Tight Relation Research Articles

Systematic Investigation of Dust and Gaseous CO in 12 Nearby Molecular Clouds

We report on the first uniform and systematic study of dust and molecular gas in nearby molecular clouds. We use surveys of dust extinction and emission to determine the opacity and map the distribution of the dust within a dozen local clouds in order to derive a uniform set of basic cloud properties. We find (1) the average dust opacity 〈κ d,353〉 = 0.8 cm2 g−1 with variations of a factor of ∼2 between clouds, (2) cloud probability density functions are exquisitely described by steeply falling power laws with a narrow range of slope, and (3) a tight scaling relation for the cloud sample, indicative of a cloud population with an exactingly constant average surface density above a common fixed boundary. We compare these results to uniformly analyzed CO surveys. We measure the CO mass conversion factors and assess the efficacy of CO for tracing the physical properties of molecular clouds. We find 〈α CO〉 = 4.31 ± 0.67 M ⊙ (K km s−1 pc2)−1 (corresponding to X CO = 1.97 ×1020 cm−2(K km s−1)−1). We demonstrate that CO observations are a poor tracer of column density and structure on sub-cloud spatial scales. On cloud scales, CO observations can provide measurements consistent with those of the dust, provided data are analyzed in a similar, self-consistent fashion. Measurements of average giant molecular cloud surface density are sensitive to choice of cloud boundary. Care must be exercised to adopt common fixed boundaries when comparing surface densities for cloud populations within and between galaxies.

The Factory and the Beehive. IV. A Comprehensive Study of the Rotation X-Ray Activity Relation in Praesepe and the Hyades

X-ray observations of low-mass stars in open clusters are critical to understanding the dependence of magnetic activity on stellar properties and their evolution. Praesepe and the Hyades, two of the nearest, most-studied open clusters, are among the best available laboratories for examining the dependence of magnetic activity on rotation for stars with masses ≲1 M ⊙. We present an updated study of the rotation–X-ray activity relation in the two clusters. We updated membership catalogs that combine pre-Gaia catalogs with new catalogs based on Gaia Data Release 2. The resulting catalogs are the most inclusive ones for both clusters: 1739 Praesepe and 1315 Hyades stars. We collected X-ray detections for cluster members, for which we analyzed, re-analyzed, or collated data from ROSAT, the Chandra X-ray Observatory, the Neil Gehrels Swift Observatory, and XMM-Newton. We have detections for 326 Praesepe and 462 Hyades members, of which 273 and 164, respectively, have rotation periods—an increase of 6× relative to what was previously available. We find that at ≈700 Myr, only M dwarfs remain saturated in X-rays, with only tentative evidence for supersaturation. We also find a tight relation between the Rossby number and fractional X-ray luminosity L X/L bol in unsaturated single members, suggesting a power-law index between −3.2 and −3.9. Lastly, we find no difference in the coronal parameters between binary and single members. These results provide essential insight into the relative efficiency of magnetic heating of the stars’ atmospheres, thereby informing the development of robust age-rotation-activity relations.

Stellar masses, sizes, and radial profiles for 465 nearby early-type galaxies: An extension to theSpitzersurvey of stellar structure in Galaxies (S4G)

Context.TheSpitzerSurvey of Stellar Structure in Galaxies (S4G) is a detailed study of over 2300 nearby galaxies in the near-infrared (NIR), which has been critical to our understanding of the detailed structures of nearby galaxies. Because the sample galaxies were selected only using radio-derived velocities, however, the survey favored late-type disk galaxies over lenticulars and ellipticals.Aims.A follow-upSpitzersurvey was conducted to rectify this bias, adding 465 early-type galaxies (ETGs) to the original sample, to be analyzed in a manner consistent with the initial survey. We present the data release of this ETG extension, up to the third data processing pipeline (P3): surface photometry.Methods.We produce curves of growth and radial surface brightness profiles (with and without inclination corrections) using reduced and maskedSpitzerIRAC 3.6 μm and 4.5 μm images produced through Pipelines 1 and 2, respectively. From these profiles, we derive the following integrated quantities: total magnitudes, stellar masses, concentration parameters, and galaxy size metrics. We showcase NIR scaling relations for ETGs among these quantities.Results.We examine general trends across the whole S4G and ETG extension among our derived parameters, highlighting differences between ETGs and late-type galaxies (LTGs). The latter are, on average, more massive and more concentrated than LTGs, and subtle distinctions are seen among ETG morphological subtypes. We also derive the following scaling relations and compare them with previous results in visible light: mass-size (both half-light and isophotal), mass-concentration, mass-surface brightness (central, effective, and within 1 kpc), and mass-color.Conclusions.We find good agreement with previous works, though some relations (e.g., mass-central surface brightness) will require more careful multicomponent decompositions to be fully understood. The relations between mass and isophotal radius and between mass and surface brightness within 1 kpc, in particular, show notably small scatter. The former provides important constraints on the limits of size growth in galaxies, possibly related to star formation thresholds, while the latter–particularly when paired with the similarly tight relation for LTGs–showcases the striking self-similarity of galaxy cores, suggesting they evolve little over cosmic time. All of the profiles and parameters described in this paper will be provided to the community via the NASA/IPAC database on a dedicated website.

