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Fabrication of PbSe quantum dot based flexible photodetector device arrays
Near-infrared spectroscopic detection has attracted great attention due to its extensive applications in various fields. Colloidal quantum dots exhibit significant potential for flexible and large-scale manufacturing, owing to their distinctive optoelectronic properties and versatile preparation methods. The present work investigates the synthesis of PbSe colloidal quantum dots via the thermal injection method and their application in the fabrication of photoconductive detector arrays. The effect of two different short-chain ligands [1, 2-ethanedithiol (EDT) and tetrabutylammonium iodide] on infrared detector performance is investigated, and it is found that EDT is better for improving device performance. Large-area electrode arrays were fabricated on flexible polyethylene terephthalate substrates using an inkjet deposition process. The cut-off wavelength of this detector is 0.71 eV, exhibiting excellent optical response in the visible-near-infrared range. The devices achieve a sensitivity of 9 A/W and a normalized detectivity of 6.5 × 1012 Jones under illumination from a 1550 nm laser light source. This study underscores the potential of PbSe quantum dots for advanced large-area photodetector arrays in infrared detection.
Spin dynamics of thiophene-fused π-systems with delayed emission
Triplet excited states in organic molecules are generally optically inactive due to spin-forbidden transitions to the singlet ground state. Recent studies have extensively investigated triplet states to circumvent limitations imposed by spin statistics in organic light-emitting diodes. Room-temperature electrophosphorescence and electrofluorescence have previously been observed in thienyl-substituted phenazines without heavy metals; however, phosphorescence was absent when spin density was localized on the thiophene units, despite the expected heavy-atom effect from the sulfur atom. In this study, we investigate the spin dynamics of thiophene-fused π-systems lacking phenazine units to enable the effective utilization of triplet states in thiophene-containing π-systems. This investigation reveals delayed emission in the excited dimers of fused thiophenes, likely associated with triplet–triplet annihilation. Optical and EPR measurements, together with quantum chemical calculations, indicate that the fused thiophenes form head-to-tail dimers in both the ground and excited states.
How to promote university technology transfer? A configuration analysis based on technology, organization and environment framework
University technology transfer (UTT) is at the forefront of innovation, representing the key to promoting the deep integration of science and technology with the economy. In order to explore mechanisms of realizing UTT, this study uses the fuzzy set qualitative comparative analysis (Fs-QCA) method to determine how the conditional configurations of technology, organization and environment (TOE) promote UTT. Evidently, there are four conditional configurations for promoting UTT, which are characterized by technology-organization-environment synergy, an organization-environment-orientation and a technology-organization-orientation. Technology transfer talents, organization construction, organization incentives, and market demand have an important influence on UTT. The main contribution of this study is its analysis of the nonlinear relationship between TOE conditions and UTT, which helps realize UTT in several ways.
Cartesian multipole expansion for millimeter-wave metasurfaces design
Metasurfaces in the microwave and millimeter-wave frequency ranges are conventionally designed through trial-and-error approaches using full-wave electromagnetic simulation packages that rely on discretization techniques to numerically solve differential equations. Although some studies in the literature propose semi-analytical approaches to improve design efficiency, a purely analytical framework remains elusive. Here, we apply the multipole expansion method, a classic approach from electromagnetism courses typically used for isolated scatterers, which has recently gained attention in the field of nanophotonics. In contrast to nanophotonics, where precise modeling requires detailed permittivity information, metals at microwave and millimeter-wave frequencies exhibit negligible penetration depths and limited electromagnetic–matter interaction. This simplification allows us to focus on conduction currents alone (given σ≫ωε) to describe the material’s response. Notably, we show that only four non-zero multipole terms are needed to achieve high accuracy in reproducing full-wave electromagnetic simulations, with results that also exhibit excellent qualitative agreement with experimental data.
