On Jumps and Arch Effects in Natural Resource Prices. An Application to Stumpage Prices from Pacific Northwest National Forests

Models used for natural resources prices usually preclude the possibility of large changes (jumps) resulting from discrete, unexpected events. To test for the presence of jumps and ARCH effects, we propose to use bounds and bootstrap test techniques, thus solving the unidentified nuisance parameter problem. We apply this approach to stumpage price time series from the Pacific Northwest and find evidence of jumps and ARCH effects. Using real options, we then develop a stopping model to assess the impact of neglecting jumps on the decision to harvest old-growth timber. Our numerical results show the importance of modeling jumps explicitly.Jump processes, ARCH, Bootstrap, Stumpage prices, Real options

On Jumps and ARCH Effects in Natural Resource Prices. An Application to Stumpage Prices from Pacific Northwest National Forests

Models use for natural resources prices usually preclude the possibility of large changes (jumps) resulting from discrete, unexpected events. To test for the presence of jumps and ARCH effects, we propose to use bounds and bootstrap test techniques, thus solving the unidentified nuisance parameter problem. We apply this approach to stumpage price time series from the Pacific Northwest and find evidence of jumps and ARCH effects. Using real options, we then develop a stopping model to assess the impact of neglecting jumps on the decision to harvest old-growth timber. Our numerical results show the importance of modeling jumps explicitly.Jum Processes, ARCH, Bootstrap, Stumpage Prices, Real Options

Simulation-Based Exact Tests with Unidentified Nuisance Parameters under the Null Hypothesis : the Case of Jumps Tests in Model with Conditional Heteroskedasticity

We use the Monte-Carlo (MC) test technique to find valid p-values when testing for discontinuities in jump-diffusion models. While the distribution of the LR statistic for this test is typically non-standard, we show that the MC p-value is finite sample exact if no other (identified) nuisance parameter is present. Otherwise, we derive nuisance-parameter free bounds and obtain exact bounds p-values. We illustrate our approach on four classes of jump-diffusion models we use to model spot prices of copper, nickel, gold, and crude oil. We find significant jumps in all weekly time series and in a few monthly time series.Monte-Carlo test, bounds test, discontinuous process, conditional heteroscedasticity

Untwisting moir\'e physics: Almost ideal bands and fractional Chern insulators in periodically strained monolayer graphene

Moir\'e systems have emerged in recent years as a rich platform to study strong correlations. Here, we will discuss a simple, experimentally feasible setup based on periodically strained graphene that reproduces several key aspects of twisted moir\'e heterostructures -- but without introducing a twist. We consider a monolayer graphene sheet subject to a $C_2$-breaking periodic strain-induced psuedomagnetic field (PMF) with period $L_M \gg a$, along with a scalar potential of the same period. This system has {\it almost ideal} flat bands with valley-resolved Chern number $\pm 1$, where the deviation from ideal band geometry is analytically controlled and exponentially small in the dimensionless ratio $(L_M/l_B)^2$ where $l_B$ is the magnetic length corresponding to the maximum value of the PMF. Moreover, the scalar potential can tune the bandwidth far below the Coulomb scale, making this a very promising platform for strongly interacting topological phases. Using a combination of strong-coupling theory and self-consistent Hartree fock, we find quantum anomalous Hall states at integer fillings. At fractional filling, exact diagonaliztion reveals a fractional Chern insulator at parameters in the experimentally feasible range. Overall, we find that this system has larger interaction-induced gaps, smaller quasiparticle dispersion, and enhanced tunability compared to twisted graphene systems, even in their ideal limit.Comment: 5 pages + supplemen

An Extensive Set of Kinematic and Kinetic Data for Individuals with Intact Limbs and Transfemoral Prosthesis Users

This paper introduces an extensive human motion data set for typical activities of daily living. These data are crucial for the design and control of prosthetic devices for transfemoral prosthesis users. This data set was collected from seven individuals, including five individuals with intact limbs and two transfemoral prosthesis users. These data include the following types of movements: (1) walking at three different speeds; (2) walking up and down a 5-degree ramp; (3) stepping up and down; (4) sitting down and standing up. We provide full-body marker trajectories and ground reaction forces (GRFs) as well as joint angles, joint velocities, joint torques, and joint powers. This data set is publicly available at the website referenced in this paper. Data from flexion and extension of the hip, knee, and ankle are presented in this paper. However, the data accompanying this paper (available on the internet) include 46 distinct measurements and can be useful for validating or generating mathematical models to simulate the gait of both transfemoral prosthesis users and individuals with intact legs

PARP Inhibitors for the Treatment of BRCA1/2-Mutated Metastatic Breast Cancer: A Systematic Review and Meta-analysis

