychometrically sound measure to assess a unique dimension of SES in adolescent samples, with differential predictive associations among substance use outcomes in young adulthood compared to more traditional measures like parental education. Future research should evaluate the psychometric properties and utility of PFS as a complementary SES measure.

Trace vapor generator for Explosives and Narcotics (TV-Gen).

The Trace Vapor Generator for Explosives and Narcotics (TV-Gen) is a portable and compact instrument designed to deliver a continuous source of trace-level vapors and vapor mixtures. It provides a tool to assist in the independent validation and verification of new materials and sensors under development for the vapor detection of explosives and narcotics. The design was conceived for use with a broad range of analytes, detection systems, materials, and sensors and to switch easily between the clean and analyte vapor streams. The TV-Gen system utilizes nebulization of aqueous analyte solutions, an oven to promote efficient transport, and a control box that provides dedicated computer control with logging capabilities. Resultant vapor streams are stable over several hours, with the vapor concentration controlled by a combination of aqueous analyte solution concentration, liquid flow rate through the nebulizer, and volume flow rate of air through the TV-Gen manifold.

Modulation of the fungal mycobiome is regulated by the chitin-binding receptor FIBCD1.

Host-microbiota interactions are critical in regulating mammalian health and disease. In addition to bacteria, parasites, and viruses, beneficial communities of fungi (the mycobiome) are important modulators of immune- and tissue-homeostasis. Chitin is a major component of the fungal cell wall, and fibrinogen C containing domain 1 (FIBCD1) is a chitin-binding protein; however, the role of this molecule in influencing host-mycobiome interactions in vivo has never been examined. Here, we identify direct binding of FIBCD1 to intestinal-derived fungi and demonstrate that epithelial-specific expression of FIBCD1 results in significantly reduced fungal colonization and amelioration of fungal-driven intestinal inflammation. Collectively, these results identify FIBCD1 as a previously unrecognized microbial pattern recognition receptor through which intestinal epithelial cells can recognize and control fungal colonization, limit fungal dysbiosis, and dampen intestinal inflammation.

Evolving window factor analysis-multivariate curve resolution with automated library matching for enhanced peak deconvolution in gas chromatography-mass spectrometry fuel data.

Fuel chromatography is inherently limited by the high complexity of petroleum fuel compositions. In practice, almost no fuel components are fully resolved in gas chromatography. This is due to both insufficient peak capacity for the large number of individual components within time and chromatographic efficiency constraints, and insufficient resolving power of the stationary phase in the gas chromatography column relative to the many structurally similar isomers or homologs present in petrochemical fuels. Multidimensional approaches, longer columns and slower heating rates can offer some benefits but will not necessarily fully resolve co-eluting fuel compounds, especially within reasonable analysis times. The following work details how deconvolved mass spectral loadings, combined with library matching, provide a quality metric against which to automatically evaluate results obtained from an experimental evolving window factor analysis-multivariate curve resolution deconvolution algorithm applied to gas chromatography-mass spectrometry data. This algorithm was evaluated in the context of trace component detection in synthetic fuel data sets, dodecane and tetradecane detection in petrochemical fuels, and the detection of natural products unlikely to be present in petrochemical fuels. In the case of the trace component detection challenge, the experimental algorithm outperformed a control algorithm that utilized a singular value-based quality metric. Meanwhile, when detecting dodecane, tetradecane, and natural products in petrochemical fuels, the experimental algorithm allowed for higher-quality compound identification results than could be obtained without peak deconvolution, thus reliably improving fuel component resolution in an automated fashion.

FIBCD1 Binds Aspergillus fumigatus and Regulates Lung Epithelial Response to Cell Wall Components.