Shaping membrane vesicles by tuning the activity of confined active polymer chains
Semi-flexible polymers, such as actin filaments, can deform the shape of membrane when confined in a membrane vesicle, playing an important role in biological processes. Here, we use dynamic Monte Carlo simulations to study an active polymer chain confined in a membrane vesicle. For flexible polymer chains, the membrane shape is governed by the competition between membrane bending rigidity and polymer activity. Stiff membrane is unaffected by small active forces, but moderate forces cause the polymer to alternate between stretched and disordered configurations, increasing the asphericity of both the polymer and the vesicle. For semi-flexible polymer chains, their stiffness can significantly impact both the vesicle and polymer shapes. We identify distinct classes of configurations that emerge as a function of polymer stiffness, membrane bending rigidity, and polymer activity. A weak polymer activity can cause the polymer to align along its contour, effectively increasing its stiffness. However, a moderate polymer activity softens the polymer chain. For membranes with low bending rigidities κ, large-scale deformations, such as wormlike or tadpole-shaped vesicles, appear at a weak polymer activity and high polymer stiffness. In the wormlike configuration, the polymer chain adopts a hairpin configuration to minimize the polymer bending energy. As the polymer stiffness increases, a tadpole-like vesicle forms, with part of the polymer deforming the membrane into a protrusion while the rest remaining confined in a bud-like structure. For stiffer membranes, we observe oblate vesicles containing toroidal polymer chains, resulting from the high cost of membrane bending energy. A moderate polymer activity causes the softening of the polymer chain, leading to a nearly spherical vesicle with slight shape fluctuation. We further characterize the order parameter of toroidal polymer chains in oblate vesicles and reveal that a slight increase in polymer activity leads to a more ordered helical structure of polymer chains.
Prognostic accuracy of the Stroke Rehabilitation Assessment of Movement (STREAM) scores on admission for walking independence in stroke patients at discharge and one-month follow-up
Gait prediction is critical in optimizing rehabilitation strategies for stroke survivors. This study evaluates the prognostic utility of the Stroke Rehabilitation Assessment of Movement (STREAM) scores, recorded at admission, for predicting walking ability at discharge and one-month follow-up. We assessed 47 stroke patients using STREAM at admission; walking independence was defined using two criteria: a Functional Ambulation Category (FAC) score > 3 and a 10-Meter Walk Test (10-MWT) speed ≥ 0.4 m/s. The predictive validity of STREAM scores was analyzed using the area under the receiver operating characteristic curve (AUC). Sensitivity, specificity, and cut-off values were computed. The analysis revealed that a STREAM score above 38 at admission significantly predicted independent gait by discharge, evidenced by a high AUC of 0.897. At the one-month follow-up, a cut-off score of 29 continued to predict walking independence, with an AUC of 0.987. The subscores further enhanced predictive accuracy and highlighted the effectiveness of the STREAM assessment as a robust predictor of independent walking in stroke patients. These findings suggest the practicality of using STREAM scores to predict walking independence, which can guide the planning of more effective rehabilitation interventions. Trial registration TCTR20240323004 at www.thaiclinicaltrials.org.
Exceptional ballisticity in monolayer BX (X = P, As, Sb) transistors
The initial excitement surrounding the potential use of two-dimensional (2D) semiconductors as a replacement for bulk silicon in ultra-thin body transistors has somewhat diminished due to their inferior room temperature mobility. Such phenomenon appears to be universal since it stems from the intrinsically high “density of scattering.” Here, we investigate three boron compounds, BP, BAs, and BSb, which show the potential to disrupt this universality due to their low effective masses and high optical phonon energies. Our investigation starts with the ab initio calculation of an inter- and an intravalley electron–phonon coupling matrix and the associated deformation potentials, which are then used to develop dissipative quantum transport models. We then calculate room temperature mobilities for electrons and holes using those models and find them superior to those of bulk silicon. We finally report the drain current characteristics of monolayer BX-based n- and p-type transistors, observing near-coherent transport and exceptional ballisticity (75%–87%) along with high drain current (1400–1900μAμm−1) in 25 nm channel length devices. Considering the various technological challenges associated with 2D transistor downscaling, BX may pave the way for realizing high-frequency integrated circuits based on 2D semiconductors.
