Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 108
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Phys Rev Lett ; 132(21): 218201, 2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38856277

RESUMO

Amphiphiles self-assemble into a variety of bicontinuous mesophases whose equilibrium structures take the form of high-symmetry cubic networks. Here, we show that the symmetry-breaking distortions in these systems give rise to anomalously large, nonaffine collective deformations, which we argue to be a generic consequence of "mass equilibration" within deformed networks. We propose and study a minimal "liquid network" model of bicontinuous networks, in which acubic distortions are modeled by the relaxation of residually stressed mechanical networks with constant-tension bonds. We show that nonaffinity is strongly dependent on the valency of the network as well as the degree of strain-softening or strain-stiffening tension in the bonds. Taking diblock copolymer melts as a model system, liquid network theory captures quantitative features of two bicontinuous phases based on comparison with self-consistent field theory predictions and direct experimental characterization of acubic distortions, which are likely to be pronounced in soft amphiphilic systems more generally.

2.
Soc Sci Med ; 351 Suppl 1: 116879, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38825382

RESUMO

RATIONALE: Women's empowerment is a UN Sustainable Development Goal and a focus of global health and development but survey measures and data on gender empowerment remain weak. Existing indicators are often disconnected from theory; stronger operationalization is needed. OBJECTIVE: We present the EMERGE Framework to Measure Empowerment, a framework to strengthen empowerment measures for global health and development. METHOD: We initiated development of this framework in 2016 as part of EMERGE - an initiative designed to build the science of survey research and availability of high-quality survey measures and data on gender empowerment. The framework is guided by existing theories of empowerment, evidence, and expert input. We apply this framework to understand women's empowerment in family planning (FP) via review of state of the field measures. RESULTS: Our framework offers concrete measurable constructs to assess critical consciousness and choice, agency and backlash, and goal achievement as the empowerment process, recognizing its operation at multiple levels-from the individual to the collective. Internal attributes, social norms, and external contexts and resources create facilitators or barriers to the empowerment process. Review of best evidence FP measures assessing empowerment constructs, social norms, and key influencers (e.g., partners and providers) show a strong landscape of measures, including those with women, partners, and providers, but they are limited in assessing translation of choice to agency to achievement of women's self-determined fertility or contraceptive goals, instead relying on assumption of contraceptive use as the goal. We see no measures on collective empowerment toward women's reproductive choice and rights. CONCLUSION: The EMERGE Framework can guide development and analysis of survey measures on empowerment and is needed as the current state of the field shows limited coverage of empowerment constructs even in areas which have received more study, such as family planning.


Assuntos
Empoderamento , Humanos , Feminino , Saúde Global , Serviços de Planejamento Familiar/métodos , Inquéritos e Questionários , Poder Psicológico , Normas Sociais
3.
ACS Nano ; 18(13): 9443-9450, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38466943

RESUMO

Transitions between gyroid and diamond intercatenated double network phases occur in many types of soft matter, but to date, the structural pathway and the crystallographic relationships remain unclear. Slice and view scanning electron microscopy tomography of a diblock copolymer affords monitoring of the evolving shape of the intermaterial dividing surface, allowing structural characterization of both the majority and minority domains. Two trihedral malleable mesoatoms combine to form a single tetrahedral mesoatom in a volume additive manner while preserving network topology, as the types of loops, the number of mesoatoms in a loop, minority domain strut lengths, and directions that connect a given mesoatom to its neighbors evolve across a 150 nm wide transition zone (TZ). The [111]DD direction is coincident with the [110]DG direction so that the (111)DD and (110)DG planes define the boundaries of the TZ. Selection of the particular crystal orientations and direction and width of the transition zone is to minimize the cost of morphing the mesoatoms from one structure to the other, by maximizing like-block continuity and minimizing the variation of the surface curvature and thickness of the domains across the TZ. Such coherent continuity of the independent, intercatenated networks across the transition zone is critical for applications such as graded mechanical trusses where the pair of different networks are joined to provide different mechanical properties for adjacent grains or could serve as a nanoscale anode/cathode allowing super charging and discharging provided the networks are continuous and rigorously separate.

