BU Open Access Articleshttps://hdl.handle.net/2144/168442022-05-20T03:03:58Z2022-05-20T03:03:58ZAttack of the clones: microglia in health and diseaseManjally, Amritha VinayakTay, Tuan Lenghttps://hdl.handle.net/2144/444042022-05-13T08:36:44Z2022-01-01T00:00:00ZAttack of the clones: microglia in health and disease
Manjally, Amritha Vinayak; Tay, Tuan Leng
[INTRODUCTION]
Microglia are brain-resident macrophages that carry out immune surveillance, support neurogenesis and neuronal survival, shape the neuronal network, and maintain tissue homeostasis (Nimmerjahn et al., 2005; Hanisch and Kettenmann, 2007; Sierra et al., 2010; Tremblay et al., 2010; Schafer et al., 2012; Ueno et al., 2013; Squarzoni et al., 2014; Schafer and Stevens, 2015; Diaz-Aparicio et al., 2020). The adult resident pool of microglia is primarily derived from yolk sac (YS) erythromyeloid progenitors (EMPs) that have clonally proliferated within the brain parenchyma during development (Alliot et al., 1999; Ginhoux et al., 2010; Hashimoto et al., 2013; Gomez Perdiguero et al., 2015). To maintain their cell density in adulthood, the resident microglial cells undergo local clonal self-renewal (Ajami et al., 2007; Askew et al., 2017; Réu et al., 2017; Tay et al., 2017). A study on parabiotic chimeric mice revealed that the resident microglial population is exclusively replenished by locally derived microglial clones with no evidence of contribution from peripheral myeloid progenitors (Ajami et al., 2007). Clonal expansion of non-ablated residual microglia was also found to be responsible for re-establishing steady state microglial cell densities following a pharmacological ablation (Huang et al., 2018). Homeostatic microglia continuously monitor the brain environment, scavenge dying cells and cellular debris, and rapidly respond to any tissue damage (Kreutzberg, 1996; Streit et al., 1999). In response to acute pathology, resident microglia rapidly accumulate around the lesion via clonal microgliosis (Streit et al., 1999; Ladeby et al., 2005; Ajami et al., 2007; Ransohoff, 2007). Microgliosis at the site of CNS damage has been shown to be governed by signaling molecules like colony-stimulating factor-1 (CSF1), fractalkine receptor (CX3CR1) and purinergic receptor P2Y12 (P2RY12) (Guan et al., 2016; Gu et al., 2016; Peng et al., 2016). To repair damage, microglia elicit proinflammatory cytokines and later transition to anti-inflammatory phenotypes (Colton, 2009; Lloyd et al., 2019). Several studies have suggested that clinical recovery of acute lesions is accompanied by the resolution of proliferated microglia by migration and cell death (Dihné et al., 2001; Wilson et al., 2004; Tay et al., 2017; Lloyd et al., 2019). However, in severe or chronic neurodegenerative pathologies like Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), and motor neuron diseases, microglial clonal expansion has been persistently observed around lesions and plaques (Glass et al., 2010; Streit et al., 2020). In AD and MS animal models, microglial proliferation around the Aβ plaques and demyelinating neurons was actively promoted by CSF1R and triggering receptor expressed on myeloid cells 2 (TREM2) (Cantoni et al., 2015; Olmos-Alonso et al., 2016; Wang et al., 2016; Jay et al., 2017; Gushchina et al., 2018; Zhao et al., 2018). CSF1R, transforming growth factor beta (TGFβ), and purinergic signaling pathways that influence microglial cell densities are impaired in neurodegenerative diseases (Gómez-Nicola et al., 2013; Von Bernhardi et al., 2015; Olmos-Alonso et al., 2016; Pietrowski et al., 2021). Taken together, the capacity for microglial clonal expansion, proliferation, or renewal, clearly play an important function across CNS development, health, and disease. Although clonal expansion and renewal of microglia appears necessary for physiological brain development, maintenance of CNS health, and response to acute damage, whether microglial clones are beneficial or detrimental in chronic neurodegeneration remains unclear.
