Greater sensitivity of the cortical face processing system to perceptually-equated face detection

Face detection, the perceptual capacity to identify a visual stimulus as a face before probing deeper into specific attributes (such as its identity or emotion), is essential for social functioning. Despite the importance of this functional capacity, face detection and its underlying brain mechanisms are not well understood. This study evaluated the roles that the cortical face processing system, which is identified largely through studying other aspects of face perception, play in face detection. Specifically, we used functional magnetic resonance imaging (fMRI) to examine the activations of the fusifom face area (FFA), occipital face area (OFA) and superior temporal sulcus (STS) when face detection was isolated from other aspects of face perception and when face detection was perceptually-equated across individual human participants (n=20). During face detection, FFA and OFA were significantly activated, even for stimuli presented at perceptual-threshold levels, whereas STS was not. During tree detection, however, FFA and OFA were responsive only for highly salient (i.e., high contrast) stimuli. Moreover, activation of FFA during face detection predicted a significant portion of the perceptual performance levels that were determined psychophysically for each participant. This pattern of result indicates that FFA and OFA have a greater sensitivity to face detection signals and selectively support the initial process of face vs. non-face object perception.

The effects of bortezomib alone or in combination with 5-fluorouracil on proliferation and apoptosis of choriocarcinoma cells

PURPOSE

To investigate the effects of bortezomib alone and in combination with 5-fluorouracil (5-FU) on proliferation and apoptosis in the human choriocarcinoma cell line JEG-3.

MATERIALS AND METHODS

Cells were treated with bortezomib, 5-FU or with a combination. Proliferation and apoptosis were measured. NF-iB protein expression was examined using immunofluorescence.

RESULTS

Following treatment with ten nM bortezomib, rates of apoptosis were significantly higher than controls (p < 0.05) and NF-kB expression increased. 5-FU at 0.025 μg/ml or 0.25 μg/ml resulted in 60.1 ± 0.4% and 67.0 ± 0.2% growth inhibition, respectively, an increase compared to individual treatment (p < 0.05). Apoptosis in cells treated with bortezomib +5-FU was significantly higher than either treatment alone (p < 0.05). Inhibition of proliferation by the combination treatment was synergistic.

CONCLUSION

Bortezomib alone or in combination with 5-FU inhibited JEG-3 cell proliferation and induced apoptosis by increasing NF-kB expression. Combination treatment exerted synergistic effects on growth inhibition.

Sciatic-femoral nerve block versus unilateral spinal anesthesia for outpatient knee arthroscopy: a meta-analysis

BACKGROUND

Because of the short hospital stay involved in outpatient knee arthroscopy, anesthesiologists should provide an effective and safe anesthesia scheme. Unilateral spinal anesthesia is a conventional choice for outpatient knee arthroscopy, and combined sciatic-femoral nerve block also permits successful results. This study aimed to compare sciatic-femoral nerve block with unilateral spinal anesthesia for outpatient knee arthroscopy.

METHODS

We screened randomized controlled trials (RCTs) that compared sciatic-femoral nerve block (SFB) with unilateral spinal anesthesia (USA) from EMBASE, MEDLINE and the Cochrane Library. Ten statistic parameters, such as time-to-readiness for discharge (TRD, minutes), time to first spontaneous urination (minutes), time to perform (PT, minutes), Visual Analogue Scale (VAS) for postoperative (24 hours) pain, patients' satisfaction, and total anesthesia time (TAT, minutes) were considered in this study. RevMan 5.2 and Stata 12.0 softwares were used for data analysis.

RESULT

There were 7 RCTs including 402 total patients which met our criteria. Compared with the USA group, in the SFB group TRD (mean difference [MD]=-38.8; 95% CI [-63.7, -14.0]; P=0.002) and time to first spontaneous urination (MD=-78.2; 95% CI [-92.7, -63.7]; P<0.00001) were shorter, TAT (MD=100.2; 95% CI [30.3, 170.1]; P=0.005) and PT (MD=4.0; 95% CI [2.4, 5.6]; P<0.00001; I2=97%) were longer in the SFB group. For the two groups, no statistically significant differences were observed in patients' satisfaction (MD=3.2; 95% CI [0.3, 31.8]; P=0.33).

