Science

I claim that one way thought experiments contribute to scientific progress is by increasing scientific understanding. Understanding does not have a currently accepted characterization in the philosophical literature, but I argue that we already have ways to test for it. For instance, current pedagogical practice often requires that students demonstrate being in either or both of the following two states: 1) Having grasped the meaning of some relevant theory, concept, law or model, 2) Being able to apply that theory, concept, law or model fruitfully to new instances. Three thought experiments are presented which have been important historically in helping us pass these tests, and two others that cause us to fail. Then I use this operationalization of understanding to clarify the relationships between scientific thought experiments, the understanding they produce, and the progress they enable. I conclude that while no specific instance of understanding (thus conceived) is necessary fo...

Biological functions rely on ordered structures and intricately controlled collective dynamics. This order in living systems is typically established and sustained by continuous dissipation of energy. The emergence of collective patterns of motion is unique to nonequilibrium systems and is a manifestation of dynamic steady states. Mechanical resilience of animal cells is largely controlled by the actomyosin cortex. The cortex provides stability but is, at the same time, highly adaptable due to rapid turnover of its components. Dynamic functions involve regulated transitions between different steady states of the cortex. We find that model actomyosin cortices, constructed to maintain turnover, self-organize into distinct nonequilibrium steady states when we vary cross-link density. The feedback between actin network structure and organization of stress-generating myosin motors defines the symmetries of the dynamic steady states. A marginally cross-linked state displays divergence-fre...

In nuclear magnetic resonance (NMR), the lifetimes of long-lived states (LLSs) are exquisitely sensitive to their environment. However, the number of molecules where such states can be excited has hitherto been rather limited. Here, it is shown that LLSs can be readily excited in many common molecules that contain two or more neighboring CH 2 groups. Accessing such LLSs does not require any isotopic enrichment, nor does it require any stereogenic centers to lift the chemical equivalence of CH 2 protons. LLSs were excited in a variety of metabolites, neurotransmitters, vitamins, amino acids, and other molecules. One can excite LLSs in several different molecules simultaneously. In combination with magnetic resonance imaging, LLSs can reveal a contrast upon noncovalent binding of ligands to macromolecules. This suggests new perspectives to achieve high-throughput parallel drug screening by NMR.

UZUME. Junichi Haruyama , Isao Kawano , Toshiyuki Nishibori , Takahiro Iwata , Yukio Yamamoto , Kazuhito Shimada , Keiko Yamamoto , Toshiaki Hasenaka , Tomokatsu Morota , Masaki N. Nishino , Ko Hashizume , Motomaro Shirao , Goro Komatsu , Nobuyuki Hasebe , Hisayoshi Shimizu , Kensei Kobayashi , Shinichi Yokobori , Yohei Miyake , Yuichi Michikawa , Takeshi Tsuji , Reina Shinoda 1) . JAXA, Japan, Kumamoto University, Japan, 3) Nagoya University, Japan, 4) Osaka University, Japan, 5) Planetary Geology Institute, Japan, 6) Università d’Annunzio, Italy, 7) Waseda University, Japan, 8) University of Tokyo, Japan, 9) Yokohama National University, Japan,Tokyo University of Pharmacy and Life Sciences, Japan, 11) Kobe University, Japan, 12) National Institute for Environmental Studies, Japan, Tokai University, Japan. E-mail:haruyama.junichi_at_jaxa.jp.

Cardiac dysfunction is a common extrapulmonary complication of severe influenza virus infection. Prevailing models propose that influenza-associated heart dysfunction is indirectly triggered by cytokine mediated cardiotoxicity downstream of the inflamed lung, rather than by direct infection of cardiac tissue. To test the etiology of cardiac dysfunction resulting from influenza virus infection, we generated a novel recombinant H1N1 influenza A virus that was attenuated in cardiomyocytes by incorporation of target sequences for miRNAs expressed specifically in that cell type (miR133b and miR206). Compared with control virus, mice infected with the miR-targeted virus had significantly reduced heart viral titers, confirming cardiac attenuation of viral replication. The miR-targeted virus, however, was fully replicative and inflammatory in lungs when compared to control virus, and induced similar systemic weight loss. The miR-targeted virus induced considerably lower levels of cardiac ar...

