Behavioral universality across size scales: Glassy materials are characterized by a lack of long-range order, whether at the atomic level or at much larger length scales. But to what extent is their commonality in the behavior retained at these different scales? Cubuk et al. used experiments and simulations to show universality across seven orders of magnitude in length. Particle rearrangements in such systems are mediated by defects that are on the order of a few particle diameters. These rearrangements correlate with the material's softness and yielding behavior. Science , this issue p. 1033

Diffuse correlation spectroscopy (DCS) is an emerging optical modality used to measure cortical cerebral blood flow. This outlook presents a brief overview of the technology, summarizing the advantages and limitations of the method, and describing its recent applications to animal, adult, and infant cohorts. At last, the paper highlights future applications where DCS may play a pivotal role individualizing patient management and enhancing our understanding of neurovascular coupling, activation, and brain development.

Breast cancer is one of the most common cancers among women. Approximately one in eight women in the United States will develop breast cancer during their lifetime, and, of these, about 20–30% will ultimately die of the disease.¹ Thus, early detection and accurate diagnosis of breast cancer are important. Existing clinical methods used for breast cancer screening and diagnosis, however, have drawbacks. X-ray mammography, for example, has an $\sim 22\%$ false-negative rate in women under 50² and sometimes cannot accurately distinguish between benign and malignant tumors.³ Even though the false-positive rate of individual mammography is less than 10%,^{4, 5} 18% of women with no breast cancer will have undergone a biopsy after 10 mammograms.⁵ Techniques such as ultrasound and magnetic resonance imaging (MRI) are sometimes used in addition to X-ray mammography, but they have limitations such as high cost, low throughput, limited specificity (MRI), and low sensitivity (ultrasound). Thus, new methods are needed to detect cancers earlier for treatment, to detect cancers missed by mammography,^{6, 7, 8} to reduce the false-positive rate,^{4, 5} and to monitor tumor progression during cancer therapy.