A tight relation between series-parallel graphs and bipartite distance hereditary graphs

Bandelt and Mulder’s structural characterization of bipartite distance hereditary graphs asserts that such graphs can be built inductively starting from a single vertex and by repeatedly adding either pendant vertices or twins (i.e., vertices with the same neighborhood as an existing one). Dirac and Duffin’s structural characterization of 2–connected series–parallel graphs asserts that such graphs can be built inductively starting from a single edge by adding either edges in series or in parallel. In this paper we give an elementary proof that the two constructions are the same construction when bipartite graphs are viewed as the fundamental graphs of a graphic matroid. We then apply the result to re-prove known results concerning bipartite distance hereditary graphs and series–parallel graphs and to provide a new class of polynomially-solvable instances for the integer multi-commodity flow of maximum value.

Coherence, path predictability, and I concurrence: A triality

It is well known that fringe contrast is not a good quantifier of the wave nature of a quanton in multipath interference. A new interference visibility, based on the Hilbert-Schmidt coherence is introduced. It is demonstrated that this visibility is a good quantifier of wave nature, and can be experimentally measured. A generalized path predictability is introduced, which reduces to the predictability of Greenberger and Yasin, for the case of two paths. In a multipath, which-way interference experiment, the new visibility, the predictability and the I-concurrence (quantifying the entanglement between the quanton and the path-detector), are shown to follow a tight triality relation. It quantifies the essential role that entanglement plays in multipath quantum complementarity, for the first time.

MIGHTEE-H i: the H i size–mass relation over the last billion years

ABSTRACT We present the observed H i size–mass relation of 204 galaxies from the MIGHTEE Survey Early Science data. The high sensitivity of MeerKAT allows us to detect galaxies spanning more than 4 orders of magnitude in H i mass, ranging from dwarf galaxies to massive spirals, and including all morphological types. This is the first time the relation has been explored on a blind homogeneous data set that extends over a previously unexplored redshift range of 0 < z < 0.084, i.e. a period of around one billion years in cosmic time. The sample follows the same tight logarithmic relation derived from previous work, between the diameter ($D_{\rm H\, \small {\rm I}}$) and the mass ($M_{\rm H\, \small {\rm I}}$) of H i discs. We measure a slope of 0.501 ± 0.008, an intercept of $-3.252^{+0.073}_{-0.074}$, and an observed scatter of 0.057 dex. For the first time, we quantify the intrinsic scatter of 0.054 ± 0.003 dex (${\sim } 10 {{\ \rm per\ cent}}$), which provides a constraint for cosmological simulations of galaxy formation and evolution. We derive the relation as a function of galaxy type and find that their intrinsic scatters and slopes are consistent within the errors. We also calculate the $D_{\rm H\, \small {\rm I}}{ \!-\! }M_{\rm H\, \small {\rm I}}$ relation for two redshift bins and do not find any evidence for evolution with redshift. These results suggest that over a period of one billion years in look-back time, galaxy discs have not undergone significant evolution in their gas distribution and mean surface mass density, indicating a lack of dependence on both morphological type and redshift.