CONCLUSION

SFB provided faster bladder function recovery and faster discharging from hospital, hence it could be a good alternative to USA for outpatient knee arthroscopy.

Optimal blood pressure levels in patients undergoing intravenous thrombolysis for AIS

AIM

We wished to define the most optimal blood pressure ranges in patients with acute ischemic stroke (AIS) undergoing intravenous thrombolysis treatment.

METHODS

The study comprised 626 patients with AIS who underwent the treatment with recombinant tissue plasminogen activator. The patients were randomly assigned to receive either conservative blood pressure lowering regimen (N.=302, target systolic blood pressure of 151-185 mmHg) or intensive blood pressure lowering regimen (N.=324, target systolic blood pressure of 141-150 mm Hg). The outcomes were occurrence of intracranial hemorrhages and survival after 3 months post-treatment.

RESULTS

Patients who received intensive blood pressure lowering regimen showed significantly lower rates of intracranial hemorrhage and mortality. Also, these patients demonstrated a trend to better overall condition.

CONCLUSION

Intensive blood pressure lowering regimen warrants a safe and effective intravenous thrombolysis in patients with AIS, and the targeted systolic blood pressure levels should be within 141-150 mmHg.

Large-scale two-dimensional MoS₂ photodetectors by magnetron sputtering

We report on the demonstration of photodetectors based on large scale two-dimensional molybdenum disulfide (MoS2) transition metal dichalcogenides. Excellent film uniformity and precise control of the MoS2 thickness down to a monolayer (~0.75nm) were achieved by magnetron sputtering synthesis approach. In particular, the photodetectors integrated with five MoS2 monolayers exhibit a high photoresponsivity of 1.8 A/W, an external quantum efficiency exceeding 260%, and a photodetectivity of ~5 x 10(8) Jones for a wavelength of 850 nm, surpassing the performance of mechanically exfoliated based photodetectors.

Effects of p-chlorophenoxyisobutyric acid, arabinogalactan, and activated charcoal on microspore embryogenesis in kale

To improve embryogenesis in microspore cultures of kale (Brassica oleracea L. var. acephala DC.), 6-benzylaminopurine (6-BA), naphthaleneacetic acid (NAA), arabinogalactan (AG), p-chlorophenoxyisobutyric acid (PCIB), and activated charcoal (AC) were added to the medium using four varieties of kale. The results showed that the addition of AG (0.1-0.2 g/L), AC (0.1-0.2 g/L) or a combination of 6-BA (0.1-0.2 mg/L) and NAA (0.1-0.2 mg/L) promoted embryo-genesis. Adding 40 μM PCIB or a combination of 40 μM PCIB and 0.2 g/L AC to NLN-13 medium at pH 5.8 effectively enhanced embryogenesis. Treatment with a combination of 40 μM PCIB and 10 mg/L AG gave the highest rate of embryonic induction, especially in genotype "Y007," which showed a twelve-fold increase in yield.

Serum immunoglobulin E level and its impact on the pregnancy outcome associated with fetal growth restriction: a prospective cohort study

We evaluated the relationship between total serum immunoglobulin E (IgE) levels and pregnancy outcome in a prospective cohort study focusing on fetal growth restriction (FGR). Sixty women with FGR and twenty with normal singleton pregnancy were enrolled during their third trimester. Infants were followed up for 6 months. Blood samples were obtained from pregnant women during the third trimester; cord blood samples were also taken. Six months after birth, blood samples were obtained from infants. Demographic and baseline characteristics were compared between groups. Birth weight, length and head circumference of neonates in the FGR group were lower than those in the control group. Total serum IgE level was significantly increased in third-trimester pregnant women with FGR compared with normal group (P < 0.05). However, this trend was not observed in the cord blood at birth or peripheral blood of 6-month-old infants. The prevalence of atopic eczema between the 2 groups was similar. Linear regression analysis revealed that the IgE level in the third trimester was negatively correlated with birth weight (P < 0.05). Higher serum IgE level in the cord blood was significantly associated with an increased risk of being small for gestational age (P < 0.05). In conclusion, IgE levels in the third trimester of pregnancy and cord blood are strongly related to birth outcomes of FGR.

