Observation of Spontaneous Brillouin Cooling

While radiation-pressure cooling is well known, the Brillouin scattering of light from sound is considered an acousto-optical amplification-only process. It was suggested that cooling could be possible in multi-resonance Brillouin systems when phonons experience lower damping than light. However, this regime was not accessible in traditional Brillouin systems since backscattering enforces high acoustical frequencies associated with high mechanical damping. Recently, forward Brillouin scattering in microcavities has allowed access to low-frequency acoustical modes where mechanical dissipation is lower than optical dissipation, in accordance with the requirements for cooling. Here we experimentally demonstrate cooling via such a forward Brillouin process in a microresonator. We show two regimes of operation for the Brillouin process: acoustical amplification as is traditional, but also for the first time, a Brillouin cooling regime. Cooling is mediated by an optical pump, and scattered light, that beat and electrostrictively attenuate the Brownian motion of the mechanical mode.Comment: Supplementary material include

Potential Sensitivity of Gamma-Ray Burster Observations to Wave Dispersion in Vacuo

The recent confirmation that at least some gamma-ray bursters (GRBs) are indeed at cosmological distances raises the possibility that observations of these could provide interesting constraints on the fundamental laws of physics. Here we demonstrate that the fine-scale time structure and hard spectra of GRB emissions are very sensitive to the possible dispersion of electromagnetic waves in vacuo with velocity differences \delta v \sim E/E_{\QG}, as suggested in some approaches to quantum gravity. A simple estimate shows that GRB measurements might be sensitive to a dispersion scale $E_{QG}$ comparable to the Planck energy scale $E_{P} \sim 10^{19}$ GeV, sufficient to test some of these theories, and we outline aspects of an observational programme that could address this goal.Comment: LaTex. 9 pages. Version accepted for publication in Nature. (A few changes to the reference list. Additional comments on the analyticity properties of the dispersion law.

Actuation of Micro-Optomechanical Systems Via Cavity-Enhanced Optical Dipole Forces

We demonstrate a new type of optomechanical system employing a movable, micron-scale waveguide evanescently-coupled to a high-Q optical microresonator. Micron-scale displacements of the waveguide are observed for milliwatt(mW)-level optical input powers. Measurement of the spatial variation of the force on the waveguide indicates that it arises from a cavity-enhanced optical dipole force due to the stored optical field of the resonator. This force is used to realize an all-optical tunable filter operating with sub-mW control power. A theoretical model of the system shows the maximum achievable force to be independent of the intrinsic Q of the optical resonator and to scale inversely with the cavity mode volume, suggesting that such forces may become even more effective as devices approach the nanoscale.Comment: 4 pages, 5 figures. High resolution version available at (http://copilot.caltech.edu/publications/CEODF_hires.pdf). For associated movie, see (http://copilot.caltech.edu/research/optical_forces/index.htm

Global effect of the COVID-19 pandemic on paediatric cancer care: a cross-sectional study

BACKGROUND: Although mortality due to COVID-19 has been reportedly low among children with cancer, changes in health-care services due to the pandemic have affected cancer care delivery. This study aimed to assess the effect of the COVID-19 pandemic on childhood cancer care worldwide. METHODS: A cross-sectional survey was distributed to paediatric oncology providers worldwide from June 22 to Aug 21, 2020, through the St Jude Global Alliance and International Society for Paediatric Oncology listservs and regional networks. The survey included 60 questions to assess institution characteristics, the number of patients diagnosed with COVID-19, disruptions to cancer care (eg, service closures and treatment abandonment), adaptations to care, and resources (including availability of clinical staff and personal protective equipment). Surveys were included for analysis if respondents answered at least two thirds of the items, and the responses were analysed at the institutional level. FINDINGS: Responses from 311 health-care professionals at 213 institutions in 79 countries from all WHO regions were included in the analysis. 187 (88%) of 213 centres had the capacity to test for SARS-CoV-2 and a median of two (range 0-350) infections per institutution were reported in children with cancer. 15 (7%) centres reported complete closure of paediatric haematology-oncology services (median 10 days, range 1-75 days). Overall, 2% (5 of 213) of centres were no longer evaluating new cases of suspected cancer, while 43% (90 of 208) of the remaining centers described a decrease in newly diagnosed paediatric cancer cases. 73 (34%) centres reported increased treatment abandonment (ie, failure to initiate cancer therapy or a delay in care of 4 weeks or longer). Changes to cancer care delivery included: reduced surgical care (153 [72%]), blood product shortages (127 [60%]), chemotherapy modifications (121 [57%]), and interruptions to radiotherapy (43 [28%] of 155 institutions that provided radiotherapy before the pandemic). The decreased number of new cancer diagnoses did not vary based on country income status (p=0·14). However, unavailability of chemotherapy agents (p=0·022), treatment abandonment (p<0·0001), and interruptions in radiotherapy (p<0·0001) were more frequent in low-income and middle-income countries than in high-income countries. These findings did not vary based on institutional or national numbers of COVID-19 cases. Hospitals reported using new or adapted checklists (146 [69%] of 213), processes for communication with patients and families (134 [63%]), and guidelines for essential services (119 [56%]) as a result of the pandemic. INTERPRETATION: The COVID-19 pandemic has considerably affected paediatric oncology services worldwide, posing substantial disruptions to cancer diagnosis and management, particularly in low-income and middle-income countries. This study emphasises the urgency of an equitably distributed robust global response to support paediatric oncology care during this pandemic and future public health emergencies. FUNDING: American Lebanese Syrian Associated Charities. TRANSLATION: For the Spanish translation of the abstract see Supplementary Materials section