The rapid growth of deformable and stretchable electronics calls for a deformable and stretchable power source. We report a scalable approach for energy harvesters and self-powered sensors that can be highly deformable and stretchable. With conductive liquid contained in a polymer cover, a shape-adaptive triboelectric nanogenerator (saTENG) unit can effectively harvest energy in various working modes. The saTENG can maintain its performance under a strain of as large as 300%. The saTENG is so flexible that it can be conformed to any three-dimensional and curvilinear surface. We demonstrate applications of the saTENG as a wearable power source and self-powered sensor to monitor biomechanical motion. A bracelet-like saTENG worn on the wrist can light up more than 80 light-emitting diodes. Owing to the highly scalable manufacturing process, the saTENG can be easily applied for large-area energy harvesting. In addition, the saTENG can be extended to extract energy from mechanical motion...

Nearly 50 years ago, theoretical physicists proposed that a field permeates the universe and gives energy to the vacuum. This field was required to explain why some, but not all, fundamental particles have mass. Numerous precision measurements during recent decades have provided indirect support for the existence of this field, but one crucial prediction of this theory has remained unconfirmed despite 30 years of experimental searches: the existence of a massive particle, the standard model Higgs boson. The ATLAS experiment at the Large Hadron Collider at CERN has now observed the production of a new particle with a mass of 126 giga–electron volts and decay signatures consistent with those expected for the Higgs particle. This result is strong support for the standard model of particle physics, including the presence of this vacuum field. The existence and properties of the newly discovered particle may also have consequences beyond the standard model itself.

We examine the possibility that some weak interaction cross sections become large at very high energies. Such effects could Iead to observable weak interaction phenomena in very high energy pp and p~ colliding beams. Apart from direct production of W's and Z's, the possibility of observable weak effects requires the Higgs mass to be much larger than the mass of the vector bosons. However, for feasible experiments such effects are suppressed in many popular gauge theories, and we expect that observable weak cross sections will not get large at high energies. Theories with more than one Higgs boson may allow large observable effects. * Research supported in part by the Department of Energy. * We have recently discussed in detail the possibility that parity-violating effects signalling weak interactions can be studied at high energies and large PT by detecting hadron resonance decays and A's. Such methods should allow one to detect W's and Z's and other "weak" cross sections, and to establish that they are weak interaction effects. See ref. .

Controlling interfaces of phase-separating fluid mixtures is key to the creation of diverse functional soft materials. Traditionally, this is accomplished with surface-modifying chemical agents. Using experiment and theory, we studied how mechanical activity shapes soft interfaces that separate an active and a passive fluid. Chaotic flows in the active fluid give rise to giant interfacial fluctuations and noninertial propagating active waves. At high activities, stresses disrupt interface continuity and drive droplet generation, producing an emulsion-like active state composed of finite-sized droplets. When in contact with a solid boundary, active interfaces exhibit nonequilibrium wetting transitions, in which the fluid climbs the wall against gravity. These results demonstrate the promise of mechanically driven interfaces for creating a new class of soft active matter.

The arguments of Poinar et al . neither challenge our conclusions nor would contribute to the verification of our data. We counter their questions about the authenticity of our ancient DNA results and the reliability of the radiocarbon data and stand by the conclusion that our data provide strong evidence of pre-Clovis Native Americans.

Our project "Generic Portals" 1 focuses on the possibilities and problems created by the usage of web-technologies to support web-based Digital Library applications. We observe a divergence of services in the sphere of structured resources and scientific libraries´ services. Publications in the form of digital resources have introduced new dynamics into the information exchange in the scientific communities. The changes in the publication process are formed by so-called structured resources, whereas the resource can be seen as an encapsulated object. For the exchange of information we have only to know the interface of the structured resource in detail. W3C has published a working draft which includes a language named Web Service Description Language (WSDL) for describing interfaces of services. A Web service interface is a shared connection between functional components of applications. We consider the requirements for the integration of DL-applications via Web services. We present an adapted process model for supply of DL-oriented Web services. Further we present a component-based approach to relate researchers´ activities to so-called DL-oriented Web services. We obtain criteria for the description of DL-oriented Web services based on the researchers´ working process. Finally, we present a brief overview what kind of Web technologies might be reused for a prototypical implementation of DL-oriented Web services.

