Small Shift Research Articles

Climatic niche and range shifts of grey squirrels (Sciurus carolinensis Gmelin) in Europe: An invasive pest displacing native squirrels.

As an invasive pest from North America, grey squirrels (GSs; Sciurus carolinensis Gmelin) are displacing native squirrels in Europe. However, the climatic niche and range dynamics of GSs in Europe remain largely unknown. Through niche and range dynamic models, we investigated climatic niche and range shifts between introduced GSs in Europe and native GSs in North America. GSs in North America can survive in more variable climatic conditions and have much wider climatic niche breadth than do GSs in Europe. Based on climate, the potential range of GSs in Europe included primarily Britain, Ireland, and Italy, whereas the potential range of GSs in North America included vast regions of western and southern Europe. If GSs in Europe could occupy the same climatic niche space and potential range as GSs in North America, they would occupy an area ca. 2.45 times the size of their current range. The unfilling ranges of GSs in Europe relative to those of GSs in North America were primarily in France, Italy, Spain, Croatia, and Portugal. Our observations implied that GSs in Europe have significant invasion potential, and that range projections based on their occurrence records in Europe may underestimate their invasion risk. Given that small niche shifts between GSs in Europe and in North America could lead to large range shifts, niche shifts could be a sensitive indicator in invasion risk assessment. The identified unfilling ranges of the GS in Europe should be prioritized in combating GS invasions in the future. © 2023 Society of Chemical Industry.

0179 Mathematical Models to Predict Sleep Latency and Sleep Duration

Abstract Introduction The demands of a 24/7 society prevent millions of shift workers around the world from obtaining regular nightly sleep, negatively affecting their health, safety, and productivity. To mitigate this problem, workers should maximize the benefits of their atypical sleep opportunities. This requires assessing the ability of an individual to initiate and maintain sleep at the intended time, given their recent sleep history. Here, we present two validated mathematical models, one for predicting sleep latency and a second for predicting sleep duration, as decision aids for planning effective sleep schedules that maximize restorative sleep. Methods As an extension of the two-process model of sleep regulation, the proposed models predict sleep latency and sleep duration by accounting for the nonlinear interactions between homeostatic sleep pressure and the circadian rhythm. We estimated the models’ parameter values for a population of young, healthy adults using experimental data from two studies and validated the models by comparing their predictions with experimental measurements from 22 different studies, involving a variety of sleep conditions spanning the entire circadian cycle and a total of 317 unique subjects. Results Comparison of the sleep-latency and sleep-duration models’ predictions with the experimental data showed that the models yielded acceptable average prediction errors: 4.0 minutes for sleep latency and 0.8 hours for sleep duration. Importantly, we identified conditions under which small shifts in bedtime may result in disproportionately large differences in sleep duration--knowledge that may be applied to improve productivity, safety, and sustainability in civilian and military operations. Conclusion By extending the capabilities of existing predictive fatigue-management tools, the mathematical models described here allow users to determine the most opportune times to sleep. This information can be used to optimize sleep efficiency, allowing shift workers to maximize the benefits of restorative sleep. Support (if any)

Improved chi-square control charts with weak-run rules

The chi-square control chart is one of the most popular multivariate charting techniques for monitoring the vector of means of several quality characteristics. During the last decades, runs rules have been supplemented in the design of the chi-square control chart and they have significantly improved its performance. In this article, we introduce and study a chi-square control chart with supplementary weak-run rules, which improves the chart’s detection capability in the case of small and moderate process mean vector shifts. Our study also establishes new theoretical results regarding the waiting time for the first occurrence of an r-weak run in a sequence of binary trials.

Effect of B-site substitution on the luminescence, thermal stability and temperature sensitivity of Ba2NaNb5O15:Eu3+/Er3+ glass ceramics

Transparent glass ceramic with Ba2NaNb5O15 as the main crystal phase was prepared, and the appropriate heat treatment condition was selected as 710 °C/150 min through various characterizations. The luminous intensity and thermal stability were enhanced significantly when the glass ceramic was used as the luminous matrix. After introducing Ti4+ ions as charge compensators, the luminescence performance and thermal stability were further improved, and the reasons for this were analyzed. At 458 K, the luminous intensity of 0.5%Eu3+ doped glass ceramic containing 0.5%Ti4+ can maintain about 65% of room temperature with a chromaticity shift of 5.16 × 10−2. The relative and absolute sensitivities of 0.7%Er3+ doped glass ceramic were 4.04 × 10−3 K−1 and 1.31% K−1. Introducing Ti4+ ions would weaken the population redistribution ability of 2H11/2 and 4S3/2 levels and reduce the temperature sensitivity. However, the sample containing Ti4+ shows good thermal stability, its green emission at 458 K has a small chromaticity shift of 6.45 × 10−3. The research shows that the glass ceramic can be used as a good luminescent host material, and Eu3+/Er3+ doped glass ceramic can be used in the fields of LEDs or temperature sensing.