Orthotopic models of pediatric brain tumors in zebrafish

High-throughput screens (HTS) of compound toxicity against cancer cells can identify thousands of potential new drug-leads. But only limited numbers of these compounds can progress to expensive and labor-intensive efficacy studies in mice, creating a 'bottle neck' in the drug development pipeline. Approaches that triage drug-leads for further study are greatly needed. Here we provide an intermediary platform between HTS and mice by adapting mouse models of pediatric brain tumors to grow as orthotopic xenografts in the brains of zebrafish. Freshly isolated mouse ependymoma, glioma and choroid plexus carcinoma cells expressing red fluorescence protein were conditioned to grow at 34 °C. Conditioned tumor cells were then transplanted orthotopically into the brains of zebrafish acclimatized to ambient temperatures of 34 °C. Live in vivo fluorescence imaging identified robust, quantifiable and reproducible brain tumor growth as well as spinal metastasis in zebrafish. All tumor xenografts in zebrafish retained the histological characteristics of the corresponding parent mouse tumor and efficiently recruited fish endothelial cells to form a tumor vasculature. Finally, by treating zebrafish harboring ERBB2-driven gliomas with an appropriate cytotoxic chemotherapy (5-fluorouracil) or tyrosine kinase inhibitor (erlotinib), we show that these models can effectively assess drug efficacy. Our data demonstrate, for the first time, that mouse brain tumors can grow orthotopically in fish and serve as a platform to study drug efficacy. As large cohorts of brain tumor-bearing zebrafish can be generated rapidly and inexpensively, these models may serve as a powerful tool to triage drug-leads from HTS for formal efficacy testing in mice.

Persistent homology for the quantitative prediction of fullerene stability

Persistent homology is a relatively new tool often used for qualitative analysis of intrinsic topological features in images and data originated from scientific and engineering applications. In this article, we report novel quantitative predictions of the energy and stability of fullerene molecules, the very first attempt in using persistent homology in this context. The ground-state structures of a series of small fullerene molecules are first investigated with the standard Vietoris-Rips complex. We decipher all the barcodes, including both short-lived local bars and long-lived global bars arising from topological invariants, and associate them with fullerene structural details. Using accumulated bar lengths, we build quantitative models to correlate local and global Betti-2 bars, respectively with the heat of formation and total curvature energies of fullerenes. It is found that the heat of formation energy is related to the local hexagonal cavities of small fullerenes, while the total curvature energies of fullerene isomers are associated with their sphericities, which are measured by the lengths of their long-lived Betti-2 bars. Excellent correlation coefficients (>0.94) between persistent homology predictions and those of quantum or curvature analysis have been observed. A correlation matrix based filtration is introduced to further verify our findings.

Acarbose monotherapy and weight loss in Eastern and Western populations with hyperglycaemia: an ethnicity-specific meta-analysis

OBJECTIVE

To demonstrate if weight loss achieved with acarbose in individuals with hyperglycaemia differs between Eastern and Western populations.

METHODS

Databases and reference lists of clinical trials on acarbose were searched. Eligible studies were randomised controlled trials of acarbose monotherapy in populations with hyperglycaemia of more than 12-week duration that provided data on body weight (BW) or body mass index (BMI).

RESULTS

A total of 34 trials (6082 participants) were included. The effect of acarbose on BW was superior to that of placebo [weighted mean difference (WMD) = -0.52, 95% confidence interval (CI) -0.78 to -0.25], nateglinide (WMD = -1.33, 95% CI -1.51 to -0.75) and metformin (WMD = -0.67, 95% CI -1.14 to -0.20). Compared with placebo, there was a significantly greater weight loss of 0.92 kg (p < 0.05, I(2)  = 88.8%) with acarbose in Eastern populations (WMD = -1.20, 95% CI -1.51 to -0.75) than that in Western populations (WMD = -0.28, 95% CI -0.59 to 0.03). Across all studies, the acarbose group achieved a significantly larger absolute weight loss of (change from baseline) 1.35 kg (p < 0.05, I(2)  = 94.3%) in Eastern populations (WMD = -2.26, 95% CI -2.70 to -1.81) than in Western populations (WMD = -0.91, 95% CI -1.36 to -0.47). Nevertheless, the possible risk of bias in Eastern studies may influence the results.

CONCLUSION

The effect of acarbose on weight loss seems to be more pronounced in Eastern than in Western populations with hyperglycaemia, and is superior to that of placebo, nateglinide and metformin across both ethnicities.