The article discusses changes in scientific work (academic and applied) associated with new potentials, but also coercions of information technologies. Background for this interest is the experience gained in several digital library projects that inclinations and willingness to use these technical possibilities is much less common than the developers of these systems, and we all, tended to think in recent years. This seems to be true even in those scientific disciplines which were and are at the forefront of the development, e.g. physics, mathematics, etc. The background for this observation is discussed looking at general economic and social changes, viewing the environments of work in the scientific sphere, the contents and their quantity and quality of supply in scientific IT systems, the user side in their communities of practice, and the technological and organizational basis of scientific information. Some strategic issues to improve the situation are discussed in the final part of the paper. In the last thirty years the role of knowledge, and especially of scientific knowledge and its information basis, has changed dramatically in the international economy and society. The new "Informational Capitalism" or "Digital Capitalism" (Schiller 1999) is characterized by a new stage of globalization, implying new forms of markets and organization, and by a dramatic take-off and intensification of overall informatization. In general, the new capacity of informational capitalism is the development of socio-technical systems which generate, communicate and process information around the globe in real-time. For society and organizations, the "network society" (Castells 1996) entails an increasing role of network forms of cooperation and organization, characterized by the creation of "horizontal" organizations with flat hierarchies, decentralized structures, focussed on continuous re-engineering of their resources with the concentration on their key competences and continuous rationalization along the value creation chain (cf. Knoke 2001, ch. 1). The new type of network or virtual organization brings the market as close as possible to every department, project, work group, and individual -it implies a "new immediacy" of the economy, an increased directness of economic forces shaping the conditions of the single economic unit (cf. Schmiede 2003;. Network structures play an increasing role on various levels. The new forms of network cooperation depend more or less on the digital information and

Scaling Spindle Size The difficulty of modulating cell size in vivo has made it hard to test hypotheses for organelle size scaling during development. To this end, Hazel et al. (p. 853 ) and Good et al. (p. 856 ) developed microfluidic systems in which cytoplasmic extracts are encapsulated in compartments with definable size. The size of mitotic spindles assembled within cell-free extracts scaled with the volume of the compartment within which the spindle assembled. The findings suggest that the diminished availability of cytoplasmic components, notably tubulin, concomitant with cell size reduction, prescribes a smaller spindle size.

Applications are invited for one of the international Post-Doctoral Research Fellowships set up by the Gillette Company to promote the international exchange of scientific and technical workers. The present Fellowship is tenable in the Department of Physics of the University of Southampton under the direction of Dr. H.G. Jerrard or Dr. B.J. Hopkins. Applicants should hold a higher degree, or possess 3-4 years relevant post-graduate research experience. This Fellowship is open to nationals of the UK, other Western European countries or the United States, or Canada. The Fellow will be expected to undertake a study of surfaces and of films, both metallic and dielectric (including organic polymers) deposited under, and subject to, a variety of environ mental conditions. The applicant should submit his own proposal for a programme of work. The available techniques include LEED, RHEED, Auger spectroscopy, ellipsometry, electron microscopy and work function methods. It is expected that the results of the work will be published. The Fellowship will be for one year, in the first instance, with the possibility of renewal for a further year and will carry a remuneration of £ 2,300 per annum. Applicants should be able to take up the Fellowship during 1973. Applications giving full personal particulars including curriculum vitae, and a programme proposal with names and addresses of two academic or technical referees, should be sent to: The Secretary,

utbreak alert: six students at the Chicago State Polytechnic University in Illinois have been hospitalized with severe vomiting, diarrhoea and stomach pain, as well as wheezing and difficulty in breathing. Some are in a critical condition. And the university's health centre is fielding dozens of calls from students with similar symptoms. This was the scenario that 17 third-and fourth-year undergraduates dealt with as part of an innovative virology course led by biologist Tammy Tobin at Susquehanna University in Selinsgrove, Pennsylvania. The students took on the role of federal public-health officials, and were tasked with identifying the pathogen, tracking how it spreads and figuring out how to contain and treat it -all by the end of the semester. Although the Chicago school and the cases were fictitious, says Tobin, "we tried to make it as real as possible". If students decided to run a blood test or genetic assay, Tobin would give them results consistent with enterovirus D68, a real respiratory virus. (To keep the students from just getting the answer from the Internet, she portrayed the virus as an emergent strain with previously unreported symptoms.) If they decided to send a team to Chicago, Tobin would make them look at real flight schedules and confirm that there were enough seats. Active problem-solving a deeper understanding of science than does a standard lecture. But some university lecturers are reluctant to change tack.