BACKGROUND: The PARP inhibitors (PARPis) olaparib and talazoparib are currently approved for the treatment of deleterious germline BRCA1/2-mutated (gBRCA+) metastatic breast cancer (MBC). These approvals were based on improvements in progression-free survival (PFS) observed in two randomized controlled trials (RCTs). Other PARPis, such as veliparib and niraparib, have also been studied. We conducted this meta-analysis of RCTs to assess the PFS and overall survival (OS) benefits of PARPis in gBRCA + MBC. METHODS: We performed a systematic search for RCTs using the Cochrane Library, PubMed, Embase, and Web of Science databases up to March 2021. Only phase II and III RCTs evaluating PFS and OS for PARPis alone or in combination with chemotherapy (CT) and comparing the findings with standard CT were included in this meta-analysis. Pooled analysis of the hazard ratio (HR) was performed with RevMan v5.4 using a random effects method. RESULTS: Five RCTs with a total of 1563 BRCA-mutated MBC patients were included in this meta-analysis. Temozolomide was used in the treatment arm in the BROCADE trial. Since temozolomide has limited effects on breast cancer, this arm was excluded from our meta-analysis. A statistically significant increase in PFS was observed in the PARPi group compared to the standard CT group (HR, 0.64; 95% CI, 0.56-0.74; P \u3c 0.00001). However, the differences in OS did not reach statistical significance (HR, 0.89; 95% CI, 0.77-1.02; P = 0.09). Moreover, differences were not observed in the adverse event profile between the two groups (odds ratio, 1.18; 95% CI, 0.84-1.64; P = 0.33). CONCLUSION: The results of our meta-analysis confirm the previously reported PFS benefit of PARPis over standard CT. PARPis lead to superior PFS in gBRCA + MBC when used alone or in combination with standard CT. The OS benefit is similar between PARPis and standard CT. Ongoing trials are evaluating the benefits of PARPis in early stage gBRCA + BC

Treatment algorithms for high responders: What we can learn from randomized controlled trials, real-world data and models

A high ovarian response to conventional ovarian stimulation (OS) is characterized by an increased number of follicles and/or oocytes compared with a normal response (10-15 oocytes retrieved). Ac-cording to current definitions, a high response can be diagnosed before oocyte pick-up when >18-20 follicles >= 11-12 mm are observed on the day of ovulation triggering; high response can be diagnosed after oocyte pick-up when >18-20 oocytes have been retrieved. Women with a high response are also at high risk of early ovarian hyper-stimulation syndrome (OHSS)/or late OHSS after fresh embryo transfers. Women at risk of high response can be diagnosed before stimulation based on several indices, including ovarian reserve markers (anti-Mullerian hormone [AMH] and antral follicle count [AFC], with cutoff values indicative of a high response in patients with PCOS of >3.4 ng/mL for AMH and >24 for AFC). Owing to the high proportion of high responders who are at the risk of developing OHSS (up to 30%), this educational article provides a framework for the identification and management of patients who fall into this category. The risk of high response can be greatly reduced through appropriate management, such as individualized choice of the gonadotropin starting dose, dose adjustment based on hormonal and ultrasound monitoring during OS, the choice of down-regulation protocol and ovulation trigger, and the choice between fresh or elective frozen embryo transfer. Appropriate management strategies still need to be defined for women who are predicted to have a high response and those who have an unex-pected high response after starting treatment.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4.0/)

Unconventional sequence of correlated Chern insulators in magic-angle twisted bilayer graphene

The interplay between strong electron-electron interactions and band topology can lead to novel electronic states that spontaneously break symmetries. The discovery of flat bands in magic-angle twisted bilayer graphene (MATBG) with nontrivial topology has provided a unique platform in which to search for new symmetry-broken phases. Recent scanning tunneling microscopy and transport experiments have revealed a sequence of topological insulating phases in MATBG with Chern numbers $C=\pm 3, \, \pm 2, \, \pm 1$ near moir\'e band filling factors $\nu = \pm 1, \, \pm 2, \, \pm 3$, corresponding to a simple pattern of flavor-symmetry-breaking Chern insulators. Here, we report high-resolution local compressibility measurements of MATBG with a scanning single electron transistor that reveal a new sequence of incompressible states with unexpected Chern numbers observed down to zero magnetic field. We find that the Chern numbers for eight of the observed incompressible states are incompatible with the simple picture in which the $C= \pm 1$ bands are sequentially filled. We show that the emergence of these unusual incompressible phases can be understood as a consequence of broken translation symmetry that doubles the moir\'e unit cell and splits each $C=\pm 1$ band into a $C=\pm 1$ band and a $C=0$ band. Our findings significantly expand the known phase diagram of MATBG, and shed light onto the origin of the close competition between different correlated phases in the system