In this opinion article, we discuss the implications of the formation of microglial clones in health and disease, independent of peripheral myeloid recruitment to the CNS in similar contexts (Figure 1). Several studies have claimed that microglia surrounding plaques and lesions exert detrimental effects and exacerbate disease conditions (Streit et al., 2009; Lassmann et al., 2012; Keren-Shaul et al., 2017; Krasemann et al., 2017; Shahidehpour et al., 2021). Considering that the restoration of tissue homeostasis coincides with the resolution of microglial clones to regain steady state microglial tiling (Dihné et al., 2001; Wilson et al., 2004; Tay et al., 2017; Lloyd et al., 2019), we hypothesize that unresolved microglial clones contribute to the prolongation of neurodegenerative states in chronic neuropathologies. As a hallmark of CNS pathology, microgliosis is likely important to limit tissue damage and infection and for local repair, as is typical in inflammatory responses of tissue-resident macrophages (Jenkins et al., 2011). A timely resolution of excess microglia resulting from clonal expansion is expected to aid or accompany the restoration of homeostasis and clinical recovery. However, sustained presence of reactive microglial clones at high densities around lesions or plaques with no signs of resolution likely lead to neurotoxic outcomes. To explore our hypothesis, we examine various contexts in which microglial clonal expansion has taken place and consider if strategic targeting of microglial clones could ameliorate chronic disease states.
2022-01-01T00:00:00ZInformative predictors of pregnancy after first IVF cycle using eIVF practice highway electronic health recordsXu, Tingtingde Figueiredo Veiga, AlexisHammer, Karissa C.Paschalidis, Ioannis C.Mahalingaiah, Shruthihttps://hdl.handle.net/2144/444032022-05-13T04:46:48Z2022-01-17T00:00:00ZInformative predictors of pregnancy after first IVF cycle using eIVF practice highway electronic health records
Xu, Tingting; de Figueiredo Veiga, Alexis; Hammer, Karissa C.; Paschalidis, Ioannis C.; Mahalingaiah, Shruthi
The aim of this study is to determine the most informative pre- and in-cycle variables for predicting success for a first autologous oocyte in-vitro fertilization (IVF) cycle. This is a retrospective study using 22,413 first autologous oocyte IVF cycles from 2001 to 2018. Models were developed to predict pregnancy following an IVF cycle with a fresh embryo transfer. The importance of each variable was determined by its coefficient in a logistic regression model and the prediction accuracy based on different variable sets was reported. The area under the receiver operating characteristic curve (AUC) on a validation patient cohort was the metric for prediction accuracy. Three factors were found to be of importance when predicting IVF success: age in three groups (38-40, 41-42, and above 42 years old), number of transferred embryos, and number of cryopreserved embryos. For predicting first-cycle IVF pregnancy using all available variables, the predictive model achieved an AUC of 68% + /- 0.01%. A parsimonious predictive model utilizing age (38-40, 41-42, and above 42 years old), number of transferred embryos, and number of cryopreserved embryos achieved an AUC of 65% + /- 0.01%. The proposed models accurately predict a single IVF cycle pregnancy outcome and identify important predictive variables associated with the outcome. These models are limited to predicting pregnancy immediately after the IVF cycle and not live birth. These models do not include indicators of multiple gestation and are not intended for clinical application.
2022-01-17T00:00:00ZQuantitative birefringence microscopy for imaging the structural integrity of CNS myelin following circumscribed cortical injury in the rhesus monkeyBlanke, NathanGo, VeronicaRosene, Douglas L.L.Bigio, Irving J.https://hdl.handle.net/2144/444022022-05-13T04:46:45Z2021-03-22T00:00:00ZQuantitative birefringence microscopy for imaging the structural integrity of CNS myelin following circumscribed cortical injury in the rhesus monkey
Blanke, Nathan; Go, Veronica; Rosene, Douglas L.L.; Bigio, Irving J.
Significance: Myelin breakdown is likely a key factor in the loss of cognitive and motor function associated with many neurodegenerative diseases.