Aspergillus fumigatus (A. fumigatus) is a ubiquitous fungus of clinical importance associated with development of various pulmonary diseases and allergic hypersensitivity reactions. It is protected against environmental stress by a cell wall that contains polysaccharides such as chitin. We previously demonstrated that fibrinogen C domain-containing protein 1 (FIBCD1) is a membrane-bound protein that binds chitin through a conserved S1 binding site and is expressed in intestinal epithelium and salivary glands. Here, we further localized FIBCD1 protein expression at the surface of bronchial and alveolar human lung epithelium, observed recognition of A. fumigatus cell wall with S1 site-independent recognition. We observed FIBCD1-mediated suppression of IL-8 secretion, mucin production, and transcription of genes associated with airway inflammation and homeostasis in FIBCD1-transfected lung epithelial cells. These modulations were generally enforced by stimulation with A. fumigatus cell wall polysaccharides. In parallel, we demonstrated a FIBCD1-mediated modulation of IL-8 secretion induced by TLR2,-4, and -5. Collectively, our findings support FIBCD1 as a human lung epithelial pattern recognition receptor that recognizes the complex A. fumigatus cell wall polysaccharides and modulates the lung epithelial inflammatory response by suppressing inflammatory mediators and mucins.

Trace explosives sensor testbed (TESTbed).

A novel vapor delivery testbed, referred to as the Trace Explosives Sensor Testbed, or TESTbed, is demonstrated that is amenable to both high- and low-volatility explosives vapors including nitromethane, nitroglycerine, ethylene glycol dinitrate, triacetone triperoxide, 2,4,6-trinitrotoluene, pentaerythritol tetranitrate, and hexahydro-1,3,5-trinitro-1,3,5-triazine. The TESTbed incorporates a six-port dual-line manifold system allowing for rapid actuation between a dedicated clean air source and a trace explosives vapor source. Explosives and explosives-related vapors can be sourced through a number of means including gas cylinders, permeation tube ovens, dynamic headspace chambers, and a Pneumatically Modulated Liquid Delivery System coupled to a perfluoroalkoxy total-consumption microflow nebulizer. Key features of the TESTbed include continuous and pulseless control of trace vapor concentrations with wide dynamic range of concentration generation, six sampling ports with reproducible vapor profile outputs, limited low-volatility explosives adsorption to the manifold surface, temperature and humidity control of the vapor stream, and a graphical user interface for system operation and testing protocol implementation.

Analysis of ammonium nitrate headspace by on-fiber solid phase microextraction derivatization with gas chromatography mass spectrometry.

A novel analytical method has been developed for the quantitation of trace levels of ammonia in the headspace of ammonium nitrate (AN) using derivatized solid phase microextraction (SPME) fibers with gas chromatography mass spectrometry (GC-MS). Ammonia is difficult to detect via direct injection into a GC-MS because of its low molecular weight and extreme polarity. To circumvent this issue, ammonia was derivatized directly onto a SPME fiber by the reaction of butyl chloroformate coated fibers with the ammonia to form butyl carbamate. A derivatized externally sampled internal standard (dESIS) method based upon the reactivity of diethylamine with unreacted butyl chloroformate on the SPME fiber to form butyl diethylcarbamate was established for the reproducible quantification of ammonia concentration. Both of these compounds are easily detectable and separable via GC-MS. The optimized method was then used to quantitate the vapor concentration of ammonia in the headspace of two commonly used improvised explosive device (IED) materials, ammonium nitrate fuel oil (ANFO) and ammonium nitrate aluminum powder (Ammonal), as well as identify the presence of additional fuel components within the headspace.

Formulating powder-device combinations for salmeterol xinafoate dry powder inhalers.

Using salmeterol xinafoate (SX) as an active pharmaceutical ingredient, the effects of carrier lactose particle type, total lactose fines content and device resistance on dry powder inhaler performance were investigated in vitro. To mimic drug levels in commercial preparations, interactive mixtures containing 0.58% w/w SX were prepared by low shear tumble mixing. Three types of milled inhalation grade lactose were used (Lactohale(®) LH 200, Respitose(®) ML006 and ML001) and the concentration of fine lactose (Lactohale(®) 300) added was varied. The in vitro deposition of each mixture was studied using a next generation impactor and inhaler devices exhibiting different resistances, Rotahaler(®)80% ED and MMAD ± GSD between 1-5 µm. The results confirmed the factors under investigation to be important determinants of product performance, but demonstrated using realistic conditions how individual factor impact may be enhanced or mitigated by inter-dependency.

Continuous flow, explosives vapor generator and sensor chamber.