Now that President Reagan has endorsed the National Aeronautics and Space Administration (NASA) plan for a permanently manned space station, the issue goes to Congress: No consensus of opinion has formed there yet, but key committee staffers contacted by Science believe that approval is likely. NASA has made a vigorous case for the utility of the station (Science, 24 February, p. 793), and those members who have studied the idea are reasonably comfortable with it. However, that does not add up to a blank check. The

The new array was given the go-ahead. But congressional pressures to boost NSF funding for education led to a budget for groundbased astronomy that has not even kept pace with inflation-and that has had to absorb the entire VLBA cost to boot. Since 1984, says Vanden Bout, budgets for maintenance

science fiction" the public's amor- phous fears about what will happen when we go about "playing God." The only other witness at the hearing was French Anderson of the Na- tional Heart, Lung, and Blood Institute. Anderson at the beginning of the hearing professed himself quite satisfied with the report, but was by the end of the moming admitting to some uneasiness over the world that gene splicing is opening up. It was the "reductionism" that bothered himthe knowledge that at the most ele- mentary level the stuff of human life is interchangeable with that of all other life made him wonder "if there is any- thing unique about humanness ... if not, there is nothing wrong with gene manipulation." The prospect he found "frightening."-Constance Holden

Objective: The study was focused to assess the outcome of the Mass closure in all midline laparotomy procedure regardless of the underlying condition and to understand the outcome. Materials and methods: A prospective study was carried out on 100 patients at a Rural Hospital undergoing midline laparotomy and the closure of abdomen was performed by a non absorbable polypropylene (Prolene) suture material, in a continuous Mass closure technique followed by the rate of incidence of development of complications like surgical site infection, wound dehiscence (partial or complete) and incisional hernia were assessed and correlated with the patient related factors. Results: Surgical site infection was the most common complication encountered, followed by incisional hernia and wound dehiscence. Hypoproteienemia was significantly associated with the incidence of complications. Surgical site infection has a strongly significant association, with the incidence of development of incisional hernia as well as wound dehiscence. Conclusion: Continuous mass closure is the ideal technique for the closure of the abdomen with a non-absorbable polypropylene suture material, in the absence of patient confounding factors like hypoproteinemia and surgical site infection.

An N-acetyl-D-galactosamine-specific lectin has been isolated from the two seed forms of the hog peanut (Amphicarpaea bracteata) using an affinity support containing the synthetic type A blood group trisaccharide cY-D-GalNAc-(1,3)-[c-L-Fuc-(1,2)]-@-D-Gal (Synsorb A). The affinity-purified lectin appears to be identical in both seed types. Gel filtration on Sephadex G-200 gives a single symmetrical peak corresponding to M, 135,000. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows four subunit forms, each of which contains carbohydrate. Limited amino terminal sequencing indicates heterogeneity in two of the first 10 residues. The lectin contains no cysteine. There are four equivalent, noninteracting GalNAc binding sites per 135,000-Da molecule, having an association constant for methyl N-acetyl-cu-D-galactosaminide of 4.0 X lo4 M-l. Precipitin and hapten inhibition studies show the lectin to be specific for terminal, nonreducing D-GalNAc units, with a preference for the cu-anomer and enhanced specificity for the disaccharide, GalNAccul,3GalNAc. There is also a single adenine binding site per M, 135,000 lectin molecule with an association constant of 1.3 X lo6 M-l.