Trends in healthcare utilization among older Americans with colorectal cancer: A retrospective database analysis

<p>Abstract</p> <p>Background</p> <p>Analyses of utilization trends (cost drivers) allow us to understand changes in colorectal cancer (CRC) costs over time, better predict future costs, identify changes in the use of specific types of care (eg, hospice), and provide inputs for cost-effectiveness models. This retrospective cohort study evaluated healthcare resource use among US Medicare beneficiaries diagnosed with CRC between 1992 and 2002.</p> <p>Methods</p> <p>Cohorts included patients aged 66+ newly diagnosed with adenocarcinoma of the colon (n = 52,371) or rectum (n = 18,619) between 1992 and 2002 and matched patients from the general Medicare population, followed until death or December 31, 2005. Demographic and clinical characteristics were evaluated by cancer subsite. Resource use, including the percentage that used each type of resource, number of hospitalizations, and number of hospital and skilled nursing facility days, was evaluated by stage and subsite. The number of office, outpatient, and inpatient visits per person-year was calculated for each cohort, and was described by year of service, subsite, and treatment phase. Hospice use rates in the last year of life were calculated by year of service, stage, and subsite for CRC patients who died of CRC.</p> <p>Results</p> <p>CRC patients (mean age: 77.3 years; 44.9% male) used more resources than controls in every category (<it>P </it>< .001), with the largest differences seen in hospital days and home health use. Most resource use (except hospice) remained relatively steady over time. The initial phase was the most resource intense in terms of office and outpatient visits. Hospice use among patients who died of CRC increased from 20.0% in 1992 to 70.5% in 2004, and age-related differences appear to have evened out in later years.</p> <p>Conclusion</p> <p>Use of hospice care among CRC decedents increased substantially over the study period, while other resource use remained generally steady. Our findings may be useful for understanding CRC cost drivers, tracking trends, and forecasting resource needs for CRC patients in the future.</p

Memory development: implications for adults recalling childhood experiences in the courtroom

Adults frequently provide compelling, detailed accounts of early childhood experiences in the courtroom. Judges and jurors are asked to decide guilt or innocence based solely on these decades-old memories using 'common sense' notions about memory. However, these notions are not in agreement with findings from neuroscientific and behavioural studies of memory development. Without expert guidance, judges and jurors may have difficulty in properly adjudicating the weight of memory evidence in cases involving adult recollections of childhood experiences

Regulation of Anthrax Toxin-Specific Antibody Titers by Natural Killer T Cell-Derived IL-4 and IFNγ

Activation of Natural Killer-like T cells (NKT) with the CD1d ligand α-GC leads to enhanced production of anthrax toxin protective Ag (PA)-neutralizing Abs, yet the underlying mechanism for this adjuvant effect is not known. In the current study we examined the role of Th1 and Th2 type responses in NKT-mediated enhancement of antibody responses to PA. First, the contribution of IL-4 and IFNγ to the production of PA-specific toxin-neutralizing Abs was examined. By immunizing C57Bl/6 controls IL-4−/− mice and IFNγ−/− mice and performing passive serum transfer experiments, it was observed that sera containing PA-specific IgG1, IgG2b and IgG2c neutralized toxin in vitro and conferred protection in vivo. Sera containing IgG2b and IgG2c neutralized toxin in vitro but were not sufficient for protection in vivo. Sera containing IgG1 and IgG2b neutralized toxin in vitro and conferred protection in vivo. IgG1 therefore emerged as a good correlate of protection. Next, C57Bl/6 mice were immunized with PA alone or PA plus a Th2-skewing α-GC derivative known as OCH. Neutralizing PA-specific IgG1 responses were modestly enhanced by OCH in C57Bl/6 mice. Conversely, IgG2b and IgG2c were considerably enhanced in PA/OCH-immunized IL-4−/− mice but did not confer protection. Finally, bone marrow chimeras were generated such that NKT cells were unable to express IL-4 or IFNγ. NKT-derived IL-4 was required for OCH-enhanced primary IgG1 responses but not recall responses. NKT-derived IL-4 and IFNγ also influenced primary and recall IgG2b and IgG2c titers. These data suggest targeted skewing of the Th2 response by α-GC derivatives can be exploited to optimize anthrax vaccination

Non-Invasive Microstructure and Morphology Investigation of the Mouse Lung: Qualitative Description and Quantitative Measurement

BACKGROUND: Early detection of lung cancer is known to improve the chances of successful treatment. However, lungs are soft tissues with complex three-dimensional configuration. Conventional X-ray imaging is based purely on absorption resulting in very low contrast when imaging soft tissues without contrast agents. It is difficult to obtain adequate information of lung lesions from conventional X-ray imaging. METHODS: In this study, a recently emerged imaging technique, in-line X-ray phase contrast imaging (IL-XPCI) was used. This powerful technique enabled high-resolution investigations of soft tissues without contrast agents. We applied IL-XPCI to observe the lungs in an intact mouse for the purpose of defining quantitatively the micro-structures in lung. FINDINGS: The three-dimensional model of the lung was successfully established, which provided an excellent view of lung airways. We highlighted the use of IL-XPCI in the visualization and assessment of alveoli which had rarely been studied in three dimensions (3D). The precise view of individual alveolus was achieved. The morphological parameters, such as diameter and alveolar surface area were measured. These parameters were of great importance in the diagnosis of diseases related to alveolus and alveolar scar. CONCLUSION: Our results indicated that IL-XPCI had the ability to represent complex anatomical structures in lung. This offered a new perspective on the diagnosis of respiratory disease and may guide future work in the study of respiratory mechanism on the alveoli level