Controlled Nanoplatelet Deposition of 2D Chromium Trihalide Solid Solutions

The two-dimensional (2D) chromium trihalides CrCl3, CrBr3, and CrI3 are most famous for their exotic magnetic properties when their crystals get downscaled to nanometer dimensions. One way to tune the properties of such materials and to further increase their potential utility, e.g., in spintronics, is the formation of solid solutions. Here, we present a detailed theoretical and experimental study on the synthesis and nanoplatelet growth of CrBrxCl3–x and CrBrxI3–x solid solutions. Phase pure powder was obtained by tempering the respective parent compounds at 600 and 550 °C, using additional iodine in the case of CrBrxI3–x. The dominant stacking order changes at x = 1.8 for CrBrxCl3–x while remaining similar to CrI3 for the whole CrBrxI3–x series. A consecutive chemical vapor transport from 575 → 525 °C for 2 h (CrBrxCl3–x) or 600 → 550 °C for 3 h with 0.1 mmol additional iodine (CrBrxI3–x) resulted in the deposition of high-quality nanoplatelets on a substrate with only several nanometers in height. The composition can be controlled by the choice of the starting material, since only small shifts in the anion ratio occur during the transport. The deposited CrBrxCl3–x nanoplatelets can then be easily delaminated by ultrasonication in ethanol to reduce the height even further to few-layer dimensions. These nanoplatelets could potentially be used to investigate the property changes (e.g., in terms of magnetic response) for the downscaling of these solid solutions. We further demonstrate the quality of the deposited material by transmission electron microscopy, selected area electron diffraction, and X-ray photoelectron spectroscopy. Raman spectroscopy of the solid solution series reveals a complex evolution of vibrational modes. Photoluminescence measurements on solid solution samples show emission peaks in the near-infrared energy range with the specific energy and intensity being composition and temperature dependent.

Civil society priorities forglobal health: concepts andmeasurement.

The global health agenda-a high stakes process in which problems are defined and compete for the kind of serious attention that promises to help alleviate inequities in the burden of disease-is comprised of priorities set within and among a host of interacting stakeholder arenas. This study informs crucial and unanswered conceptual and measurement questions with respect to civil society priorities in global health. The exploratory two-stage inquiry probes insights from experts based in four world regions and pilots a new measurement approach, analysing nearly 20 000 Tweets straddling the COVID-19 pandemic onset from a set of civil society organizations (CSOs) engaged in global health. Expert informants discerned civil society priorities principally on the basis of observed trends in CSO and social movement action, including advocacy, programme, and monitoring and accountability activities-all of which are widely documented by CSOs active on Twitter. Systematic analysis of a subset of CSO Tweets shows how their attention to COVID-19 soared amidst mostly small shifts in attention to a wide range of other issues between 2019 and 2020, reflecting the impacts of a focusing event and other dynamics. The approach holds promise for advancing measurement of emergent, sustained and evolving civil society priorities in global health.

Optical telecommunications-band clock based on neutral titanium atoms

We propose an optical clock based on narrow, spin-forbidden M1 and E2 transitions in laser-cooled neutral titanium. These transitions exhibit much smaller black body radiation shifts than those in alkaline earth atoms, small quadratic Zeeman shifts, and have wavelengths in the S, C, and L-bands of fiber-optic telecommunication standards, allowing for integration with robust laser technology. We calculate lifetimes; transition matrix elements; dynamic scalar, vector, and tensor polarizabilities; and black body radiation shifts of the clock transitions using a high-precision relativistic hybrid method that combines a configuration interaction and coupled cluster approaches. We also calculate the line strengths and branching ratios of the transitions used for laser cooling. To identify magic trapping wavelengths, we have completed the largest-to-date direct dynamical polarizability calculations. Finally, we identify new challenges that arise in precision measurements due to magnetic dipole-dipole interactions and describe an approach to overcome them. Direct access to a telecommunications-band atomic frequency standard will aid the deployment of optical clock networks and clock comparisons over long distances.