Natural killer cell-related gene signature predicts malignancy of glioma and the survival of patients

BackgroundNatural killer (NK) cells-based therapies are one of the most promising strategies against cancer. The aim of this study is to investigate the natural killer cell related genes and its prognostic value in glioma.MethodsThe Chinese Glioma Genome Atlas (CGGA) was used to develop the natural killer cell-related signature. Risk score was built by multivariate Cox proportional hazards model. A cohort of 326 glioma samples with whole transcriptome expression data from the CGGA database was included for discovery. The Cancer Genome Atlas (TCGA) datasets was used for validation. GO and KEGG were used to reveal the biological process and function associated with the natural killer cell-related signature. We also collected the clinical pathological features of patients with gliomas to analyze the association with tumor malignancy and patients’ survival.ResultsWe screened for NK-related genes to build a prognostic signature, and identified the risk score based on the signature. We found that NK-related risk score was independent of various clinical factors. Nature-killer cell gene expression is correlated with clinicopathological features of gliomas. Innovatively, we demonstrated the tight relation between the risk score and immune checkpoints, and found NK-related risk score combined with PD1/PDL1 patients could predict the patient outcome.ConclusionNatural killer cell-related gene signature can predict malignancy of glioma and the survival of patients, these results might provide new view for the research of glioma malignancy and individual immunotherapy.

Interplay of tactile and motor information in constructing spatial self-perception

During active movement, there is normally a tight relation between motor command and sensory representation about the resulting spatial displacement of the body. Indeed, some theories of space perception emphasize the topographic layout of sensory receptor surfaces, while others emphasize implicit spatial information provided by the intensity of motor command signals. To identify which has the primary role in spatial perception, we developed experiments based on everyday self-touch, in which the right hand strokes the left arm. We used a robot-mediated form of self-touch to decouple the spatial extent of active or passive right hand movements from their tactile consequences. Participants made active movements of the right hand between unpredictable, haptically defined start and stop positions, or the hand was passively moved between the same positions. These movements caused a stroking tactile motion by a brush along the left forearm, with minimal delay, but with an unpredictable spatial gain factor. Participants judged the spatial extent of either the right hand's movement, or of the resulting tactile stimulation to their left forearm. Across five experiments, we found that movement extent strongly interfered with tactile extent perception, and vice versa. Crucially, interference in both directions was stronger during active than passive movements. Thus, voluntary motor commands produced stronger integration of multiple sensorimotor signals underpinning the perception of personal space. Our results prompt a reappraisal of classical theories that reduce space perception to motor command information.

The effect of background speech on attentive sound processing: A pupil dilation study

Listening to task-irrelevant speech while performing a cognitive task can involuntarily deviate our attention and lead to decreases in performance. One explanation for the impairing effect of irrelevant speech is that semantic processing can consume attentional resources. In the present study, we tested this assumption by measuring performance in a non-linguistic attentional task while participants were exposed to meaningful (native) and non-meaningful (foreign) speech. Moreover, based on the tight relation between pupillometry and attentional processes, we also registered changes in pupil diameter size to quantify the effect of meaningfulness upon attentional allocation. To these aims, we recruited 41 native German speakers who had neither received formal instruction in French nor had extensive informal contact with this language. The focal task consisted of an auditory oddball task. Participants performed a duration discrimination task containing frequently repeated standard sounds and rarely presented deviant sounds while a story was read in German or (non-meaningful) French in the background. Our results revealed that, whereas effects of language meaningfulness on attention were not detectable at the behavioural level, participants' pupil dilated more in response to the sounds of the auditory task when background speech was played in non-meaningful French compared to German, independent of sound type. In line with the initial hypothesis, this suggested that semantic processing of the native language required attentional resources, which lead to fewer resources devoted to the processing of the sounds of the focal task. Our results highlight the potential of the pupil dilation response for the investigation of subtle cognitive processes that might not surface when only behaviour is measured.

Cultural Intervention in the Spanish Civil War: A Comparative Analysis of Nazi and Fascist Propaganda

This article analyses Fascist and Nazi propaganda during the Spanish Civil War, asking how both nations exploited the conflict and how they interacted with each other and the emerging Francoist state. In so doing, the article highlights the propagandistic value of Nazi-fascist cultural policy and sheds light on the development of the Nazi-fascist alliance. It shows how despite Italy being in many ways at the forefront of the intervention, the development of tight Nazi-falangist relations, among other factors, led to the replacement of Fascist Italy by Nazi Germany as a model for the rebirth of the nation in Spain. This, in turn, sheds light on the Nazi-fascist Alliance, showing how Italy's wide-ranging propaganda originated from a place of self-perceived weakness rather than strength. German–Italian relations were marked by a complex and non-linear dynamic of admiration and jealousy, collaboration and competition, which made itself evident in the Spanish conflict and beyond.