Aim: New methods for imaging myelin structure are needed to characterize and quantify the degradation of myelin in standard whole-brain sections of nonhuman primates and in human brain.
Approach: Quantitative birefringence microscopy (qBRM) is a label-free technique for rapid histopathological assessment of myelin structural breakdown following cortical injury in rhesus monkeys.
Results: We validate birefringence microscopy for structural imaging of myelin in rhesus monkey brain sections, and we demonstrate the power of qBRM by characterizing the breakdown of myelin following cortical injury, as a model of stroke, in the motor cortex.
Conclusions: Birefringence microscopy is a valuable tool for histopathology of myelin and for quantitative assessment of myelin structure. Compared to conventional methods, this label-free technique is sensitive to subtle changes in myelin structure, is fast, and enables more quantitative assessment, without the variability inherent in labeling procedures such as immunohistochemistry.
2021-03-22T00:00:00ZThe impact of payer status on hospital admissions: evidence from an academic medical centerZhao, YanyingPaschalidis, Ioannis C.Hu, Jianqianghttps://hdl.handle.net/2144/444012022-05-13T04:46:44Z2021-09-07T00:00:00ZThe impact of payer status on hospital admissions: evidence from an academic medical center
Zhao, Yanying; Paschalidis, Ioannis C.; Hu, Jianqiang
BACKGROUND: There are plenty of studies investigating the disparity of payer status in accessing to care. However, most studies are either disease-specific or cohort-specific. Quantifying the disparity from the level of facility through a large controlled study are rare. This study aims to examine how the payer status affects patient hospitalization from the perspective of a facility. METHODS: We extracted all patients with visiting record in a medical center between 5/1/2009-4/30/2014, and then linked the outpatient and inpatient records three year before target admission time to patients. We conduct a retrospective observational study using a conditional logistic regression methodology. To control the illness of patients with different diseases in training the model, we construct a three-dimension variable with data stratification technology. The model is validated on a dataset distinct from the one used for training. RESULTS: Patients covered by private insurance or uninsured are less likely to be hospitalized than patients insured by government. For uninsured patients, inequity in access to hospitalization is observed. The value of standardized coefficients indicates that government-sponsored insurance has the greatest impact on improving patients' hospitalization. CONCLUSION: Attention is needed on improving the access to care for uninsured patients. Also, basic preventive care services should be enhanced, especially for people insured by government. The findings can serve as a baseline from which to measure the anticipated effect of measures to reduce disparity of payer status in hospitalization.
2021-09-07T00:00:00ZTemperature dependence of the (π,0) anomaly in the excitation spectrum of the 2D quantum Heisenberg antiferromagnetWan, W.Christensen, N.B.Sandvik, Anders W.Tregenna-Piggott, P.Nilsen, G.J.Mourigal, M.Perring, T.G.Frost, C.D.McMorrow, D.F.Rønnow, H.M.https://hdl.handle.net/2144/444002022-05-13T04:46:43Z2019-01-01T00:00:00ZTemperature dependence of the (π,0) anomaly in the excitation spectrum of the 2D quantum Heisenberg antiferromagnet
Wan, W.; Christensen, N.B.; Sandvik, Anders W.; Tregenna-Piggott, P.; Nilsen, G.J.; Mourigal, M.; Perring, T.G.; Frost, C.D.; McMorrow, D.F.; Rønnow, H.M.