Calculation of ion–ion mutual neutralization rate constants using Landau–Zener theory coupled with trajectory simulations for Ar<b>+</b>–Cl−, Br−, I−
In this computational study, we self-consistently calculate the rate constants of mutual neutralization reactions by incorporating the electron transfer probability, using Landau–Zener state transition theory with inputs derived from ab initio quantum chemistry calculations, into classical trajectory simulations. Electronic structure calculations are done using correlation consistent basis sets with multi-reference configuration interaction to map all the molecular electronic states below the ion-dissociation limit as a function of the distance between the reacting species. Our electronic structure calculations have been significantly improved from our previous work [Liu et al., J. Chem. Phys. 159, 114111 (2023)] through improved selection of molecular electronic configurations maintaining a fine grid of 1a0 over a wide range of bond lengths and accurate treatment of spin–orbit couplings. Non-adiabatic coupling matrix elements are calculated with the three-point central difference method near each avoided crossing to estimate the exact crossing point Rx and coupling parameter Hif, which are inputs to the multi-channel Landau–Zener theory to calculate the electron transition probability. Our approach is applied to estimate the mutual neutralization rate constants for the following ion pairs: Ar+–Cl−, Ar+–Br−, Ar+–I− at ∼133 Pa. Our predictions are compared against the experimental data reported by Shuman et al. [J. Chem. Phys. 140, 044304 (2014)]. It is seen that the improvement in the electronic structure calculation results in excellent agreement between the simulation results and the available experimental data to within a factor of ∼2 or ∼±50%.
Seasonal optical backscattering in hypersaline waters: In-situ observations and data analysis
Relationships of backscattering coefficients with the physical and biological properties in hypersaline waters like the Arabian Gulf are poorly studied. They may differ from other non-hypersaline waters which contribute the majority of data used to develop and parameterize optical models. Herein, we analyze the covariation of salinity, temperature, Chlorophyll-a (Chl-a), color dissolved organic matter (CDOM), ammonium, and turbidity with seawater backscattering coefficients bb(λ). This analysis is based on in-situ measurement of total backscattering and satellite total backscattering coefficients retrieved from the Visible Infrared Imaging Radiometer Suite (VIIRS). The in-situ measurements have been collected in the southern region of the Arabian Gulf waters, characterized by salinity and high evaporation rate. The results showed that turbidity is the main contributor to the increase in bb (λ) which could reach up to 77%. In addition, an increase in salinity is associated with an increase in the bb (λ) up to 19% especially at 532 nm. As for the temperature, we found that bb(λ) during the winter season is higher than in the summer season which could be due to the mixed effect of the surface sedimentation and the well-mixed column during winter. As for the Chl-a, there is a noticeable covariation between bb (λ) and the Chl-a concentration. Thus, we examined the probability distribution of Chl-a against different ranges of bb(λ) and found that Chl-a can follow log-normal and Weibull probability distribution which can be used for different bb(λ) ranges of 532 and 488 nm. Based on this study, we found that the hypersaline waters of the Gulf have bb scattering patterns that are consistent with the previously reported studies elsewhere.
Structural behaviors of lead zirconate titanate-based ferroelectric ceramics during pyroelectric-power generation cycles
Energy harvesting from waste heat can improve energy efficiency in society. This research investigated the structural behaviors of lead zirconate titanate–based ferroelectric ceramics using operando neutron diffraction measurements under the conditions of two energy-harvesting cycles that involve consideration of the temperature changes of automobile exhaust gas for achieving good harvesting efficiencies. Input and output electrical energies and neutron diffraction data were simultaneously collected. The obtained time-resolved neutron diffraction intensity data indicate that the applied electric fields and temperature changes induced 90° domain rotation and lattice strain. These structural changes and their variations depending on cycle conditions, such as temperature changes, applied electric fields, and circuit switching, provide insight into the origins of the differences in the behaviors of electrical input/output energies in the cycles.
Photoexcited dynamics of the valence states of norbornadiene
The non-radiative decay of photoexcited norbornadiene, which together with its isomer quadricyclane forms a molecular photoswitch, is investigated using surface-hopping non-adiabatic dynamics. The simulations are performed using four levels of electronic structure theory: CASSCF(2,2), CASSCF(4,4), XMS-CASPT2(2,2), and XMS-CASPT2(4,4). These electronic structure models yield two distinct classes of excited-state reaction pathways, with different quantum yields for the isomerization. This illustrates the significance of the potential energy surfaces when simulating photoexcited dynamics. The nature of the two reaction pathways is related to topographical features on the surfaces, suggesting potential “design rules” for chemical modification via substituent groups. How the molecule approaches the conical intersection is also shown to play a decisive role in the reaction outcome.