Probing the radial acceleration relation and the strong equivalence principle with the Coma cluster ultra-diffuse galaxies

The tight radial acceleration relation (RAR) obeyed by rotationally supported disk galaxies is one of the most successful a priori predictions of the modified Newtonian dynamics (MOND) paradigm on galaxy scales. Another important consequence of MOND as a classical modification of gravity is that the strong equivalence principle (SEP) – which requires the dynamics of a small, free-falling, self-gravitating system not to depend on the external gravitational field in which it is embedded – should be broken. Multiple tentative detections of this so-called external field effect (EFE) of MOND have been made in the past, but the systems that should be most sensitive to it are galaxies with low internal gravitational accelerations residing in galaxy clusters within a strong external field. Here, we show that ultra-diffuse galaxies (UDGs) in the Coma cluster do lie on the RAR, and that their velocity dispersion profiles are in full agreement with isolated MOND predictions, especially when including some degree of radial anisotropy. However, including a breaking of the SEP via the EFE seriously deteriorates this agreement. We discuss various possibilities to explain this within the context of MOND, including a combination of tidal heating and higher baryonic masses. We also speculate that our results could mean that the EFE is screened in cluster UDGs. The fact that this would happen precisely within galaxy clusters, where classical MOND fails, could be especially relevant to the nature of the residual MOND missing mass in clusters of galaxies.

Emerging Roles of Microfluidics in Brain Research: From Cerebral Fluids Manipulation to Brain-on-a-Chip and Neuroelectronic Devices Engineering.

Remarkable progress made in the past few decades in brain research enables the manipulation of neuronal activity in single neurons and neural circuits and thus allows the decipherment of relations between nervous systems and behavior. The discovery of glymphatic and lymphatic systems in the brain and the recently unveiled tight relations between the gastrointestinal (GI) tract and the central nervous system (CNS) further revolutionize our understanding of brain structures and functions. Fundamental questions about how neurons conduct two-way communications with the gut to establish the gut-brain axis (GBA) and interact with essential brain components such as glial cells and blood vessels to regulate cerebral blood flow (CBF) and cerebrospinal fluid (CSF) in health and disease, however, remain. Microfluidics with unparalleled advantages in the control of fluids at microscale has emerged recently as an effective approach to address these critical questions in brain research. The dynamics of cerebral fluids (i.e., blood and CSF) and novel in vitro brain-on-a-chip models and microfluidic-integrated multifunctional neuroelectronic devices, for example, have been investigated. This review starts with a critical discussion of the current understanding of several key topics in brain research such as neurovascular coupling (NVC), glymphatic pathway, and GBA and then interrogates a wide range of microfluidic-based approaches that have been developed or can be improved to advance our fundamental understanding of brain functions. Last, emerging technologies for structuring microfluidic devices and their implications and future directions in brain research are discussed.

Machining subsurface deformation under various rake angles

Subsurface plastic deformation has attracted a great deal of attention due to its tight relation with surface hardening, microstructure alteration, grain refinement, and white layer formation. Therefore, it is critical to study the subsurface plastic deformation during the machining process. In this study, the digital image correlation technique (DIC) is used to measure the subsurface deformation during the orthogonal cutting process. The cutting tool’s rake angle is varied by a specially designed experimental setup. FEM simulations are carried out to predict the subsurface deformation and comparisons with the experimental measurements are conducted. This study can deepen the understanding of the generation of surface integrity and can be further developed for implementation into the online conditioning of surface integrity.

Practical Research on Physical Problem Solving with Mathematical Graphical Models

There is the tightest relation between mathematics and physics among all disciplines. Specifically, mathematics can serve as an instrument to describe physical phenomena, while physical theory can be used to interpret mathematical laws. As a basic discipline of all natural disciplines, mathematics can provide operational tools, thinking methods, and process simplification approaches for the proposal and development of physical problems. The mathematical graphical model can effectively improve the efficiency of problem solving. This study is conducted based on the transfer theory. Besides, the methods and practice of physical problem solving with mathematical graphical models are analyzed from the perspective of specific examples in physics.