It is well established that in the low-temperature limit, the two-dimensional quantum Heisenberg antiferromagnet on a square lattice (2DQHAFSL) exhibits an anomaly in its spectrum at short-wavelengths on the zone-boundary. In the vicinity of the (π,0) point the pole in the one-magnon response exhibits a downward dispersion, is heavily damped and attenuated, giving way to an isotropic continuum of excitations extending to high energies. The origin of the anomaly and the presence of the continuum are of current theoretical interest, with suggestions focused around the idea that the latter evidences the existence of spinons in a two-dimensional system. Here we present the results of neutron inelastic scattering experiments and Quantum Monte Carlo calculations on the metallo-organic compound Cu(DCOO)2⋅4D2O (CFTD), an excellent physical realisation of the 2DQHAFSL, designed to investigate how the anomaly at (π,0) evolves up to finite temperatures T/J∼2/3. Our data reveal that on warming the anomaly survives the loss of long-range, three-dimensional order, and is thus a robust feature of the two-dimensional system. With further increase of temperature the zone-boundary response gradually softens and broadens, washing out the (π,0) anomaly. This is confirmed by a comparison of our data with the results of finite-temperature Quantum Monte Carlo simulations where the two are found to be in good accord. At lower energies, in the vicinity of the antiferromagnetic zone centre, there was no significant softening of the magnetic excitations over the range of temperatures investigated.
Dedicated to the life and work of Professor Roger Cowley. 22 pages, 8 figures
2019-01-01T00:00:00ZFractional and composite excitations of antiferromagnetic quantum spin trimer chainsCheng, Jun-QingLi, JunXiong, ZijianWu, Han-QingSandvik, Anders W.Yao, Dao-Xinhttps://hdl.handle.net/2144/443992022-05-13T08:51:36Z2022-12-01T00:00:00ZFractional and composite excitations of antiferromagnetic quantum spin trimer chains
Cheng, Jun-Qing; Li, Jun; Xiong, Zijian; Wu, Han-Qing; Sandvik, Anders W.; Yao, Dao-Xin
Using quantum Monte Carlo, exact diagonalization, and perturbation theory, we study the spectrum of the S = 1/2 antiferromagnetic Heisenberg trimer chain by varying the ratio g = J2/J1 of the intertrimer and intratrimer coupling strengths. The doublet ground states of trimers form effective interacting S = 1/2 degrees of freedom described by a Heisenberg chain. Therefore, the conventional two-spinon continuum of width ∝ J1 when g = 1 evolves into to a similar continuum of width ∝ J2 when g → 0. The intermediate-energy and high-energy modes are termed doublons and quartons which fractionalize with increasing g to form the conventional spinon continuum. In particular, at g ≈ 0.716, the gap between the low-energy spinon branch and the high-energy band with mixed doublons, quartons, and spinons closes. These features should be observable in inelastic neutron scattering experiments if a quasi-one-dimensional quantum magnet with the linear trimer structure and J2 < J1 can be identified. Our results may open a window for exploring the high-energy fractional excitations.
2022-12-01T00:00:00ZHow Rolling Stones drummer Charlie Watts infused one of the greatest rock 'n' roll bands with a little jazzCoelho, Victorhttps://hdl.handle.net/2144/443982022-05-13T08:52:09Z2021-08-24T00:00:00ZHow Rolling Stones drummer Charlie Watts infused one of the greatest rock 'n' roll bands with a little jazz
Coelho, Victor
2021-08-24T00:00:00ZGlass-fiber-reinforced polymeric film as an efficient protecting layer for stable Li metal electrodesGao, ShilunCannon, AndrewSun, FeiyuanPan, YiyangYang, DandanGe, SiruiLiu, NianSokolov, Alexei P.Ryan, EmilyYang, HuabinCao, Peng-Feihttps://hdl.handle.net/2144/443972022-05-12T04:54:30Z2021-08-01T00:00:00ZGlass-fiber-reinforced polymeric film as an efficient protecting layer for stable Li metal electrodes
Gao, Shilun; Cannon, Andrew; Sun, Feiyuan; Pan, Yiyang; Yang, Dandan; Ge, Sirui; Liu, Nian; Sokolov, Alexei P.; Ryan, Emily; Yang, Huabin; Cao, Peng-Fei
[SUMMARY] With numerous reports on protecting films for stable lithium (Li) metal electrodes, the key attributes for how to construct these efficient layers have rarely been fully investigated. Here, we report a rationally designed hybrid protective layer (HPL) with each component aligning with one key attribute; i.e., cross-linked poly(dimethylsiloxane) (PDMS) enhances flexibility, polyethylene glycol (PEG) provides homogeneous ion-conducting channels, and glass fiber (GF) affords mechanical robustness. A significant improvement of the electrochemical performance of HPL-modified electrodes can be achieved in Li/HPL@Cu half cells, HPL@Li/HPL@Li symmetric cells, and HPL@Li/LiFePO4 full cells. Even with an industrial standard LiFePO4 cathode (96.8 wt % active material), the assembled cell still exhibits a capacity retention of 90% after 100 cycles at 1 C. More importantly, the functionality of each component has been studied comprehensively via electrochemical and physical experiments and simulations, which will provide useful guidance on how to construct efficient protective layers for next-generation energy storage devices.