Hygroscopic effect of high clay-content shale under temperature and humidity conditions and its impact on mechanical properties
High clay-content shale, containing hydrophilic clay minerals, is highly sensitive to environmental temperature and humidity. It readily absorbs moisture from the air, leading to increased water content and reduced mechanical strength, which poses challenges for underground structures, such as mining roadways, tunnels, and storage chambers. This study investigates the influence of temperature and humidity on the water content of high clay-content shale during its hygroscopic process and examines the evolution of its mechanical properties under variations in water content, aiming to reveal the effects of environmental temperature and humidity on the mechanical behavior of high clay-content shale. Hygroscopic experiments were conducted using a temperature and humidity chamber, with quartz sand as non-clay mineral control groups, and strength experiments were performed on reconstituted shale samples with varying water content. Results from the hygroscopic experiments showed that the equilibrium water content (EWC) of high clay-content shale decreases with lower humidity and higher temperature. When the humidity decreased from 100% RH to 80% RH, the average EWC dropped from 15.88% to 7.53%. Under high-humidity conditions (100% RH), the EWC decreased to 11.92% only after the temperature increased to 30°C. Within the experimental conditions, reducing humidity was found to be more effective than increasing temperature in reducing EWC. Based on the mechanical test results, reducing humidity can decrease the loss of uniaxial compressive strength (UCS) caused by moisture absorption from approximately 50% to 15.48%. The results indicate that humidity is the primary factor influencing the EWC and mechanical properties of high clay-content shale. Reducing humidity can significantly mitigate strength loss caused by moisture absorption, while increasing temperature plays a supplementary role. These findings provide a scientific basis for controlling temperature and humidity in underground engineering to enhance structural stability.
Theoretical insights into the thermoelectric performance of 2D MXene Ti3C2
A class of two-dimensional (2D) materials known as MXenes has a layered structure and is expected to exhibit unique thermoelectric (TE) properties. Despite the high expectations for certain MXenes’ TE capabilities, there has been surprisingly limited theoretical research into this area. Inspired by the recent successful growth of 2D monolayer Ti3C2 MXene, here we explore the potential of pristine monolayer Ti3C2 as a TE material by means of first-principles density functional theory calculations in conjunction with a semi-classical Boltzmann transport approach. Furthermore, we investigate several crucial thermal and electrical transport parameters within the constant relaxation time approximation, including electron thermal and electrical conductivities. In addition, we calculate the Seebeck coefficients, power factor, and figure of merit in the Ti3C2 MXene monolayer and provide a conclusion of their suitability as a TE material. The electronic thermal conductivity, expressed in terms of the reduced chemical potential, increases with rising absolute temperature. In contrast, the electrical conductivity shows minimal changes with the temperatures under consideration. Our computational results set a reference for benchmarking and validation for experimentalists, enabling them to compare the TE performance of other semiconducting and functionalized MXenes.
Perspective: Time irreversibility in systems observed at coarse resolution
A broken time-reversal symmetry, i.e., broken detailed balance, is central to non-equilibrium physics and is a prerequisite for life. However, it turns out to be quite challenging to unambiguously define and quantify time-reversal symmetry (and violations thereof) in practice, that is, from observations. Measurements on complex systems have a finite resolution and generally probe low-dimensional projections of the underlying dynamics, which are well known to introduce memory. In situations where many microscopic states become “lumped” onto the same observable “state” or when introducing “reaction coordinates” to reduce the dimensionality of data, signatures of a broken time-reversal symmetry in the microscopic dynamics become distorted or masked. In this Perspective, we highlight why, in defining and discussing time-reversal symmetry and quantifying its violations, the precise underlying assumptions on the microscopic dynamics, the coarse graining, and further reductions are not a technical detail. These assumptions decide whether the conclusions that are drawn are physically sound or inconsistent. We summarize recent findings in the field and reflect upon key challenges.