New insights into the criterion of fast radio burst in the light of FRB 20121102A

The total number of observed fast radio burst (FRB) events is rising rapidly thanks to the improvement of existing radio telescopes and the delivery of new facilities. In particular, the Five-hundred-meter Aperture Spherical radio Telescope Collaboration recently reported more than one thousand bursts in a short observing period of 47 days. The striking bimodal distribution in their work motivated us to revisit the definition of FRBs. In this work, we ascribe the bimodal distribution to two physical kinds of radio bursts that may exhibit different radiation mechanisms. We propose using brightness temperature to separate two subtypes. For FRB 20121102A, the critical brightness temperature is TB, cri ≃ 1033 K. Bursts with TB ≥ TB, cri are denoted as “classical” FRBs and we find a tight pulse width-fluence relation (T ∝ ℱν0.306) for them. On the contrary, the other bursts are considered as “atypical” bursts that may have originated from a different type of physical process. We suggest that for each FRB event, a similar dividing line should exist but that the TB, cri is not necessarily the same in such cases. Its exact value depends on the FRB radiation mechanism and the properties of the source.

Hybrid Model Predictive Control for Hybrid Electric Vehicle Energy Management Using an Efficient Mixed-Integer Formulation

This paper proposes to use hybrid model predictive control (HMPC) for energy management in hybrid electric vehicle (HEV) using an efficient formulation. HEV has two sources of energy - electric motor and internal combustion engine (ICE) - allowing it an additional degree of freedom to optimize the ratio between the use of two energy sources. HEV energy management is crucial to exploit its potential to reduce fuel consumption and emissions. However, it is challenging to achieve the optimal solution along with the fast dynamics of HEVs. In this paper, instead of using a nonlinear, computationally expensive dynamic model of HEV, a piecewise afne (PWA) model is used to depict its behavior, implemented with multiple linear regression. The validation of the developed model is taken with standard drive cycles. Based on the PWA model, an optimal control problem of HMPC was formulated as mixed integer linear programming (MILP). Conventionally, mixed logical dynamical (MLD) system has been used in the process control field, including early studies of HEV control. This paper applies Big-M formulation which is efficient in its problem size and tight inequality relation for integer variables. The performance of the HMPC controller was examined in a simulated environment based on MATLAB/Simulink HEVP2 application. As a result, HMPC shows superior control performance than the equivalent consumption minimization strategy (ECMS).

Ab initiononadiabatic dynamics of semiconductor materials via surface hopping method

Photoinduced carrier dynamic processes are without doubt the main driving force responsible for the efficient performance of semiconductor nano-materials in applications like photoconversion and photonics. Nevertheless, establishing theoretical insights into these processes is computationally challenging owing to the multiple factors involved in the processes, namely reaction rate, material surface area, material composition etc. Modelling of photoinduced carrier dynamic processes can be performed via nonadiabatic molecular dynamics (NA-MD) methods, which are methods specifically designed to solve the time-dependent Schrodinger equation with the inclusion of nonadiabatic couplings. Among NA-MD methods, surface hopping methods have been proven to be a mighty tool to mimic the competitive nonadiabatic processes in semiconductor nanomaterials, a worth noticing feature is its exceptional balance between accuracy and computational cost. Consequently, surface hopping is the method of choice for modelling ultrafast dynamics and more complex phenomena like charge separation in Janus transition metal dichalcogenides-based van der Waals heterojunction materials. Covering latest state-of-the-art numerical simulations along with experimental results in the field, this review aims to provide a basic understanding of the tight relation between semiconductor nanomaterials and the proper simulation of their properties via surface hopping methods. Special stress is put on emerging state-ot-the-art techniques. By highlighting the challenge imposed by new materials, we depict emerging creative approaches, including high-level electronic structure methods and NA-MD methods to model nonadiabatic systems with high complexity.

