Shot Noise Suppression in Avalanche Photodiodes

We identify a new shot noise suppression mechanism in a thin (~100 nm) heterostructure avalanche photodiode. In the low-gain regime the shot noise is suppressed due to temporal correlations within amplified current pulses. We demonstrate in a Monte Carlo simulation that the effective excess noise factors can be <1, and reconcile the apparent conflict between theory and experiments. This shot noise suppression mechanism is independent of known mechanisms such as Coulomb interaction, or reflection at heterojunction interfaces.Comment: Phys. Rev. Lett., accepted for publicatio

Disruption of the mouse MRF4 gene identifies multiple waves of myogenesis in the myotome

MRF4 (herculin/Myf-6) is one of the four member MyoD family of transcription factors identified by their ability to enforce skeletal muscle differentiation upon a wide variety of nonmuscle cell types. In this study the mouse germline MRF4 gene was disrupted by targeted recombination. Animals homozygous for the MRF4bh1 allele, a deletion of the functionally essential bHLH domain, displayed defective axial myogenesis and rib pattern formation, and they died at birth. Differences in somitogenesis between homozygous MRF4bh1 embryos and their wild-type littermates provided evidence for three distinct myogenic regulatory programs (My1-My3) in the somite, which correlate temporally and spatially with three waves of cellular recruitment to the expanding myotome. The first program (My1), marked initially by Myf-5 expression and followed by myogenin, began on schedule in the MRF4bh1/bh1 embryos at day 8 post coitum (E8). A second program (My2) was highly deficient in homozygous mutant MRF4 embryos, and normal expansion of the myotome failed. Moreover, expression of downstream muscle-specific genes, including FGF-6, which is a candidate regulator of inductive interactions, did not occur normally. The onset of MyoD expression around E10.5 in wild-type embryos marks a third myotomal program (My3), the execution of which was somewhat delayed in MRF4 mutant embryos but ultimately led to extensive myogenesis in the trunk. By E15 it appeared to have largely compensated for the defective My2 program in MRF4 mutants. Homozygous MRF4bh1 animals also showed improper rib pattern formation perhaps due to the absence of signals from cells expressing the My2 program. Finally, a later and relatively mild phenotype was detected in intercostal muscles of newborn animals

A relational model for confined separation logic

Confined separation logic is a new extension to separation logic designed to deal with problems involving dangling references within shared mutable structures. In par- ticular, it allows for reasoning about confinement in object- oriented programs. In this paper, we discuss the semantics of such an extension by defining a relational model for the overall logic, parametric on the shapes of both the store and the heap. This model provides a simple and elegant interpretation of the new confinement connectives and helps in seeking for duals. A number of properties of this logic are proved calculationally.Supported by NNSFC (No. 60573081

Advances in primary large B-cell lymphoma of immune-privileged sites

Primary large B-cell lymphoma of immune-privileged sites (IP-LBCL) encompasses a spectrum of relatively rare aggressive B-cell lymphomas, such as primary central nervous system lymphoma (PCNSL), primary testicular large B-cell lymphoma (PTL), and primary vitreoretinal large B-cell lymphoma (PVRL). Macroscopically, the development of IPI-LBCL may be associated with the dysfunction of meningeal lymphatic vessels (mLVs) and the perivascular channel system formed by astrocytes. Microscopically, mutation in MYD88 and CD79B genes plays a pivotal role in the pathogenesis of IP-LBCL. Pathological examination remains the cornerstone for establishing a diagnosis of IP-LBCL. Moreover, traditional imaging is now supplemented by a suite of advanced diagnostic methods, including cytological, genetic, immunological, multiple omics, and molecular biological, which collectively enhance the diagnostic accuracy of IP-LBCL. Despite these advancements, the high recurrence rates and attendant high mortality rates pose significant challenges to achieving long-term survival in IP-LBCL patients. However, the emergence of novel therapeutic agents, such as Bruton’s tyrosine kinase inhibitors (BTKi), immune checkpoint inhibitors, immunomodulators, and anti-CD19 chimeric antigen receptor T (CAR-T) cell therapy, has offered promising new avenues for the treatment of IP-LBCL, demonstrating remarkable anti-tumor efficacy in recent years. This review delves into the epidemiology, pathogenesis mechanisms, diagnosis approaches, therapeutic strategies, and prognosis factors associated with IP-LBCL. It meticulously examines the parallels and divergences between the National Comprehensive Cancer Network (NCCN) and European Society for Medical Oncology (ESMO) guidelines, enhancing the professional comprehension of the complexities inherent to IP-LBCL