2021-08-01T00:00:00ZKnowing your design history is crucial to aesthetic innovationCoogan, Kristenhttps://hdl.handle.net/2144/443962022-05-12T04:54:28Z2020-06-22T00:00:00ZKnowing your design history is crucial to aesthetic innovation
Coogan, Kristen
Style cycles in and out of fashion—history helps us decode the present and forecast the future
2020-06-22T00:00:00ZThe most irrational rational theoriesBenjamin, NathanDyer, EthanFitzpatrick, A. LiamXin, Yuanhttps://hdl.handle.net/2144/443952022-05-12T08:56:43Z2019-04-01T00:00:00ZThe most irrational rational theories
Benjamin, Nathan; Dyer, Ethan; Fitzpatrick, A. Liam; Xin, Yuan
We propose a two-parameter family of modular invariant partition functions of two-dimensional conformal field theories (CFTs) holographically dual to pure three-dimensional gravity in anti de Sitter space. Our two parameters control the central charge, and the representation of SL(2, ℤ). At large central charge, the partition function has a gap to the first nontrivial primary state of 𝑐24. As the SL(2, ℤ) representation dimension gets large, the partition function exhibits some of the qualitative features of an irrational CFT. This, for instance, is captured in the behavior of the spectral form factor. As part of these analyses, we find similar behavior in the minimal model spectral form factor as c approaches 1.
2019-04-01T00:00:00ZThe bulk-to-boundary propagator in black hole microstate backgroundsChen, HongbinFitzpatrick, A. LiamKaplan, JaredLi, Dalianghttps://hdl.handle.net/2144/443942022-05-12T09:01:58Z2019-06-01T00:00:00ZThe bulk-to-boundary propagator in black hole microstate backgrounds
Chen, Hongbin; Fitzpatrick, A. Liam; Kaplan, Jared; Li, Daliang
First-quantized propagation in quantum gravitational AdS3 backgrounds can be exactly reconstructed using CFT2 data and Virasoro symmetry. We develop methods to compute the bulk-to-boundary propagator in a black hole microstate, ⟨𝜙𝐿𝒪𝐿𝒪𝐻𝒪𝐻⟩, at finite central charge. As a first application, we show that the semiclassical theory on the Euclidean BTZ solution sharply disagrees with the exact description, as expected based on the resolution of forbidden thermal singularities, though this effect may appear exponentially small for physical observers.
2019-06-01T00:00:00ZUniversal lowest-twist in CFTs from holographyFitzpatrick, A. LiamHuang, Kuo-Weihttps://hdl.handle.net/2144/443932022-05-12T09:06:55Z2019-08-01T00:00:00ZUniversal lowest-twist in CFTs from holography
Fitzpatrick, A. Liam; Huang, Kuo-Wei
We probe the conformal block structure of a scalar four-point function in d ≥ 2
conformal field theories by including higher-order derivative terms in a bulk gravitational
action. We consider a heavy-light four-point function as the boundary correlator at large
central charge. Such a four-point function can be computed, on the gravity side, as a
two-point function of the light operator in a black hole geometry created by the heavy
operator. We consider analytically solving the corresponding scalar field equation in a nearboundary expansion and find that the multi-stress tensor conformal blocks are insensitive
to the horizon boundary condition. The main result of this paper is that the lowest-twist
operator product expansion (OPE) coefficients of the multi-stress tensor conformal blocks
are universal: they are fixed by the dimension of the light operators and the ratio between
the dimension of the heavy operator and the central charge CT . Neither supersymmetry
nor unitary is assumed. Higher-twist coefficients, on the other hand, generally are not
protected. A recursion relation allows us to efficiently compute universal lowest-twist
coefficients. The universality result hints at the potential existence of a higher-dimensional
Virasoro-like symmetry near the lightcone. While we largely focus on the planar black hole
limit in this paper, we include some preliminary analysis of the spherical black hole case
in an appendix.