A Web-Based Public Health Intervention for Addressing Vaccine Misinformation: Analysis of Learner Engagement and Shift in Hesitancy to Vaccinate.

Web-based public health interventions can be a useful tool for disseminating evidence-based information to the public. However, completion rates are traditionally low, and misinformation often travels at a faster pace than evidence-based sources. This study describes the design of a web-based public health intervention to address COVID-19 vaccine hesitancy. A quasi-experimental approach was used in which a validated instrument, the Adult Vaccine Hesitancy Survey, was given to learners both pre and post intervention to observe any change in attitude towards vaccination. Our pilot observed a small positive shift in vaccine hesitancy and experienced higher than average completion rates. By integrating motivational learning design into public health interventions we increase the likelihood that learners finish the entire intervention, creating greater chance for positive behavior change.

Land–Sea Distribution of Ground Precipitation in Mediterranean Storms

The Mediterranean basin is traditionally a hotspot where copious amounts of water vapor at low- and mid-tropospheric levels often favor atmospheric instability and the deepening of storms, leading to intense rainfall events with consequent flash floods. Moreover, this region includes sharp land–sea transitions, narrow maritime areas, and mountain chains which enhance convective precipitation. In this study, radar precipitation data were used to investigate the spatial distribution of rainfall swaths for seven severe cyclones originating over the Mediterranean Sea which produced intense flash inundation events along the western coast of Italy in the last decade (2011–2020). Based on 5 min precipitation amounts gridded at a 1 km spatial resolution, the temporal evolution of these storms displays a curvilinear path moving from sea to inland. Results show that more than half of the total precipitation for the analyzed events occurred on sea, and the total amount of storm rainfall over the marine surface exceeded that over land in four events out of the seven. Since the coastline strongly affects the rainfall pattern, we analyzed the land–sea discontinuity, which is a key factor controlling the spatial distribution of storm rates through their trajectory, where a small shift in precipitation target might smooth ground effects and mitigate flood impacts.

Self-wavelength shifting in two-dimensional perovskite for sensitive and fast gamma-ray detection

Lead halide perovskites have recently emerged as promising X/γ-ray scintillators. However, the small Stokes shift of exciton luminescence in perovskite scintillators creates problems for the light extraction efficiency and severely impedes their applications in hard X/γ-ray detection. Dopants have been used to shift the emission wavelength, but the radioluminescence lifetime has also been unwantedly extended. Herein, we demonstrate the intrinsic strain in 2D perovskite crystals as a general phenomenon, which could be utilized as self-wavelength shifting to reduce the self-absorption effect without sacrificing the radiation response speed. Furthermore, we successfully demonstrated the first imaging reconstruction by perovskites for application of positron emission tomography. The coincidence time resolution for the optimized perovskite single crystals (4 × 4 × 0.8 mm3) reached 119 ± 3 ps. This work provides a new paradigm for suppressing the self-absorption effect in scintillators and may facilitate the application of perovskite scintillators in practical hard X/γ-ray detections.

On designing new mixed modified exponentially weighted moving average - exponentially weighted moving average control chart

Control charts are an extremely valuable tool in statistical process control (SPC) for processing information from a system or procedure over time and displaying statistically significant changes in data while also showing how a system or process is changing. The modified exponentially weighted moving average - exponentially weighted moving average control chart (MEME) is proposed as a new mixed control chart for monitoring and quickly detecting moderate to small shifts in the mean process. Average and median run lengths are instruments for assessing efficiency through Monte Carlo simulations based on symmetric and nonsymmetric distributions. The performance comparison showed that the proposed chart outperformed alternatives control chart in simulation and in two real-data applications by lowering the out-of-control average run length.