4.
Small ; 20(14): e2307487, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37985946

RESUMO

By utilizing bicontinuous and nanoporous ordered nanonetworks, such as double gyroid (DG) and double diamond (DD), metamaterials with exceptional optical and mechanical properties can be fabricated through the templating synthesis of functional materials. However, the volume fraction range of DG in block copolymers is significantly narrow, making it unable to vary its porosity and surface-to-volume ratio. Here, the theoretically limited structural volume of the DG phase in coil-coil copolymers is overcome by enlarging the conformational asymmetry through the association of mesogens, providing fast access to achieving flexible structured materials of ultra-high porosities. The new materials design, dual-extractable nanocomposite, is created by incorporating a photodegradable block with a solvent-extractable mesogen (m) into an accepting block, resulting in a new hollow gyroid (HG) with the largely increased surface-to-volume ratio and porosity of 77 vol%. The lightweight HG exhibits a low refractive index of 1.11 and a very high specific reduced modulus, almost two times that of the typical negative gyroid (porosity≈53%) and three times that of the positive gyroid (porosity≈24%). This novel concept can significantly extend the DG phase window of block copolymers and the corresponding surface-to-volume ratio, being applicable for nanotemplate-synthesized nanomaterials with a great gain of mechanical, catalytic, and optoelectronic properties.

7.
BMC Pregnancy Childbirth ; 23(1): 519, 2023 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-37454051

RESUMO

BACKGROUND: Linking family planning with infant vaccination care has the potential to increase contraceptive use among postpartum women in rural settings. We explored the multilevel factors that can facilitate or impede uptake of contraception at the time of infant vaccination among postpartum women and couples in rural Maharashtra, India. METHODS: We conducted 60 semi-structured interviews with key stakeholders including: postpartum married women (n = 20), husbands (n = 10), and mothers-in-law (n = 10) of postpartum women, frontline healthcare workers (auxiliary nurse midwives (ANMs) and Accredited Social Health Activists (ASHAs), (n = 10), and community leaders (physician medical officers and village panchayat leaders) (n = 10). We sought to assess the feasibility and acceptability of delivering community-based postpartum family planning care in rural India at the time of infant vaccination. The Consolidated Framework for Implementation Research (CFIR) was used to design a structured interview guide and codebook. Data were analyzed via directed content analysis. RESULTS: Three major themes emerged: (1) Social fertility and gender norms including son preference and male control over contraceptive decision-making influence postpartum contraceptive access and choice. (2) Linking contraceptive care and infant vaccination is perceived as potentially feasible and acceptable to implement by families, health workers, and community leaders. The intervention provides care to women and families in a convenient way where they are in their community. (3) Barriers and facilitators to linked infant postpartum contraception and infant vaccination were identified across the five CFIR domains. Key barriers included limited staff and space (inner setting), and contraceptive method targets for clinics and financial incentives for clinicians who provide specific methods (outer setting). Key facilitators included convenience of timing and location for families (intervention characteristics), the opportunity to engage husbands in decision-making when they attend infant vaccination visits (participant characteristics), and programmatic support from governmental and community leaders (process of implementation). CONCLUSIONS: Linked provision of family planning and infant vaccination care may be feasible and accessible in rural India utilizing strategies identified to reduce barriers and facilitate provision of care. A gender-transformative intervention that addresses gender and social norms has greater potential to impact reproductive autonomy and couples' contraceptive decision-making.


Assuntos
Serviços de Planejamento Familiar , Educação Sexual , Humanos , Masculino , Feminino , Lactente , Estudos de Viabilidade , Índia , Anticoncepcionais
8.
Stud Fam Plann ; 54(1): 39-61, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36691257

RESUMO

Social norms related to fertility may be driving pregnancy desire, timing and contraceptive use, but measurement has lagged. We validated a 10-item injunctive Fertility Norms Scale (FNS) and examined its associations with family planning outcomes among 1021 women and 1020 men in India. FNS captured expectations around pronatalism, childbearing early in marriage and community pressure. We assessed reliability and construct validity through Cronbach's alpha and exploratory factor analysis (EFA) respectively, examining associations with childbearing intention and contraceptive use. FNS demonstrated good reliability (α = 0.65-0.71) and differing sub-constructs by gender. High fertility norm among women was associated with greater likelihood of pregnancy intention [RRR = 2.35 (95% CI: 1.25,4.39); ARRR = 1.53 (95% CI: 0.70,3.30)], lower likelihood of delaying pregnancy [RRR = 0.69 (95% CI: 0.50,0.96); ARRR = 0.72 (95% CI: 0.51,1.02)] and greater ambivalence on delaying pregnancy [RRR = 1.92 (95% CI: 1.18,3.14); ARRR = 1.99 (95% CI: 1.21,3.28)]. Women's higher FNS scores were also associated with higher sterilization [RRR = 2.17 (95% CI: 1.28,3.66); ARRR = 2.24 (95% CI: 1.32,3.83)], but the reverse was noted for men [RRR = 0.61 (95% CI: 0.36,1.04); ARRR = 0.54 (95% CI: 0.32,0.94)]. FNS indicated better predictive value among women compared to men for key reproductive outcomes. This measure may be useful for social norms-focused evaluations in family planning and warrants cross-contextual study.