Gene signatures of drug resistance predict patient survival in colorectal cancer

Different combinations of 5-fluorouracil (5-FU), oxaliplatin, irinotecan and other newly developed agents have been used to treat colorectal cancer. Despite the advent of new treatment regimens, the 5-year survival rate for metastatic colorectal cancer remains low (~10%). Knowing the drug sensitivity of a given tumor for a particular agent could significantly impact decision making and treatment planning. Biomarkers are proven to be successful in characterizing patients into different response groups. Using survival prediction analysis, we have identified three independent gene signatures, which are associated with sensitivity of colorectal cancer cells to 5-FU, oxaliplatin or irinotecan. On the basis of the three gene signatures, three score systems were developed to stratify patients from sensitive to resistance. These score systems exhibited robustness in stratify patients in two independent clinical studies. Patients with high scores in all three drugs exhibited the lowest survival.

Frame Field Singularity Correction for Automatic Hexahedralization

We present an automatic hexahedralization tool, based on a systematic treatment that removes some of the singularities that would lead to degenerate volumetric parameterization. Such singularities could be abundant in automatically generated frame fields guiding the interior and boundary layouts of the hexahedra in an all hexahedral mesh. We first give the mathematical definitions of the inadmissible singularities prevalent in frame fields, including newly introduced surface singularity types. We then give a practical framework for adjusting singularity graphs by automatically modifying the rotational transition of frames between charts (cells of a tetrahedral mesh for the volume) to resolve the issues detected in the internal and boundary singularity graph. After applying an additional re-smoothing of the frame field with the modified transition conditions, we cut the volume into a topologically trivial domain, with the original topology encoded by the self-intersections of the boundary of the domain, and solve a mixed integer problem on this domain for a global parameterization. Finally, a properly connected hexahedral mesh is constructed from the integer isosurfaces of (u,v,w) in the parameterization. We demonstrate the applicability of the method on complex shapes, and discuss its limitations.

The MTMR9 rs2293855 polymorphism is associated with glucose tolerance, insulin secretion, insulin sensitivity and increased risk of prediabetes

BACKGROUND

Polymorphism of rs2293855 in gene MTMR9 has been associated with obesity and metabolic syndrome. We aim to study the association of rs2293855 with type 2 diabetes mellitus (T2DM) intermediate phenotypes in a Han Chinese population.

METHODS

The polymorphism was genotyped in 838 Han Chinese individuals using Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS); all participants underwent a 75 g oral glucose tolerance test (OGTT); associations between the polymorphism and glucose tolerance, indices of insulin secretion and indices of insulin sensitivity were analyzed.

RESULTS

The frequency of genotypes and alleles differed significantly between normal glucose tolerance and prediabetes (P=0.043 and P=0.009, respectively). The GG homozygous presented higher fasting plasma glucose (P=0.009), higher 2-hour plasma glucose (P=0.024) and higher glucose area under the curve (AUC, P=0.01). Moreover, the G allele of rs2293855 was associated with glucose intolerance (fasting glucose, P=0.012; glucose AUC, P=0.006; 2-h glucose, P=0.024); it is also associated with decreased indices of insulin sensitivity (fasting insulin, P=0.043; insulin sensitivity index composite, P=0.009; homeostasis model assessment of insulin resistance, HOMA-IR, P=0.008) and decreased indices of insulin secretion (HOMA of beta cell function, HOMA-B, P=0.028; insulinogenic index, P=0.003). In addition, the minor allele G was also associated with increased risk of prediabetes (OR=1.463, 95%CI: 1.066-2.009, P=0.018).

CONCLUSIONS

Polymorphism of rs2293855 in MTMR9 is associated with measures of glucose tolerance, indices of insulin secretion and indices of insulin sensitivity. We also suggest that allele G is likely to increase the risk of prediabetes by influencing both insulin secretion and insulin sensitivity.