Unraveling Ultralong Phosphorescence in Ar2PO(H): n(O) → σ*(P-C) Transitions in Ar2PO(H) Stabilize Triplet States Better than n(P) → σ*(P-C) in Ar3P

Herein, we report the crystallization-induced persistent room-temperature phosphorescence (CIpRTP) characteristics of simple diarylphosphine oxides 1, 2, and 3. Under ambient conditions, crystalline solids of 1, 2, and 3 show photoluminescence (PL) lifetime of more than 100 ms. At 77 K, they exhibit a PL lifetime of nearly a second. Replacing one of the aryl moieties in Ar3P═O with hydrogen creates more space for intermolecular interactions in Ar2P═O (H); consequently, the latter shows better PL quantum yield (PLQY) than the former. The PLQYs of these compounds are tuned systematically by varying the steric perturbation around the phosphorus center. Detailed analysis of the crystal structure of these compounds revealed that the intermolecular interactions play a crucial role in stabilizing the triplet state in the solid state and bestowing them with CIpRTP. Thin films of these compounds do not show pRTP, further affirming that the intermolecular interactions indeed play a crucial role in stabilizing the triplet state. In the solution state, these compounds show ultraviolet fluorescence (λem ≈ 305 nm) with a small Stokes shift of ∼3200 cm–1 and narrow bandwidth (FWHM: 37, 35, and 33 nm for 1, 2, and 3, respectively). The calculated SOC (⟨T1|Ĥ|S0⟩) matrix element for 1, 2, and 3 is significantly lower than the value estimated for triarylphosphines; thus, the former show ultralong phosphorescence compared to the latter. Furthermore, the n(O) → σ*(P-C) transition plays a crucial role in controlling the optical features in these compounds.

Thermally-stable novel NaBaBi2(PO4)3: Sm3+/Dy3+ white phosphors with tunable photoluminescence

The novel phosphors NaBaBi2(PO4)3: xDy3+ and NaBaBi2(PO4)3: 0.07Dy3+, ySm3+ were successfully synthesized using solid-state reaction method, and their microstructure, optical features and electroluminescent properties were studied. The experimental results show that the doping of Dy3+ exhibits strong yellow light emission, while Sm3+ can effectively compensate for the absent red emission in the Dy3+ emission spectrum, realize the color transition from yellow to white. In addition, the energy transfer process from Dy3+ to Sm3+ in NaBaBi2(PO4)3 was studied in details, and the light color can be adjusted by changing the ratio of Dy3+ and Sm3+, and the color temperature associated with NaBaBi2(PO4)3: 0.07Dy3+, ySm3+ can be adjusted from cool to natural. XRD and refinement results showed that Dy3+ and Sm3+ were successfully incorporated into the matrix. The morphology of NBBP: 0.07Dy3+, 0.05Sm3+ was characterized by SEM. The band gap of the NaBaBi2(PO4)3 matrix is calculated as a direct band gap by the density functional theory method, and the theoretical value (3.9534 eV) of the band gap is very similar to the experimental value (3.965 eV). By analyzing the total density of states and partial density of states, the valence band of the host is mainly composed of [PO4]. In addition, the NaBaBi2(PO4)3: 0.07Dy3+, 0.05Sm3+ phosphors have an energy transfer efficiency of 73% and exhibit excellent thermal stability, the fluorescence intensity at 428 K still maintains 81.79% of that at 303 K and has a small chromaticity shift. The correlated color temperature of the W-LEDs packaged with NaBaBi2(PO4)3: 0.07Dy3+, 0.05Sm3+ phosphor was measured as 4434K, and the color coordinates were measured as (0.3594, 0.3454). The W-LEDs driven at 3.4 V voltage and 600 mA current maintained its performance for 70 min, indicating that the packaged W-LEDs can operate continuously at high temperatures.

Demographic Characteristics Associated With Perceptions of Personal Utility in Genetic and Genomic Testing