A novel liquid injection vapor generator (LIVG) is demonstrated that is amenable to low vapor pressure explosives, 2,4,6-trinitrotoluene and hexahydro-1,3,5-trinitro-1,3,5-triazine. The LIVG operates in a continuous manner, providing a constant and stable vapor output over a period of days and whose concentration can be extended over as much as three orders of magnitude. In addition, a large test atmosphere chamber attached to the LIVG is described, which enables the generation of a stable test atmosphere with controllable humidity and temperature. The size of the chamber allows for the complete insertion of testing instruments or arrays of materials into a uniform test atmosphere, and various electrical feedthroughs, insertion ports, and sealed doors permit simple and effective access to the sample chamber and its vapor.

Investigation of dry powder inhaler (DPI) resistance and aerosol dispersion timing on emitted aerosol aerodynamic particle sizing by multistage cascade impactor when sampled volume is reduced from compendial value of 4 L.

Compendial methods determining dry powder inhaler (DPI)-emitted aerosol aerodynamic particle size distribution (APSD) collect a 4-L air sample containing the aerosol bolus, where the flow, which propagates through the cascade impactor (CI) measurement system from the vacuum source, is used to actuate the inhaler. A previous article described outcomes with two CIs (Andersen eight-stage cascade impactor (ACI) and Next-Generation Pharmaceutical Impactor (NGI)) when the air sample volume was ≤4 L with moderate-resistance DPIs. This article extends that work, examining the hypothesis that DPI flow resistance may be a factor in determining outcomes. APSD measurements were made using the same CI systems with inhalers representing low and high flow resistance extremes (Cyclohaler® and HandiHaler® DPIs, respectively). The ratio of sample volume to internal dead space (normalized volume (V*)) was varied from 0.25 to 1.98 (NGI) and from 0.43 to 3.46 (ACI). Inhaler resistance was a contributing factor to the rate of bolus transfer; the higher resistance DPI completing bolus relocation to the NGI pre-separator via the inlet when V* was as small as 0.25, whereas only ca. 50% of the bolus mass was collected at this condition with the Cyclohaler® DPI. Size fractionation of the bolus from either DPI was completed within the ACI at smaller values of V* than within the NGI. Bolus transfer from the Cyclohaler® capsule and from the HandiHaler® to the ACI system were unaffected by the different flow rise time observed in the two different flow controller systems, and the effects the ACI-based on APSD measurements were marginal.

Endogenous cholinergic tone modulates spontaneous network level neuronal activity in primary cortical cultures grown on multi-electrode arrays.

BACKGROUND: Cortical cultures grown long-term on multi-electrode arrays (MEAs) are frequently and extensively used as models of cortical networks in studies of neuronal firing activity, neuropharmacology, toxicology and mechanisms underlying synaptic plasticity. However, in contrast to the predominantly asynchronous neuronal firing activity exhibited by intact cortex, electrophysiological activity of mature cortical cultures is dominated by spontaneous epileptiform-like global burst events which hinders their effective use in network-level studies, particularly for neurally-controlled animat ('artificial animal') applications. Thus, the identification of culture features that can be exploited to produce neuronal activity more representative of that seen in vivo could increase the utility and relevance of studies that employ these preparations. Acetylcholine has a recognised neuromodulatory role affecting excitability, rhythmicity, plasticity and information flow in vivo although its endogenous production by cortical cultures and subsequent functional influence upon neuronal excitability remains unknown. RESULTS: Consequently, using MEA electrophysiological recording supported by immunohistochemical and RT-qPCR methods, we demonstrate for the first time, the presence of intrinsic cholinergic neurons and significant, endogenous cholinergic tone in cortical cultures with a characterisation of the muscarinic and nicotinic components that underlie modulation of spontaneous neuronal activity. We found that tonic muscarinic ACh receptor (mAChR) activation affects global excitability and burst event regularity in a culture age-dependent manner whilst, in contrast, tonic nicotinic ACh receptor (nAChR) activation can modulate burst duration and the proportion of spikes occurring within bursts in a spatio-temporal fashion. CONCLUSIONS: We suggest that the presence of significant endogenous cholinergic tone in cortical cultures and the comparability of its modulatory effects to those seen in intact brain tissues support emerging, exploitable commonalities between in vivo and in vitro preparations. We conclude that experimental manipulation of endogenous cholinergic tone could offer a novel opportunity to improve the use of cortical cultures for studies of network-level mechanisms in a manner that remains largely consistent with its functional role.