Huwe1 as a therapeutic target for neural injury

The ubiquitin-proteasome system (UPS) regulates many cellular processes, including protein stability, cell cycle control, DNA repair, transcription, signal transduction, and protein trafficking. In fact, UPS plays a key role in various stress conditions such as ischemia, glutamate toxicity, Alzheimer's disease, and Parkinson's disease. Huwe1, a homologous to E6-AP carboxy terminus (HECT) domain ubiquitin ligase, is now being regarded as a vital protein involved in neural stem cell differentiation, adult neurogenesis, and the DNA damage response pathway. In response to DNA damage, Huwe1 may have a dual function in arresting DNA replication and in ending checkpoint signaling. The proliferation and differentiation of neural stem cells regulated by Huwe1-mediated Notch signaling could also play an important role in neural protection following neural injury. Considering Huwe1 is required for neural precursor survival and the regulation of the DNA damage response pathway, there is growing evidence and considerable hope that Huwe1 might be a therapeutic target for neural injury.

FaceWarehouse: a 3D facial expression database for visual computing

We present FaceWarehouse, a database of 3D facial expressions for visual computing applications. We use Kinect, an off-the-shelf RGBD camera, to capture 150 individuals aged 7-80 from various ethnic backgrounds. For each person, we captured the RGBD data of her different expressions, including the neutral expression and 19 other expressions such as mouth-opening, smile, kiss, etc. For every RGBD raw data record, a set of facial feature points on the color image such as eye corners, mouth contour, and the nose tip are automatically localized, and manually adjusted if better accuracy is required. We then deform a template facial mesh to fit the depth data as closely as possible while matching the feature points on the color image to their corresponding points on the mesh. Starting from these fitted face meshes, we construct a set of individual-specific expression blendshapes for each person. These meshes with consistent topology are assembled as a rank-3 tensor to build a bilinear face model with two attributes: identity and expression. Compared with previous 3D facial databases, for every person in our database, there is a much richer matching collection of expressions, enabling depiction of most human facial actions. We demonstrate the potential of FaceWarehouse for visual computing with four applications: facial image manipulation, face component transfer, real-time performance-based facial image animation, and facial animation retargeting from video to image.

Systematic review and meta-analysis of robotic surgery compared with conventional laparoscopic and open resections for gastric carcinoma

BACKGROUND

Robot-assisted gastrectomy (RAG) has been developed in the hope of improving surgical quality and overcoming the limitations of conventional laparoscopically assisted gastrectomy (LAG) and open gastrectomy (OG) for gastric cancer. The aim of this study was to determine the extent of evidence in support of these ideals.

METHODS

A systematic review of the three operation types (RAG, LAG and OG) was carried out to evaluate short-term outcomes including duration of operation, retrieved lymph nodes, estimated blood loss, resection margin status, technical postoperative complications and hospital stay.

RESULTS

Nine non-randomized observational clinical studies involving 7200 patients satisfied the eligibility criteria. RAG was associated with longer operating times than LAG and OG (weighted mean difference 61.99 and 65.73 min respectively; P ≤ 0.001). The number of retrieved lymph nodes and the resection margin length in RAG were comparable with those of LAG and OG. Estimated blood loss as significantly less in RAG than in OG (P = 0.002), but not LAG. Mean hospital stay for RAG was similar to that for LAG (P = 0.14). In contrast, hospital stay was significantly shorter, by a mean of 2.18 days, for RAG compared with OG (P < 0.001). Postoperative complications were similar for all three operative approaches.

CONCLUSION

Short-term oncological outcomes of RAG were comparable with those of the other approaches. LAG was a shorter procedure and less expensive than RAG. Future studies involving RAG should focus on minimizing duration of operation and reducing cost.

Multiscale geometric modeling of macromolecules I: Cartesian representation

This paper focuses on the geometric modeling and computational algorithm development of biomolecular structures from two data sources: Protein Data Bank (PDB) and Electron Microscopy Data Bank (EMDB) in the Eulerian (or Cartesian) representation. Molecular surface (MS) contains non-smooth geometric singularities, such as cusps, tips and self-intersecting facets, which often lead to computational instabilities in molecular simulations, and violate the physical principle of surface free energy minimization. Variational multiscale surface definitions are proposed based on geometric flows and solvation analysis of biomolecular systems. Our approach leads to geometric and potential driven Laplace-Beltrami flows for biomolecular surface evolution and formation. The resulting surfaces are free of geometric singularities and minimize the total free energy of the biomolecular system. High order partial differential equation (PDE)-based nonlinear filters are employed for EMDB data processing. We show the efficacy of this approach in feature-preserving noise reduction. After the construction of protein multiresolution surfaces, we explore the analysis and characterization of surface morphology by using a variety of curvature definitions. Apart from the classical Gaussian curvature and mean curvature, maximum curvature, minimum curvature, shape index, and curvedness are also applied to macromolecular surface analysis for the first time. Our curvature analysis is uniquely coupled to the analysis of electrostatic surface potential, which is a by-product of our variational multiscale solvation models. As an expository investigation, we particularly emphasize the numerical algorithms and computational protocols for practical applications of the above multiscale geometric models. Such information may otherwise be scattered over the vast literature on this topic. Based on the curvature and electrostatic analysis from our multiresolution surfaces, we introduce a new concept, the polarized curvature, for the prediction of protein binding sites.