Protected conservation areas face huge challenges globally (see J. E. M. Watson et al. Nature 515, 67-73; 2014). But examples that are effectively funded and managed can be found in Namibia and in the Brazilian Amazon. In our view, these models are so successful that they could be adapted and replicated around the world. In Namibia, the Ministry of Environment and Tourism awards exclusive tourism concessions to communities that are next to protected areas and have formed conservancies. This attracts millions of dollars in infrastructure investment, empowering communities with economic activity and employment opportunities and creating strong incentives to live with and protect wildlife. The Amazon Region Protected Areas programme safeguards a staggering 15% of the Brazilian

Domain walls (DWs) in ferroelectrics are atomically sharp and can be created, erased, and reconfigured within the same physical volume of ferroelectric matrix by external electric fields. They possess a myriad of novel properties and functionalities that are absent in the bulk of the domains, and thus could become an essential element in next-generation nanodevices based on ferroelectrics. The knowledge about the structure and properties of ferroelectric DWs not only advances the fundamental understanding of ferroelectrics, but also provides guidance for the design of ferroelectric-based devices. In this article, we provide a review of structures and properties of DWs in one of the most widely studied ferroelectric systems, BiFeO3 thin films. We correlate their conductivity and photovoltaic properties to the atomic-scale structure and dynamic behaviors of DWs.

We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature ( T c ) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO 3 layers in BaTiO 3 /SrTiO 3 superlattices are not only ferroelectric (with T c as high as 250 kelvin) but also polarize the quantum paraelectric SrTiO 3 layers adjacent to them. T c was tuned by ∼500 kelvin by varying the thicknesses of the BaTiO 3 and SrTiO 3 layers, revealing the essential roles of electrical and mechanical boundary conditions for nanoscale ferroelectricity.

The domain microstructure in an epitaxial thin film of Bi4Ti3O12 on a SrTiO3(001) substrate is studied by second harmonic generation measurements. The input polarization dependence of the second harmonic signal exhibits spatial symmetries that reflect the presence of eight different domain variants present in the film. A theoretical model is presented that explains the observed symmetries and extracts quantitative information on the nonlinear optical coefficients of the material and statistics of domain variants present in the film area being probed. The following ratios of nonlinear coefficients and birefringence was determined: d12/d11=−3.498±0.171, |d26/d12|=0.365±0.010, |d26/d11|=1.273±0.036, and |nb−na|=0.101±0.018 (at 532 nm).

Use of an epitaxial conducting template has enabled the integration of epitaxial ferroelectric perovskites on silicon. The conducting template layer, LaxSr1−xTiO3 (LSTO), deposited onto (001) silicon wafers by molecular-beam epitaxy is then used to seed {001}-oriented epitaxial perovskite layers. We illustrate the viability of this approach using PbZr0.4Ti0.6O3 (PZT) as the ferroelectric layer contacted with conducting perovskite La0.5Sr0.5CoO3 (LSCO) electrodes. An important innovation that further facilitates this approach is the use of a low-temperature (450 °C) sol–gel process to crystallize the entire ferroelectric stack. Both transmission electron microscopy and x-ray diffraction analysis indicate the LSCO/PZT/LSCO/LSTO/Si heterostructures are epitaxial. The electrical response of ferroelectric capacitors (for pulse widths down to 1 μs) measured via the underlying silicon substrate is identical to measurements made using conventional capacitive coupling method, indicating the ...

Skin aging is a change in the structure of the skin which is a consequence of increasing age. Exposure to ultraviolet (UV) light, which can induce the formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) thereby damaging cells, can trigger aging. The appearance of signs of skin aging can interfere with appearance so many people start using skin care products. Human skin cells are known to synthesize and possess several types of melatonin receptors. This study aims to determine melatonin as a marker of the aging process. This research method is a systematic literature review (SLR) on journal papers published from 2014-2021. The results show that aging is associated with increased free radicals and decreased tissue antioxidant capacity and that exogenous melatonin plays a protective role in aging through its action on free radicals. The production of endogenous intracutaneous melatonin, together with topically applied exogenous melatonin and its metabolites, represent the two most powerful defense systems against external damage to the skin. Melatonin is in an optimal position to scavenge radicals and reduce levels of oxidative damage. Given the "free radical aging theory", including all its iterations, high levels of melatonin in mitochondria are expected to protect against agerelated decline in organisms. Also, there are many age-related diseases, as a contributing factor, to free radical damage. In women with aging skin, Melatonin-based creams significantly increase skin tonicity and skin hydration with a significant reduction in skin roughness, supporting the antiaging effect of the skin.