Genetic architecture of flowering time differentiation between locally adapted populations of Arabidopsis thaliana.

To gain an understanding of the genetic basis of adaptation, we conducted quantitative trait locus (QTL) mapping for flowering time variation between two winter annual populations of Arabidopsis thaliana that are locally adapted and display distinct flowering times. QTL mapping was performed with large (n = 384) F(2) populations with and without vernalization, in order to reveal both the genetic basis of a vernalization requirement and that of variation in flowering time given vernalization. In the nonvernalization treatment, none of the Sweden parents flowered, whereas all of the Italy parents and 42% of the F(2)s flowered. We identified three QTLs for flowering without vernalization, with much of the variation being attributed to a QTL co-localizing with FLOWERING LOCUS C (FLC). In the vernalization treatment, all parents and F(2)s flowered, and six QTLs of small to moderate effect were revealed, with underlying candidate genes that are members of the vernalization pathway. We found no evidence for a role of FRIGIDA in the regulation of flowering times. These results contribute to a growing body of evidence aimed at the identification of ecologically relevant genetic variation for flowering time in Arabidopsis, and set the stage for functional studies to determine the link between flowering time loci and fitness.

Effect of sampling volume on dry powder inhaler (DPI)-emitted aerosol aerodynamic particle size distributions (APSDs) measured by the Next-Generation Pharmaceutical Impactor (NGI) and the Andersen eight-stage cascade impactor (ACI).

Current pharmacopeial methods for testing dry powder inhalers (DPIs) require that 4.0 L be drawn through the inhaler to quantify aerodynamic particle size distribution of "inhaled" particles. This volume comfortably exceeds the internal dead volume of the Andersen eight-stage cascade impactor (ACI) and Next Generation pharmaceutical Impactor (NGI) as designated multistage cascade impactors. Two DPIs, the second (DPI-B) having similar resistance than the first (DPI-A) were used to evaluate ACI and NGI performance at 60 L/min following the methodology described in the European and United States Pharmacopeias. At sampling times ≥2 s (equivalent to volumes ≥2.0 L), both impactors provided consistent measures of therapeutically important fine particle mass (FPM) from both DPIs, independent of sample duration. At shorter sample times, FPM decreased substantially with the NGI, indicative of incomplete aerosol bolus transfer through the system whose dead space was 2.025 L. However, the ACI provided consistent measures of both variables across the range of sampled volumes evaluated, even when this volume was less than 50% of its internal dead space of 1.155 L. Such behavior may be indicative of maldistribution of the flow profile from the relatively narrow exit of the induction port to the uppermost stage of the impactor at start-up. An explanation of the ACI anomalous behavior from first principles requires resolution of the rapidly changing unsteady flow and pressure conditions at start up, and is the subject of ongoing research by the European Pharmaceutical Aerosol Group. Meanwhile, these experimental findings are provided to advocate a prudent approach by retaining the current pharmacopeial methodology.

Emergence of a small-world functional network in cultured neurons.

The functional networks of cultured neurons exhibit complex network properties similar to those found in vivo. Starting from random seeding, cultures undergo significant reorganization during the initial period in vitro, yet despite providing an ideal platform for observing developmental changes in neuronal connectivity, little is known about how a complex functional network evolves from isolated neurons. In the present study, evolution of functional connectivity was estimated from correlations of spontaneous activity. Network properties were quantified using complex measures from graph theory and used to compare cultures at different stages of development during the first 5 weeks in vitro. Networks obtained from young cultures (14 days in vitro) exhibited a random topology, which evolved to a small-world topology during maturation. The topology change was accompanied by an increased presence of highly connected areas (hubs) and network efficiency increased with age. The small-world topology balances integration of network areas with segregation of specialized processing units. The emergence of such network structure in cultured neurons, despite a lack of external input, points to complex intrinsic biological mechanisms. Moreover, the functional network of cultures at mature ages is efficient and highly suited to complex processing tasks.