Enhanced electromechanical performance of Si-modified lead-free BiFeO3-BaTiO3 ceramics for high-temperature piezoelectric applications
Environmental pollution generated by industrial wastes are deteriorating land, water, and marine life, which raises major concerns about climate change. Since environmentally friendly piezoelectric materials can generate clean energy by applying mechanical forces, they are seen as viable agents for industrial applications. In recent research work, the Si-modified 0.70Bi1.03FeO3-0.30BaTiO3 (BF30BT) environmentally friendly piezoceramics were synthesized using a solid-state method followed by a thermal quenching process. The crystalline structure, microstructure, and electromechanical characteristics were explored as a function of Si for both dopants (BC; before calcination) and additives (AC; after calcination). The result of pure BF30BT ceramic reveals a dominant rhombohedral phase exhibiting a d33 of 251 pC/N with a higher TC of 560 °C. The Si-doping gradually transformed the predominant rhombohedral phase to the rhombohedral-tetragonal mixed phase asymmetry as a result a good balance was achieved among d33 (209 pC/N), Qm (32.6), and kp (0.32%) with a high TC (465 °C). A giant-induced electric field bipolar strain of 0.39% corresponding to a large-signal piezoelectric coefficient d33* ≈ 750 pm/V was perceived in Si-doped BF30BT ceramic. The defect dipoles by acceptor doping play an essential role in the enhancement of piezoelectricity. The defect dipole aligns in the spontaneous polarization and also offers restoring force for domain switching leading to high asymmetric electrostrain. This study provides a good design benchmark for a new generation of eco-friendly large-strain actuator piezoceramics.
Temperature-driven flows in nanochannels: Theory and simulations
The motion of a fluid induced by thermal gradients in the absence of external forces is known as thermo-osmosis. The physical explanation of this phenomenon stems from the emergence of gradients in the tangential pressure due to the presence of a confining surface. The microscopic origin of the effect has recently been elucidated in the framework of linear response theory. Here, by use of conservation laws, we provide an explicit solution of the equations governing the fluid flow at stationarity in slab geometry, expressing the thermo-osmotic coefficient as the integrated mass current–heat current correlation function (which vanishes in the bulk). A very simple expression for the pressure gradient in terms of equilibrium properties is also derived. To test the theoretical predictions in a controlled setting, we performed extensive nonequilibrium molecular dynamics simulations in two dimensions. Few simple models of wall–particle interactions are examined, and the resulting pressure drop and velocity profile are compared with the theoretical predictions both in the liquid regime and in the gas regime.
A hemoperfusion column selectively adsorbs LAP+ lymphocytes to improve anti-tumor immunity and survival of tumor-bearing rats
Reducing the number of immunosuppressive cells in blood is a potential strategy for activating anti-tumor immunity, which provides a promising approach to cancer treatment. In this study, we developed an adsorbent designed to selectively target and adsorb lymphocytes expressing latency-associated peptide (LAP), which is abundantly expressed on the surface of CD4 + regulatory T cells (Tregs) and CD14 + monocytes. We investigated whether diethylenetriamine-conjugated polysulfone adsorbent-based direct hemoperfusion (DHP) enhances anti-tumor immunity in a rat cancer model with KDH-V liver cells. Our findings revealed that DHP significantly reduced LAP + Tregs in both peripheral blood and tumor tissues in treated mice. Consequently, cytotoxic T-lymphocytes increased in tumor-bearing rats. The anti-tumor effect was negated by the addition of cells detached from the absorbent, indicating that these cells play a crucial role in inhibiting the observed therapeutic effect. The results suggest that depleting LAP + immunosuppressive cells in blood can enhance anti-tumor immunity and improve survival of patients.
Hypnotic drug use and intraoperative fluid balance associated with postoperative delirium following pancreatic surgery: A retrospective, observational, single-center study
Background Postoperative delirium is a common complication after various types of major surgery. The aim of this study was to identify risk factors associated with delirium following pancreatic surgery. Methods Data from the patients who had pancreatic surgery between July 2020 and March 2021 in Ruijin Hospital affiliated with Shanghai Jiao Tong University School of Medicine were retrospectively analysed. The postoperative risk factors related to delirium were analyzed by univariate and multivariate Logistic regression analysis. Results 59 of 385 patients (15.3%) developed postoperative delirium after pancreatic surgery. The ROC curve revealed the optimal cutoff of intraoperative fluid balance was 2863ml. Furthermore, the multivariate analysis demonstrated that age ≥ 65 years old [Odds ratio (OR) 2.01; 95% Confidence interval (CI) 1.12-3.63; p = 0.019], hypnotic drug use (OR 4.17; 95% CI 1.50-11.10; p = 0.005), and intraoperative fluid balance (OR 2.57; 95% CI 1.37-4.84; p = 0.003) were the independent risk factors of postoperative delirium. Conclusion This study identified that intraoperative fluid balance and hypnotic drug use were independent risk factors associated with postoperative delirium development after pancreatic surgery.