Assuntos
Anticoncepção , Anticoncepcionais , Gravidez , Masculino , Feminino , Humanos , Intenção , Reprodutibilidade dos Testes , Fertilidade , Serviços de Planejamento Familiar , Índia , Comportamento Contraceptivo
9.
Proc Natl Acad Sci U S A ; 120(4): e2213441120, 2023 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-36649431

RESUMO

A twin boundary (TB) is a common low energy planar defect in crystals including those with the atomic diamond structure (C, Si, Ge, etc.). We study twins in a self-assembled soft matter block copolymer (BCP) supramolecular crystal having the double diamond (DD) structure, consisting of two translationally shifted, interpenetrating diamond networks of the minority polydimethyl siloxane block embedded in a polystyrene block matrix. The coherent, low energy, mirror-symmetric double tubular network twin has one minority block network with its nodes offset from the (222) TB plane, while nodes of the second network lie in the plane of the boundary. The offset network, although at a scale about a factor of 103 larger, has precisely the same geometry and symmetry as a (111) twin in atomic single diamond where the tetrahedral units spanning the TB retain nearly the same strut (bond) lengths and strut (bond) angles as in the normal unit cell. In DD, the second network undergoes a dramatic restructuring-the tetrahedral nodes transform into two new types of mirror-symmetric nodes (pentahedral and trihedral) which alternate and link to form a hexagonal mesh in the plane of the TB. The collective reorganization of the supramolecular packing highlights the hierarchical structure of ordered BCP phases and emphasizes the remarkable malleability of soft matter.


Assuntos
Bandagens , Diamante , Grupos Minoritários , Polímeros , Poliestirenos
10.
SSM Popul Health ; 19: 101234, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36203476

RESUMO

Intra-uterine devices (IUDs) are a safe and effective method to delay or space pregnancies and are available for free or at low cost in the Indian public health system; yet, IUD uptake in India remains low. Limited quantitative research using national data has explored factors that may affect IUD use. Machine Learning (ML) techniques allow us to explore determinants of low prevalence behaviors in survey research, such as IUD use. We applied ML to explore the determinants of IUD use in India among married women in the 4th National Family Health Survey (NFHS-4; N = 499,627), which collects data on demographic and health indicators among women of childbearing age. We conducted ML logistic regression (lasso and ridge) and neural network approaches to assess significant determinants and used iterative thematic analysis (ITA) to offer insight into related variable constructs generated from a series of regularized models. We found that couples' shared family planning (FP) goals were the strongest determinants of IUD use, followed by receipt of FP services and desire for no more children, higher wealth and education, and receipt of maternal and child health services. Findings highlight the importance of male engagement and family planning services for IUD uptake and the need for more targeted efforts to support awareness of IUD as an option for spacing, especially for those of lower SES and with lower access to care.

12.
Sci Adv ; 8(10): eabm5120, 2022 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-35275730

RESUMO

Stimuli-interactive structural color (SC) of a block copolymer (BCP) photonic crystal (PC) uses reversible alteration of the PC using external fluids and applied forces. The origin of the diffusional pathways of a stimulating fluid into a BCP PC has not been examined. Here, we directly visualize the vertically oriented screw dislocations in a one-dimensional lamellar BCP PC that facilitate the rapid response of visible SC. To reveal the diffusional pathway of the solvent via the dislocations, BCP lamellae are swollen with an interpenetrated hydrogel network, allowing fixation of the swollen state and subsequent microscopic examination. The visualized defects are low-energy helicoidal screw dislocations having unique, nonsingular cores. Location and areal density of these dislocations are determined by periodic concentric topographic nanopatterns of the upper surface-reconstructed layer. The nonsingular nature of the interlayer connectivity in the core region demonstrates the beneficial nature of these defects on sensing dynamics.