A first estimate of the Milky Way dark matter halo spin

The spin, or normalized angular momentumλ, of dark matter halos in cosmological simulations follows a log normal distribution and has little correlation with galaxy observables such as stellar masses or sizes. There is currently no way to infer theλparameter of individual halos hosting observed galaxies. Here, we present a first attempt to measureλstarting from the dynamically distinct disks and stellar halos identified in high-resolution cosmological simulations with theGalactic Structure Finder (gsf). In a subsample of NIHAO galaxies analyzed withgsf, we find tight correlations between the total angular momentum of the dark matter halos,Jh, and the azimuthal angular momentum,Jz, of the dynamical distinct stellar components of the form: log(Jh) =α+β⋅log(Jz). The stellar halos have the tightest relation withα = 9.50 ± 0.42 andβ = 0.46 ± 0.04. The other tight relation is with the disks, for whichα = 6.15 ± 0.92 andβ = 0.68 ± 0.07. While the angular momentum is difficult to estimate for stellar halos, there are various studies that calculatedJzfor disks. In application to the observations, we usedGaiaDR2 and APOGEE data to generate a combined kinematics-abundance space, where the Galaxy’s thin and thick stellar disks stars can be neatly separated and their rotational velocity profiles,vϕ(R), can be computed. For both disks,vϕ(R) decreases with radius with ∼2 km s−1kpc−1forR ≳ 5 kpc, resulting in velocities ofvϕ,thin= 221.2 ± 0.8 km s−1andvϕ,thick= 188 ± 3.4 km s−1at the solar radius. We use our derivedvϕ,thin(R) andvϕ,thick(R) together with the mass model for the Galaxy of Cautun et al. (2020, MNRAS, 494, 4291) to compute the angular momentum for the two disks:Jz, thin = (3.26 ± 0.43)×1013andJz, thick = (1.20 ± 0.30)×1013 M⊙kpc km s−1, where the dark halo is assumed to follow a contracted NFW profile. Adopting the correlation found in simulations, the total angular momentum of the Galaxy’s dark halo is estimated to beJh= 2.69−0.32+0.371015 M⊙kpc km s−1and the spin estimate isλMW= 0.061−0.016+0.022, which translates into a probability of 21% using the universal log normal distribution function ofλ. If the Galaxy’s dark halo is assumed to follow a NFW profile instead, the spin becomesλMW= 0.088−0.020+0.024, making the Milky Way a more extreme outlier (with a probability of only 0.2%).

A Flute, Musical Bows and Bamboo Clarinets that "Speak" in the Amazon Rainforest; Speech and Music in the Gavião Language of Rondônia.

The Gavião, a native Amazonian group in Rondônia, Brazil, use three different traditional musical instruments that they identify as “speaking” ones and that are characterized by a very tight music-lyric relation through similar pitch patterns: a flute (called kotiráp), a pair of mouth bows (iridináp), and three large bamboo clarinets (totoráp), played by three different players, each one playing a single-note clarinet. They show in different ways the relation of acoustic iconicity which exists between the words of the songs’ lyrics and the music played on such instruments to “sing” the songs. Linguistic analysis makes it possible to understand the phonetic and phonological nature of the iconicity. The sung speech form, being intermediate between the spoken and the instrumental forms, is useful for both learning and explaining the musical notes. In a language with distinctive tone and length, such as Gavião of Rondônia, the first question about speech that is played by musical instruments is the relation between the melodies and the supersegmental phonology of the corresponding words in sung speech and in modal spoken speech. It is influenced by the phonological possibilities of the spoken form and by the musical possibilities of the instrumental form. The description and analysis of Gavião instrumental speech and song practices are found to be a noteworthy contribution to the typology of instrumental language surrogates associated with a tone language, one that calls for a reexamination of hypotheses about which aspects of the phonological/phonetic structure can be transposed in instrumental speech and how this can be done. The role of this kind of instrumental sung speech is artistic and also practical as it contributes to maintain the oral heritage. Such practice represents a little-studied and threatened cultural heritage of the traditional substratum of the cultures of Amazonia.

Subwavelength generation of orientation-unlimited energy flow in 4π microscopy.

Manipulation of light energy flow within the tight focus not only is important to the fundamental study of light-matter interactions but also underpins significant practical applications. However, the coupling between the electric and the magnetic fields of a focused light beam sets a fundamental barrier for independent control of these field components, restricting the focal energy flow primarily in the axial direction. In this paper, a 4π microscopic configuration is theoretically proposed to untangle the tight relation between the electric field and the magnetic field in a subwavelength-scale focal voxel. By independently altering the amplitudes of different field components in the focal region, energy flow with three-dimensionally unlimited orientation and ultra-high orientation purity (more than 90%) can be generated. This result expands the flexibility of energy flow manipulations and holds great potential in nanophotonics such as light scattering and optical force at subwavelength dimensions.