The expansion of genetic and genomic testing in health care has led to recognition that these tests provide personal as well as clinical utility to patients and families. However, available systematic reviews on this topic have not reported the demographic backgrounds of participants in studies of personal utility, leaving generalizability unclear. To determine the demographic characteristics of participants in studies examining the personal utility of genetic and genomic testing in health care. For this systematic review, we utilized and updated the results of a highly cited 2017 systematic review on the personal utility of genetics and genomics, which identified relevant articles published between January 1, 2003, and August 4, 2016. We also used the original methods to update this bibliography with literature published subsequently up to January 1, 2022. Studies were screened for eligibility by 2 independent reviewers. Eligible studies reported empirical data on the perspectives of patients, family members, and/or the general public in the US on the personal utility of any type of health-related genetic or genomic test. We utilized a standardized codebook to extract study and participant characteristics. We summarized demographic characteristics descriptively across all studies and by subgroup based on study and participant characteristics. We included 52 studies with 13 251 eligible participants. Sex or gender was the most frequently reported demographic characteristic (48 studies [92.3%]), followed by race and ethnicity (40 studies [76.9%]), education (38 studies [73.1%]), and income (26 studies [50.0%]). Across studies, participants disproportionately were women or female (mean [SD], 70.8% [20.5%]), were White (mean [SD], 76.1% [22.0%]), had a college degree or higher (mean [SD], 64.5% [19.9%]), and reported income above the US median (mean [SD], 67.4% [19.2%]). Examination of subgroups of results by study and participant characteristics evidenced only small shifts in demographic characteristics. This systematic review examined the demographic characteristics of individual participants in studies of the personal utility of health-related genetic and genomic testing in the US. The results suggest that participants in these studies were disproportionately White, college-educated women with above-average income. Understanding the perspectives of more diverse individuals regarding the personal utility of genetic and genomic testing may inform barriers to research recruitment and uptake of clinical testing in currently underrepresented populations.

Amplified cortical neural responses as animals learn to use novel activity patterns

Cerebral cortex supports representations of the world in patterns of neural activity, used by the brain to make decisions and guide behavior. Past work has found diverse, or limited, changes in the primary sensory cortex in response to learning, suggesting that the key computations might occur in downstream regions. Alternatively, sensory cortical changes may be central to learning. We studied cortical learning by using controlled inputs we insert: we trained mice to recognize entirely novel, non-sensory patterns of cortical activity in the primary visual cortex (V1) created by optogenetic stimulation. As animals learned to use these novel patterns, we found that their detection abilities improved by an order of magnitude or more. The behavioral change was accompanied by large increases in V1 neural responses to fixed optogenetic input. Neural response amplification to novel optogenetic inputs had little effect on existing visual sensory responses. A recurrent cortical model shows that this amplification can be achieved by a small mean shift in recurrent network synaptic strength. Amplification would seem to be desirable to improve decision-making in a detection task; therefore, these results suggest that adult recurrent cortical plasticity plays a significant role in improving behavioral performance during learning.

Design of a narrow-band blue-emitting Rb2Ba3(P2O7)2:Eu2+ phosphor with low thermal quenching for plant growth LEDs

Phosphor-converted light-emitting diodes (pc-LEDs) are commonly used to regulate the light environment to control the growth rates and improve the production efficiency of plant. Among them, the exploration of blue-emitting phosphors with high efficiency, low thermal quenching and excellent spectrum resemblance matching with the plant response spectrum is still challenging. Herein, a narrow-band blue-emitting Rb2Ba3(P2O7)2:Eu2+ phosphor with high color purity of 93.4% has been developed. Under 345 nm excitation, it exhibits a blue emission band centered at 413 nm with a full width at half-maximum (FWHM) of 36 nm, and the emission spectrum of Rb2Ba3(P2O7)2:0.060Eu2+ sample shows 85.7% spectrum resemblance with the absorption spectrum of chlorophyll-a in the blue region from 400 to 500 nm. In addition, the temperature-dependent emission spectra demonstrate that the Rb2Ba3(P2O7)2:0.060Eu2+ phosphor has good thermal stability and small chromaticity shift, with the emission intensity dropping to 72.5% at 423 K of the initial intensity at 298 K and a chromaticity shift of 38 × 10-3 at 498 K. All results suggest that the blue-emitting Rb2Ba3(P2O7)2:Eu2+ phosphor has potential application in plant growth LEDs.

PENERAPAN DIAGRAM PENGENDALI NONPARAMETRIK EXPONENTIALLY WEIGHTED MOVING AVERAGE SIGN UNTUK ANALISIS PERGERAKAN HARGA SAHAM SEKTOR PROPERTI

Stocks are evidence of equity participation in a company. Investors need to know the quality of stock prices so that they can minimize losses when investing. Technical analysis can be used by investors to decide when to buy or sell a stock. One of the technical analysis that can be used on stock prices is using quality control. Control charts can be used to make decisions in stock trading activities. The Exponentially Weighted Moving Average control chart is very useful for detecting small shifts such as in financial data. The assumption that must be fulfilled in using the EWMA control chart is that the data is normally distributed. The non-fulfillment of the normal distribution assumption causes the EWMA control chart produces plots that are far from the control limits. This problem can be solved using the nonparametric EWMA Sign control chart. The construction of the nonparametric EWMA Sign control chart on stock prices is expected to overcome the limitations of the standard EWMA control chart and provide a signal to investors to know the best time to trade stocks. The data used in this study is the daily closing price data of PT Bumi Serpong Damai Tbk on March 1, 2021 to March 4, 2022 with a total of 250 data. The nonparametric EWMA Sign control chart shows that the daily closing price data is out of control because it produces plots that are spread out non-randomly and shows a relatively similar pattern.