2019-08-01T00:00:00ZProbing universalities in d > 2 CFTs: from black holes to shockwavesFitzpatrick, A. LiamHuang, Kuo-WeiLi, Dalianghttps://hdl.handle.net/2144/443922022-05-12T09:09:21Z2019-11-01T00:00:00ZProbing universalities in d > 2 CFTs: from black holes to shockwaves
Fitzpatrick, A. Liam; Huang, Kuo-Wei; Li, Daliang
Gravitational shockwaves are insensitive to higher-curvature corrections in the action. Recent work found that the OPE coefficients of lowest-twist multi-stress-tensor operators, computed holographically in a planar black hole background, are insensitive as well. In this paper, we analyze the relation between these two limits. We explicitly evaluate the two-point function on a shockwave background to all orders in a large central charge expansion. In the geodesic limit, we find that the ANEC exponentiates in the multi-stress-tensor sector. To compare with the black hole limit, we obtain a recursion relation for the lowest-twist products of two stress tensors in a spherical black hole background, letting us efficiently compute their OPE coefficients and prove their insensitivity to higher curvature terms. After resumming the lowest-twist stress-tensors and analytically continuing their contributions to the Regge limit, we find a perfect agreement with the shockwave computation. We also discuss the role of double-trace operators, global degenerate states, and multi-stress-tensor conformal blocks. These holographic results suggest the existence of a larger universal structure in higher-dimensional CFTs.
2019-11-01T00:00:00ZIntroduction to lightcone conformal truncation: QFT dynamics from CFT dataAnand, NikhilFitzpatrick, A. LiamKatz, EmanuelKhandker, Zuhair U.Walters, Matthew T.Xin, Yuanhttps://hdl.handle.net/2144/443912022-05-12T04:54:22Z2020-05-27T00:00:00ZIntroduction to lightcone conformal truncation: QFT dynamics from CFT data
Anand, Nikhil; Fitzpatrick, A. Liam; Katz, Emanuel; Khandker, Zuhair U.; Walters, Matthew T.; Xin, Yuan
We both review and augment the lightcone conformal truncation (LCT) method. LCT is a Hamiltonian truncation method for calculating dynamical quantities in QFT in infinite volume. This document is a self-contained, pedagogical introduction and "how-to" manual for LCT. We focus on 2D QFTs which have UV descriptions as free CFTs containing scalars, fermions, and gauge fields, providing a rich starting arena for LCT applications. Along our way, we develop several new techniques and innovations that greatly enhance the efficiency and applicability of LCT. These include the development of CFT radial quantization methods for computing Hamiltonian matrix elements and a new SUSY-inspired way of avoiding state-dependent counterterms and maintaining chiral symmetry. We walk readers through the construction of their own basic LCT code, sufficient for small truncation cutoffs. We also provide a more sophisticated and comprehensive set of Mathematica packages and demonstrations that can be used to study a variety of 2D models. We guide the reader through these packages with several examples and illustrate how to obtain QFT observables, such as spectral densities and the Zamolodchikov $C$-function. Specific models considered are finite $N_c$ QCD, scalar $\phi^4$ theory, and Yukawa theory.
2020-05-27T00:00:00ZNonperturbative matching between equal-time and lightcone quantizationFitzpatrick, A. LiamKatz, EmanuelWalters, Matthew T.https://hdl.handle.net/2144/443902022-05-12T09:11:50Z2020-10-01T00:00:00ZNonperturbative matching between equal-time and lightcone quantization
Fitzpatrick, A. Liam; Katz, Emanuel; Walters, Matthew T.