13.
ACS Appl Mater Interfaces ; 14(1): 1861-1873, 2022 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-34978172

RESUMO

Two-dimensional (2D) rigid polymers provide an opportunity to translate the high-strength, high-modulus mechanical performance of classic rigid-rod 1D polymers across a plane by extending covalent bonding into two dimensions while simultaneously reducing density due to microporosity by structural design. Thus far, this potential has remained elusive because of the challenge of producing high-quality 2D polymer thin films, particularly those with irreversible, rigid benzazole linkages. Here, we present a facile two-step process that allows the deposition of a uniform intermediate film network via reversible, non-covalent interactions, followed by a subsequent solid-state annealing step that facilitates the irreversible conversion to a 2D covalently bonded polymer product with benzoxazole linkages. We demonstrate the versatility of this synthesis method by producing films with four different aromatic core units. The resulting films show microporosity and anisotropy with a 2D layered structure that can be exfoliated into few-layer nanosheets using a freeze-thaw method. These films have promising mechanical properties with an in-plane ultimate tensile strength of nearly 40 MPa and axial tensile and transverse compressive elastic moduli on the scale of several GPa, rivaling the performance of solution-cast films of 1D polybenzoxazole, as well as several other 1D high-strength polymer films.

14.
Int. arch. otorhinolaryngol. (Impr.) ; 25(3): 392-398, Jul.-Sept. 2021. tab, graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1340008

RESUMO

Abstract Introduction The middle cranial fossa approach is performed by fewer neurotologists owing to a reduced number of indications. Consistent landmarks are mandatory to guide the surgeon in a narrow field. Objectives We have evaluated the incus and malleus head and the incudomalleal joint (IMJ) as a key landmark for identifying the superior semicircular canal (SSC) and to get oriented along the floor of the middle cranial fossa. Methods A combination of 20 temporal bone dissections and CT imaging were utilized to test and describe these landmarks. Results The blue line of the SSC is consistently identified along the prolongation of a virtual line through the IMJ and the angulation toward the root of zygoma. The mean distance from the zygoma toward the IMJ ranged from 1.60 to 1.90cm. Once the IMJ was identified, the blue line of the SSC was consistently found along the virtual line through the IMJ within 5 to 9mm. Conclusions The IMJ is a safe and consistent anatomical marker in the surgical approach to the middle cranial fossa floor. Opening the tegmen 1.5 to 2cm medial to the root of the zygoma and identifying the joint allows to trace a virtual line toward the SSC within 5 to 9mm. Knowledge of the close relationship between the direction of the IMJ and the superior canal can be used in all transtemporal approaches, thus orienting the surgeon in a rather narrow field with limited retraction of the dura and brain.

15.
Int Arch Otorhinolaryngol ; 25(3): e392-e398, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34377174

RESUMO

Introduction The middle cranial fossa approach is performed by fewer neurotologists owing to a reduced number of indications. Consistent landmarks are mandatory to guide the surgeon in a narrow field. Objectives We have evaluated the incus and malleus head and the incudomalleal joint (IMJ) as a key landmark for identifying the superior semicircular canal (SSC) and to get oriented along the floor of the middle cranial fossa. Methods A combination of 20 temporal bone dissections and CT imaging were utilized to test and describe these landmarks. Results The blue line of the SSC is consistently identified along the prolongation of a virtual line through the IMJ and the angulation toward the root of zygoma. The mean distance from the zygoma toward the IMJ ranged from 1.60 to 1.90cm. Once the IMJ was identified, the blue line of the SSC was consistently found along the virtual line through the IMJ within 5 to 9mm. Conclusions The IMJ is a safe and consistent anatomical marker in the surgical approach to the middle cranial fossa floor. Opening the tegmen 1.5 to 2cm medial to the root of the zygoma and identifying the joint allows to trace a virtual line toward the SSC within 5 to 9mm. Knowledge of the close relationship between the direction of the IMJ and the superior canal can be used in all transtemporal approaches, thus orienting the surgeon in a rather narrow field with limited retraction of the dura and brain.

16.
Clin Case Rep ; 9(4): 2016-2018, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33936632

RESUMO

Involvement of the external ear by PG is a rare encounter, and steroids remain to be the main stay in its treatment.