Multiscale geometric modeling of macromolecules II: Lagrangian representation

Geometric modeling of biomolecules plays an essential role in the conceptualization of biolmolecular structure, function, dynamics, and transport. Qualitatively, geometric modeling offers a basis for molecular visualization, which is crucial for the understanding of molecular structure and interactions. Quantitatively, geometric modeling bridges the gap between molecular information, such as that from X-ray, NMR, and cryo-electron microscopy, and theoretical/mathematical models, such as molecular dynamics, the Poisson-Boltzmann equation, and the Nernst-Planck equation. In this work, we present a family of variational multiscale geometric models for macromolecular systems. Our models are able to combine multiresolution geometric modeling with multiscale electrostatic modeling in a unified variational framework. We discuss a suite of techniques for molecular surface generation, molecular surface meshing, molecular volumetric meshing, and the estimation of Hadwiger's functionals. Emphasis is given to the multiresolution representations of biomolecules and the associated multiscale electrostatic analyses as well as multiresolution curvature characterizations. The resulting fine resolution representations of a biomolecular system enable the detailed analysis of solvent-solute interaction, and ion channel dynamics, whereas our coarse resolution representations highlight the compatibility of protein-ligand bindings and possibility of protein-protein interactions.

Immune tolerance of skin allograft transplantation induced by immature dendritic cells of a third party carrying donor antigens in mice

BACKGROUND

Dendritic cells (DCs) are the most powerful antigen-presenting cells in the body. Immature DCs (imDCs) can induce transplantation tolerance. In this study, using a mouse model of skin transplantation. We explored the antigen uptake by imDCs, changes in phenotype and function after antigen loading, as well as survival of skin grafts.

METHODS

Mononuclear cells from C57BL/6 mice mixed with a tritiated leucine ([(3)H]Leu) antigen supernate were incubated with Kunming mice imDC and mature DCs. We recorded the expressions of surface molecules that were detected using flow cytometry, mixed lymphocyte reactions, mean survival times, and postoperative morphological changes in skin grafts.

RESULTS

After the addition of allogeneic antigen supernate, the counts per minute of imDCs were significantly higher than those of mature DCs. The expression rates of I(A)/I(E) and CD80 significantly increased on the cell surface of imDCs. The counts per minute of imDCs in mixed lymphocyte reactions in the presence of allogeneic antigens was significantly higher than those of controls. Comparing mean survival times with controls, skin grafts were significantly longer in the imDCs groups from donors or from a third party carrying donor antigens.

CONCLUSIONS

ImDCs display a strong antigen uptake, gradually maturing in terms of phenotype and function after loading. Complementary application of cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin blocks the immune response of imDCs. Both imDCs from the third party carrying donor antigens and those from the donor strain can establish antigen-specific immune tolerance to allogeneic skin grafts.

Choking loops on surfaces

We present a method for computing "choking" loops--a set of surface loops that describe the narrowing of the volumes inside/outside of the surface and extend the notion of surface homology and homotopy loops. The intuition behind their definition is that a choking loop represents the region where an offset of the original surface would get pinched. Our generalized loops naturally include the usual 2g handles/tunnels computed based on the topology of the genus-g surface, but also include loops that identify chokepoints or bottlenecks, i.e., boundaries of small membranes separating the inside or outside volume of the surface into disconnected regions. Our definition is based on persistent homology theory, which gives a measure to topological structures, thus providing resilience to noise and a well-defined way to determine topological feature size. More precisely, the persistence computed here is based on the lower star filtration of the interior or exterior 3D domain with the distance field to the surface being the associated 3D Morse function.