We investigate the nonperturbative relation between lightcone (LC) and standard equal-time (ET) quantization in the context of λϕ4 theory in d = 2. We discuss the perturbative matching between bare parameters and the failure of its naive nonperturbative extension. We argue that they are nevertheless the same theory nonperturbatively, and that furthermore the nonperturbative map between bare parameters can be extracted from ET perturbation theory via Borel resummation of the mass gap. We test this map by using it to compare physical quantities computed using numerical Hamiltonian truncation methods in ET and LC.
2020-10-01T00:00:00ZModel-dependence of minimal-twist OPEs in d > 2 holographic CFTsFitzpatrick, A. LiamHuang, Kuo-WeiMeltzer, DavidPerlmutter, EricSimmons-Duffin, Davidhttps://hdl.handle.net/2144/443892022-05-12T09:13:45Z2020-11-01T00:00:00ZModel-dependence of minimal-twist OPEs in d > 2 holographic CFTs
Fitzpatrick, A. Liam; Huang, Kuo-Wei; Meltzer, David; Perlmutter, Eric; Simmons-Duffin, David
Following recent work on heavy-light correlators in higher-dimensional conformal field theories (CFTs) with a large central charge CT, we clarify the properties of stress tensor composite primary operators of minimal twist, [Tm], using arguments in both CFT and gravity. We provide an efficient proof that the three-point coupling ⟨𝒪𝐿𝒪𝐿[𝑇𝑚]⟩, where 𝒪𝐿 is any light primary operator, is independent of the purely gravitational action. Next, we consider corrections to this coupling due to additional interactions in AdS effective field theory and the corresponding dual CFT. When the CFT contains a non-zero three-point coupling ⟨𝑇𝑇𝒪𝐿⟩, the three-point coupling ⟨𝒪𝐿𝒪𝐿[𝑇2]⟩ is modified at large CT if ⟨𝑇𝑇𝒪𝐿⟩∼𝐶𝑇‾‾‾√. This scaling is obeyed by the dilaton, by Kaluza-Klein modes of prototypical supergravity compactifications, and by scalars in stress tensor multiplets of supersymmetric CFTs. Quartic derivative interactions involving the graviton and the light probe field dual to 𝒪𝐿 can also modify the minimal-twist couplings; these local interactions may be generated by integrating out a spin-ℓ ≥ 2 bulk field at tree level, or any spin ℓ at loop level. These results show how the minimal-twist OPE coefficients can depend on the higher-spin gap scale, even perturbatively.
2020-11-01T00:00:00ZSolving the 2D SUSY Gross-Neveu-Yukawa Model with Conformal TruncationFitzpatrick, A. LiamKatz, EmanuelWalters, Matthew T.Xin, Yuanhttps://hdl.handle.net/2144/443882022-05-12T09:16:12Z2021-01-27T00:00:00ZSolving the 2D SUSY Gross-Neveu-Yukawa Model with Conformal Truncation
Fitzpatrick, A. Liam; Katz, Emanuel; Walters, Matthew T.; Xin, Yuan
We use Lightcone Conformal Truncation to analyze the RG flow of the two-dimensional supersymmetric Gross-Neveu-Yukawa theory, i.e. the theory of a real scalar superfield with a $\mathbb{Z}_2$-symmetric cubic superpotential. The theory depends on a single dimensionless coupling $\bar{g}$, and is expected to have a critical point at a tuned value $\bar{g}_*$ where it flows in the IR to the Tricritical Ising Model (TIM); the theory spontaneously breaks the $\mathbb{Z}_2$ symmetry on one side of this phase transition, and breaks SUSY on the other side. We calculate the spectrum of energies as a function of $\bar{g}$ and see the gap close as the critical point is approached, and numerically read off the critical exponent $\nu$ in TIM. Beyond the critical point, the gap remains nearly zero, in agreement with the expectation of a massless Goldstino. We also study spectral functions of local operators on both sides of the phase transition and compare to analytic predictions where possible. In particular, we use the Zamolodchikov $C$-function to map the entire phase diagram of the theory. Crucial to this analysis is the fact that our truncation is able to preserve supersymmetry sufficiently to avoid any additional fine tuning.