Recent behavioral experiments aimed at understanding the evolutionary foundations of human cooperation have suggested that a willingness to engage in costly punishment, even in one-shot situations, may be part of human psychology and a key element in understanding our sociality. However, because most experiments have been confined to students in industrialized societies, generalizations of these insights to the species have necessarily been tentative. Here, experimental results from 15 diverse populations show that (i) all populations demonstrate some willingness to administer costly punishment as unequal behavior increases, (ii) the magnitude of this punishment varies substantially across populations, and (iii) costly punishment positively covaries with altruistic behavior across populations. These findings are consistent with models of the gene-culture coevolution of human altruism and further sharpen what any theory of human cooperation needs to explain.

Femtosecond resolution electron scattering techniques are applied to resolve the first atomic-scale steps following absorption of a photon in the prototypical hybrid perovskite methylammonium lead iodide. Following above-gap photoexcitation, we directly resolve the transfer of energy from hot carriers to the lattice by recording changes in the mean square atomic displacements on 10-ps time scales. Measurements of the time-dependent pair distribution function show an unexpected broadening of the iodine-iodine correlation function while preserving the Pb-I distance. This indicates the formation of a rotationally disordered halide octahedral structure developing on picosecond time scales. This work shows the important role of light-induced structural deformations within the inorganic sublattice in elucidating the unique optoelectronic functionality exhibited by hybrid perovskites and provides new understanding of hot carrier-lattice interactions, which fundamentally determine solar cel...

The odd-numbered carbon clusters C 119 , C,2 and C, 39 have been observed in the mass spectra of toluene extacts of fullerene soots and of the products of ozone-fullerene reactions. Specifically, ozone-C6o reactions yield C 119 , and ozone-Cm reactions yield C 139 , and ozone-(%/C7C) reactions produce C 119 , C , 29, and C 139 . These unexpected species correspond to dimers of Cý0, C6/C7, and C7o, respectively, less one carbon atom, and are stable gas-phase ions with behavior similar to that of fullerenes. The results suggest a new route to functionalization and derivatization of fullerenes through controlled ozone-catalyzed cage-opening reactions.

Despite its widespread use in nanocomposites, the effect of embedding graphene in highly viscoelastic polymer matrices is not well understood. We added graphene to a lightly cross-linked polysilicone, often encountered as Silly Putty, changing its electromechanical properties substantially. The resulting nanocomposites display unusual electromechanical behavior, such as postdeformation temporal relaxation of electrical resistance and nonmonotonic changes in resistivity with strain. These phenomena are associated with the mobility of the nanosheets in the low-viscosity polymer matrix. By considering both the connectivity and mobility of the nanosheets, we developed a quantitative model that completely describes the electromechanical properties. These nanocomposites are sensitive electromechanical sensors with gauge factors >500 that can measure pulse, blood pressure, and even the impact associated with the footsteps of a small spider.

Chong et al ., Nishio et al ., and Suri et al . (Reports, 24 March 2006, pp. 1774 , 1775 , and 1778 ) confirmed that treating nonobese diabetic (NOD) mice with an immune adjuvant and semisyngenic spleen cells can reverse the disease but found that spleen cells did not contribute to the observed recovery of pancreatic islets. We show that islet regeneration predominately originates from endogenous cells but that introduced spleen cells can also contribute to islet recovery.

SARS-CoV-2 across Africa The impact of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has been hard to track in African countries, largely because of patchy data. Wilkinson et al . curated viral genomes collected in 2021 from several countries across the continent. Outbreaks during 2020 in each African country were initiated by imported cases, mostly from Europe. As the pandemic developed, case numbers in African countries were likely many times higher than reported, and subsequent waves of the pandemic appear to have been more severe. Consequently, high-transmission variants have emerged that have spread within the continent, and African countries must be included in global control efforts. —CA

Assessing Singletons The one-child policy introduced by the government of China in 1979 increased the proportion of urban families with an only child; later referred to as "little emperors" in media reports. In 2010, Cameron et al. (p. 953 , published online 10 January) recruited approximately 400 residents of Beijing who had been born either before the implementation of the policy (1975 and 1978) or after (1980 and 1983). Using economic games to measure trust, risk, and willingness to compete, they found that the post-1979 cohorts were less trusting and less willing to compete and also more risk averse.