17.
Int Arch Otorhinolaryngol ; 25(2): e224-e228, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33968224

RESUMO

Introduction Chronic otitis media (COM) with a central perforation or a concomitant cholesteatoma are both inflammatory lesions, however, with different etiologies. Both entities may present with an intact chain, and the final reconstruction is quite similar. Does it also apply for the hearing outcome? Objectives In a retrospective analysis, we investigated the preoperative hearing and the final hearing outcome of two groups of patients: those with COM and those with cholesteatoma, and compared various factors. Methods Patients operated between 2010 and 2019 were entered prospectively into a research database, and the integrity of the ossicular chain, the extent of the cholesteatoma, and the findings on computed tomography (CT) scans were retrospectively analyzed and correlated to the final hearing outcome. Results Out of 210 tympanoplasties for COM, 162 (80%) presented with an intact chain, and 85 (40%) ears could be analyzed. Out of 283 cholesteatoma surgeries, 53 (19%) ears presented with an intact chain. The preoperative air-bone gap (ABG) was worse in the COM group, but the postoperative ABG over the frequencies of 0.5 kHz and 4 kHz was the same (10 dB to 12 dB) in both groups, and remained within 20 dB in 90% (40 and 78 patients, respectively). The extension of the disease was rather limited in the cholesteatoma group (stages Ch1a and 1b), and better pneumatization and ventilation were beneficial for a good result. Postoperatively, the frequency of 4 kHz had the largest ABG (14 dB and 18 dB). Conclusion Overall, 80% of the patients with COM and less than 20% of those with cholesteatoma had an intact and mobile chain at surgery. Using equivalent surgical techniques for the tympanoplasty, the final outcome was almost the same for both groups, with a mean ABG of 10 dB to 12 dB.

18.
Nano Lett ; 21(8): 3355-3363, 2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33856816

RESUMO

Herein, we aim to develop a facile method for the fabrication of mechanical metamaterials from templated polymerization of thermosets including phenolic and epoxy resins using self-assembled block copolymer, polystyrene-polydimethylsiloxane with tripod network (gyroid), and tetrapod network (diamond) structures, as templates. Nanoindentation studies on the nanonetwork thermosets fabricated reveal enhanced energy dissipation from intrinsic brittle thermosets due to the deliberate structuring; the calculated energy dissipation for gyroid phenolic resins is 0.23 nJ whereas the one with diamond structure gives a value of 0.33 nJ. Consistently, the gyroid-structured epoxy gives a high energy dissipation value of 0.57 nJ, and the one with diamond structure could reach 0.78 nJ. These enhanced properties are attributed to the isotropic periodicity of the nanonetwork texture with plastic deformation, and the higher number of struts in the tetrapod diamond network in contrast to tripod gyroid, as confirmed by the finite element analysis.

19.
Int. arch. otorhinolaryngol. (Impr.) ; 25(2): 224-228, Apr.-June 2021. tab
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1286743

RESUMO

Abstract Introduction Chronic otitis media (COM) with a central perforation or a concomitant cholesteatoma are both inflammatory lesions, however, with different etiologies. Both entities may present with an intact chain, and the final reconstruction is quite similar. Does it also apply for the hearing outcome? Objectives In a retrospective analysis, we investigated the preoperative hearing and the final hearing outcome of two groups of patients: those with COM and those with cholesteatoma, and compared various factors. Methods Patients operated between 2010 and 2019 were entered prospectively into a research database, and the integrity of the ossicular chain, the extent of the cholesteatoma, and the findings on computed tomography (CT) scans were retrospectively analyzed and correlated to the final hearing outcome. Results Out of 210 tympanoplasties for COM, 162 (80%) presented with an intact chain, and 85 (40%) ears could be analyzed. Out of 283 cholesteatoma surgeries, 53 (19%) ears presented with an intact chain. The preoperative air-bone gap (ABG) was worse in the COM group, but the postoperative ABG over the frequencies of 0.5 kHz and 4 kHz was the same (10 dB to 12 dB) in both groups, and remained within 20 dB in 90% (40 and 78 patients, respectively). The extension of the disease was rather limited in the cholesteatoma group (stages Ch1a and 1b), and better pneumatization and ventilation were beneficial for a good result. Postoperatively, the frequency of 4 kHz had the largest ABG (14 dB and 18 dB). Conclusion Overall, 80% of the patients with COM and less than 20% of those with cholesteatoma had an intact and mobile chain at surgery. Using equivalent surgical techniques for the tympanoplasty, the final outcome was almost the same for both groups, with a mean ABG of 10 dB to 12 dB.

20.
Adv Sci (Weinh) ; 8(6): 2003142, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33747728

RESUMO

Thin layered mats comprised of an interconnected meandering network of multiwall carbon nanotubes (MWCNT) are subjected to a hypersonic micro-projectile impact test. The mat morphology is highly compliant and while this leads to rather modest quasi-static mechanical properties, at the extreme strain rates and large strains resulting from ballistic impact, the MWCNT structure has the ability to reconfigure resulting in extraordinary kinetic energy (KE) absorption. The KE of the projectile is dissipated via frictional interactions, adiabatic heating, tube stretching, and ultimately fracture of taut tubes and the newly formed fibrils. The energy absorbed per unit mass of the film can range from 7-12 MJ kg-1, much greater than any other material.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...