PENERAPAN METODE POISSON EXPONENTIALLY WEIGHTED MOVING AVERAGE (PEWMA) UNTUK MEMBUAT BAGAN PENGENDALI VARIABEL BERDISTRIBUSI POISSON

Airplane is a mode of transportation that has an accident risk. Aircraft accidents are recorded to occur almost every year in Indonesia. The Poisson distribution is used to model the number of aircraft accidents that occur each year because they have a fixed time and independent. Statistical quality control is applied as a method to monitor the number of fatal aircraft accidents in Indonesia that are within control limits. One method to carry out quality control is to use a control chart. This study aims to apply the Poisson Exponentially Weighted Moving Average (PEWMA) method to create a control chart with a case study of the number of fatal airplane accidents in Indonesia from 1962 to 2021 with a Poisson distribution. The EWMA control chart is used to monitor the average or process variability and is considered effective in detecting small shifts in the process (the shift is said to be small if the shift is less than 1.5σ). The calculation of Average Run Length (ARL) is performed to test the performance of the PEWMA control chart. Control charts with smaller out-of-control ARLs are considered superior and can detect process shifts more quickly than other control charts. Based on the results of the calculation of the ARL value, it was found that the weight of 0.3 is the optimal weight with the smallest ARL value of 1.138 which is able to describe the state of the data on fatal aircraft accidents in Indonesia. The control chart with the optimal weight shows the data on fatal aircraft accidents in Indonesia that are tolerated equal to one.

Detection and mitigation of GPS Spoofing Attacks on Phasor Measurement Units using deep learning

The widespread use of Phasor Measurement Units (PMUs) is considered one of the most important contributions to the quality of power system monitoring. PMUs are digital devices that provide synchronized phasor measurements time-referenced by the Global Positioning System (GPS). The lack of encryption in conventional GPS receivers used in PMUs makes them vulnerable to GPS Spoofing Attacks (GSAs) that cause the GPS receiver to lose track, resulting in a phase shift of all measurements of the affected PMU. Even small phase shifts can downgrade the performance of the state estimator, indicating their ability to propagate throughout the entire system. Therefore, ensuring the integrity of PMU measurements is of utmost importance. State-of-the-art statistical methods are insensitive to small phase shifts, and they become computationally intensive as the system size and the number of simultaneous attacks increase. This paper presents the first application of deep learning to simultaneously detect and mitigate the effects of GSAs against PMUs. The performance of the proposed method is evaluated on IEEE 14-, 57-, and 118-bus systems and compared to state-of-the-art statistical and deep learning methods.

B cells regulate luminal bile acid composition in the small intestine

Abstract Recent studies have demonstrated that bile acids (BA) influence immune cell homeostasis in the gut. However, whether and how, the host immune response can influence BA biochemistry is unknown. This is an important question to answer because small shifts in BA composition in the gut can have significant pathophysiological consequences. Previously, we have demonstrated that CD19 −/−mice, which have a defect in B cell activation and consequently an aberrant humoral immune response, develop a small intestine (SI) enteropathy that is associated with abnormal luminal BA composition. However, CD19 −/−mice are not B-cell-deficient and present with multiple aberrant immune phenotypes. Here, we used B cell-deficient JHminus;/minus; mice to more effectively define this interaction. Results of our experiments provide three key observations. First, J H−/−mice develop altered SI BA pools compared to their WT littermates. Second, adoptive transfer of WT B cells into neonatal J H−/−mice led to the development of normal BA pools and rescued mice from SI enteropathy. Third, adoptive transfer of B cells incapable of secreting IgA into neonatal J H−/−mice failed to restore normal bile acid composition and only moderately protected animals from developing SI enteropathy. Collectively, the results of our experiments clearly demonstrate that B cells regulate bile acid composition in the SI and that the synthesis of mucosal IgA may be particularly important for driving this effect.