2021-01-27T00:00:00ZLattice setup for quantum field theory in AdS2Brower, Richard C.Cogburn, Cameron V.Fitzpatrick, A. LiamHowarth, DeanTan, Chung-Ihttps://hdl.handle.net/2144/443872022-05-12T09:17:13Z2021-01-01T00:00:00ZLattice setup for quantum field theory in AdS2
Brower, Richard C.; Cogburn, Cameron V.; Fitzpatrick, A. Liam; Howarth, Dean; Tan, Chung-I
Holographic conformal field theories (CFTs) are usually studied in a limit where the gravity description is weakly coupled. By contrast, lattice quantum field theory can be used as a tool for doing computations in a wider class of holographic CFTs where nongravitational interactions in AdS become strong, and gravity is decoupled. We take preliminary steps for studying such theories on the lattice by constructing the discretized theory of a scalar field in
AdS
2
and investigating its approach to the continuum limit in the free and perturbative regimes. Our main focus is on finite sublattices of maximally symmetric tilings of hyperbolic space. Up to boundary effects, these tilings preserve the triangle group as a large discrete subgroup of
AdS
2
, but have a minimum lattice spacing that is comparable to the radius of curvature of the underlying spacetime. We quantify the effects of the lattice spacing as well as the boundary effects, and find that they can be accurately modeled by modifications within the framework of the continuum limit description. We also show how to do refinements of the lattice that shrink the lattice spacing at the cost of breaking the triangle group symmetry of the maximally symmetric tilings.
2021-01-01T00:00:00ZWomen and Global South strikingly underrepresented among top‐publishing ecologistsMaas, BeaPakeman, Robin J.Godet, LaurentSmith, LinneaDevictor, VincentPrimack, Richardhttps://hdl.handle.net/2144/443622022-05-06T04:32:06Z2021-07-01T00:00:00ZWomen and Global South strikingly underrepresented among top‐publishing ecologists
Maas, Bea; Pakeman, Robin J.; Godet, Laurent; Smith, Linnea; Devictor, Vincent; Primack, Richard
The global scientific community has become increasingly diverse over recent decades, but is this ongoing development also reflected among top-publishing authors and potential scientific leaders? We surveyed 13 leading journals in ecology, evolution, and conservation to investigate the diversity of the 100 top-publishing authors in each journal between 1945 and 2019. Out of 1051 individual top-publishing authors, only 11% are women. The United States, the United Kingdom, Australia, Germany, and Canada account for more than 75% of top-publishing authors, while countries of the Global South (as well as Russia, Japan, and South Korea) were strikingly underrepresented. The number of top-publishing authors who are women and/or are from the Global South is increasing only slowly over time. We outline transformative actions that scientific communities can take to enhance diversity, equity and inclusion at author, leadership, and society level. The resulting promotion of scientific innovation and productivity is essential for the development of global solutions in conservation science.
2021-07-01T00:00:00ZBiodiversity science blossoms in ChinaPrimack, Richard B.https://hdl.handle.net/2144/443612022-05-06T04:32:05Z2021-07-01T00:00:00ZBiodiversity science blossoms in China
Primack, Richard B.
[Over the past 35 years, China has been transformed by an economic miracle unlike anything seen in the history of the world. Hundreds of millions of people have emerged from rural poverty, cities have been re-built, cutting-edge industries have been established and a modern transportation network now knits together the country. This transformation has come at a significant cost to the environment, in terms of air pollution, water pollution, the loss and fragmentation of habitats, and threats of species extinction. Yet, as the review by Mi et al. (2021) points out, China is also now emerging as a leader in biodiversity conservation and research [1]. This focus on finding a balance between biodiversity conservation and socio-economic development, sometimes referred to as ‘ecological civilization,’ is a high priority in China because of the dependence of its enormous human population on ecosystem services and because of its astonishing richness of species.]
2021-07-01T00:00:00Z