The burden of unlawful use of opioid and associated epidemiological characteristics in Africa: A scoping review
Introduction There is an ongoing global upsurge of opioid misuse, fatal overdose and other related disorders, significantly affecting the African continent, due to resource-limited settings and poor epidemiological surveillance systems. This scoping review maps scientific evidence on epidemiological data on unlawful opioid use to identify knowledge gaps and policy shortcomings. Method The databases (PubMed, Scopus, Web of Sciences) and references were searched guided by Population, Concept, and Context (PCC) and PRISMA-ScR. The extracted characteristics examined were author/year, African country, epidemiological distribution, age group (year), gender, study design and setting, common opioid/s abused, sources of drugs, reasons for misuse, summary outcomes and future engagement. Results A population of 55132 participated in the included studies of 68 articles, with the largest sample size of 17260 (31.31%) in a study done in South Africa, 11281(20.46%) in a study from Egypt and 4068 (7.38%) in a study from Ethiopia. The gender of the participants was indicated in 65(95.59%) papers. The mean and median age reported in 57(83.82%) papers were 15.9-38, and 22-31years. The majority of study-designs were cross-sectional, 44(64.71%), and the most used opioids were heroin, 14articles (20.59%), tramadol, 8articles (11.76%), and tramadol & heroin, 6 articles (8.82%) articles. Study-settings included urban community 15(22.06%), hospital 15(22.06%), university students 11(16.18%), and secondary school learners 6(8.82%). The highest epidemiological distributions were recorded in the South African study, 19615(35.60%), Egyptian study, 14627(26.54%), and Nigerian study 5895(10.70%). Nine (13.24%) papers reported major opioid sources as black market, friends, and drug dealers. To relieve stress, physical pain and premature ejaculation, improve mood and sleep-related problems and help to continue work, were the major reasons for taking these drugs as reported in twenty articles (29.41%). Conclusion The findings of this scoping review show significant knowledge gaps on opioid usage in the African continent. The epidemiological distribution of unlawful use of opioids among young adults, drivers, and manual labourers in both genders is evident in the findings. The reason for use necessity scrutinises the role of social interaction, friends and family influence on illicit opiate use. Therefore, there is a need for regular epidemiological surveillance and investigations into multilevel, value-based, comprehensive, and strategic long-term intervention plans to curb the opioid problem in the region.
Sequences within and upstream of the mouse Ets1 gene drive high level expression in B cells, but are not sufficient for consistent expression in T cells
The levels of transcription factor Ets1 are high in resting B and T cells, but are downregulated by signaling through antigen receptors and Toll-like receptors (TLRs). Loss of Ets1 in mice leads to excessive immune cell activation and development of an autoimmune syndrome and reduced Ets1 expression has been observed in human PBMCs in the context of autoimmune diseases. In B cells, Ets1 serves to prevent premature activation and differentiation to antibody-secreting cells. Given these important roles for Ets1 in the immune response, stringent control of Ets1 gene expression levels is required for homeostasis. However, the genetic regulatory elements that control expression of the Ets1 gene remain relatively unknown. Here we identify a topologically-associating domain (TAD) in the chromatin of B cells that includes the mouse Ets1 gene locus and describe an interaction hub that extends over 100 kb upstream and into the gene body. Additionally, we compile epigenetic datasets to find several putative regulatory elements within the interaction hub by identifying regions of high DNA accessibility and enrichment of active enhancer histone marks. Using reporter constructs, we determine that DNA sequences within this interaction hub are sufficient to direct reporter gene expression in lymphoid tissues of transgenic mice. Further analysis indicates that the reporter construct drives faithful expression of the reporter gene in mouse B cells, but variegated expression in T cells, suggesting the existence of T cell regulatory elements outside this region. To investigate how the downregulation of Ets1 transcription is associated with alterations in the epigenetic landscape of stimulated B cells, we performed ATAC-seq in resting and BCR-stimulated primary B cells and identified four regions within and upstream of the Ets1 locus that undergo changes in chromatin accessibility that correlate to Ets1 gene expression. Interestingly, functional analysis of several putative Ets1 regulatory elements using luciferase constructs suggested a high level of functional redundancy. Taken together our studies reveal a complex network of regulatory elements and transcription factors that coordinate the B cell-specific expression of Ets1 .