An atlas of DNA methylomes in porcine adipose and muscle tissues

It is evident that epigenetic factors, especially DNA methylation, have essential roles in obesity development. Here, using pig as a model, we investigate the systematic association between DNA methylation and obesity. We sample eight variant adipose and two distinct skeletal muscle tissues from three pig breeds living within comparable environments but displaying distinct fat level. We generate 1,381 Gb of sequence data from 180 methylated DNA immunoprecipitation libraries, and provide a genome-wide DNA methylation map as well as a gene expression map for adipose and muscle studies. The analysis shows global similarity and difference among breeds, sexes and anatomic locations, and identifies the differentially methylated regions. The differentially methylated regions in promoters are highly associated with obesity development via expression repression of both known obesity-related genes and novel genes. This comprehensive map provides a solid basis for exploring epigenetic mechanisms of adipose deposition and muscle growth

OPTOFLUIDIC PHOTONIC CRYSTAL PLATFORM FOR LABEL-FREE DETECTION AND GAS SENSING

Photonic crystals (PhCs) based label-free sensing technology has great potential as a highly sensitive, high-throughput, and compact that has vast applications in biomedical research, healthcare, pharmaceuticals, environmental security, and battlefield to detect target analytes in either liquid or vapor phase. The PhC refers to a heterogeneous structure composed of a periodic arrangement of low-loss dielectric materials with contrasting refractive index (RI). Such a structure constrains the light propagation in certain ways such that the optical properties of the PhC are particularly sensitive to changes in RI, which in turn makes them useful for sensing purposes, since the interaction of target analytes with light causes the change of local RI. Most of the studies reported so far involved micro-cavities into PhCs to achieve high quality factor, and hence better sensing performance. The in-plane light coupling method associated with micro-cavities increased the alignment challenge and made it difficult for system miniaturization. To meet this challenge, two-dimensional (2D) photonic crystal slab (PCS) is studied in this dissertation. In 2D PCS, light can be confined to in-plane guided modes by the higher RI dielectric material without coupling to externally incident beam, or can be confined to guided resonance modes in the slab where coupling to externally incident beam is allowed. Fano resonance in 2D PCS arises from the coupling of in-plane guided resonance modes above the light line to the out-of-the-plane radiation modes due to phase-matching provided by the periodic lattice structure. It is promising to employ Fano resonance in 2D PCS for sensing applications, since it provides an efficient way to channel light from within the slab to the external environment. Furthermore, Fano resonance results in asymmetric Fano lineshape in the reflection and transmission spectrum, featuring a sharp peak-to-dip transition in contrast to the conventional symmetric Lorentzian lineshape in other resonance sensors. This sharp transition in Fano lineshape is advantageous for extracting small spectral shift induced from small RI change, hence, more sensitive detection can be achieved. For bulk liquid sensing, both single-layer and coupled double-layer PCS are simulated using Fourier modal method (FMM) and finite-difference time-domain (FDTD) method, which provides guidelines for future sensor design. And then the optofluidic sensing platform based on both single-layer and coupled double-layer PCS is built and the sensor performance is characterized with various concentrations of ethanol/deionized water mixture using surface normal measurement system. In the chemical vapor detection, PCS vapor sensing platform is developed by coating vapor sensitive polymer onto PCS surface. The interaction between polymer and vapor analytes results in the polymer thickness and/or RI change, which leads to Fano resonance spectral shift. The capability of vapor sensing is demonstrated with representative vapor analytes, and the detection specificity is realized by coating PCS with different vapor absorbing polymers. Moreover, theoretical analysis using FMM and FDTD method is performed which gives guidelines to optimize the future designs of the PCS based vapor sensor