Physics-informed neural network for phase imaging based on transport of intensity equation.

Non-interferometric quantitative phase imaging based on Transport of Intensity Equation (TIE) has been widely used in bio-medical imaging. However, analytic TIE phase retrieval is prone to low-spatial frequency noise amplification, which is caused by the illposedness of inversion at the origin of the spectrum. There are also retrieval ambiguities resulting from the lack of sensitivity to the curl component of the Poynting vector occurring with strong absorption. Here, we establish a physics-informed neural network (PINN) to address these issues, by integrating the forward and inverse physics models into a cascaded deep neural network. We demonstrate that the proposed PINN is efficiently trained using a small set of sample data, enabling the conversion of noise-corrupted 2-shot TIE phase retrievals to high quality phase images under partially coherent LED illumination. The efficacy of the proposed approach is demonstrated by both simulation using a standard image database and experiment using human buccal epitehlial cells. In particular, high image quality (SSIM = 0.919) is achieved experimentally using a reduced size of labeled data (140 image pairs). We discuss the robustness of the proposed approach against insufficient training data, and demonstrate that the parallel architecture of PINN is efficient for transfer learning.

In situ melt pool measurements for laser powder bed fusion using multi sensing and correlation analysis.

Laser powder bed fusion is a promising technology for local deposition and microstructure control, but it suffers from defects such as delamination and porosity due to the lack of understanding of melt pool dynamics. To study the fundamental behavior of the melt pool, both geometric and thermal sensing with high spatial and temporal resolutions are necessary. This work applies and integrates three advanced sensing technologies: synchrotron X-ray imaging, high-speed IR camera, and high-spatial-resolution IR camera to characterize the evolution of the melt pool shape, keyhole, vapor plume, and thermal evolution in Ti-6Al-4V and 410 stainless steel spot melt cases. Aside from presenting the sensing capability, this paper develops an effective algorithm for high-speed X-ray imaging data to identify melt pool geometries accurately. Preprocessing methods are also implemented for the IR data to estimate the emissivity value and extrapolate the saturated pixels. Quantifications on boundary velocities, melt pool dimensions, thermal gradients, and cooling rates are performed, enabling future comprehensive melt pool dynamics and microstructure analysis. The study discovers a strong correlation between the thermal and X-ray data, demonstrating the feasibility of using relatively cheap IR cameras to predict features that currently can only be captured using costly synchrotron X-ray imaging. Such correlation can be used for future thermal-based melt pool control and model validation.

The Impact of Inventory Management on Stock-Outs of Essential Drugs in Sub-Saharan Africa: Secondary Analysis of a Field Experiment in Zambia.

OBJECTIVE: To characterize the impact of widespread inventory management policies on stock-outs of essential drugs in Zambia's health clinics and develop related recommendations. METHODS: Daily clinic storeroom stock levels of artemether-lumefantrine (AL) products in 2009-2010 were captured in 145 facilities through photography and manual transcription of paper forms, then used to determine historical stock-out levels and estimate demand patterns. Delivery lead-times and estimates of monthly facility accessibility were obtained through worker surveys. A simulation model was constructed and validated for predictive accuracy against historical stock-outs, then used to evaluate various changes potentially affecting product availability. FINDINGS: While almost no stock-outs of AL products were observed during Q4 2009 consistent with primary analysis, up to 30% of surveyed facilities stocked out of some AL product during Q1 2010 despite ample inventory being simultaneously available at the national warehouse. Simulation experiments closely reproduced these results and linked them to the use of average past monthly issues and failure to capture lead-time variability in current inventory control policies. Several inventory policy enhancements currently recommended by USAID | DELIVER were found to have limited impact on product availability. CONCLUSIONS: Inventory control policies widely recommended and used for distributing medicines in sub-Saharan Africa directly account for a substantial fraction of stock-outs observed in common situations involving demand seasonality and facility access interruptions. Developing central capabilities in peripheral demand forecasting and inventory control is critical. More rigorous independent peer-reviewed research on pharmaceutical supply chain management in low-income countries is needed.

Ho:YAG Laser Endopyelotomy is effective for primary and secondary UPJOs.

PURPOSE: To assess efficacy of laser endopyelotomy in both primary and secondary ureteropelvic junction obstructions (UPJOs) PATIENTS AND METHODS: Primary category consisted of 10 patients of congenital UPJOs. Secondary category was comprised of UPJOs in 12 status post pyeloplasty, 10 status post lithotomy, 5 status post shock wave lithotripsy, and 10 status post ureteroscopic lithotripsy. Ho:YAG laser endopyelotomy was performed in all subjects. Exclusion criteria included obstructions longer than 2 cm, ipsilateral upper urinary calculi and crossing vasculature. RESULTS: Mean operation time was 44 min. Average inpatient duration was 1.87 days. No major complication occurred. Follow-ups were at least 12 months. Success rate for single endopyelotomy was 82.5%, leaving 7 patients for a secondary endopyelotomy. Secondary UPJO due to failed pyeloplasty had a predilection of restenosis after endopyelotomy (P = 0.0005) compared to other aetiologies. CONCLUSIONS: Ho:YAG laser endopyelotomy is a safe and effective approach effective in both primary and secondary UPJO treatments.

Measurement of enhanced radiation force on a parallel metallic-plate system in the microwave regime.

We measure the force exerted by microwave radiation on a centimeter-sized parallel-plate metallic resonant unit. By varying the ambient environment, we distinguish carefully between the direct radiation force and the indirect photothermal component. At the microwave resonance, the former is measured quantitatively to be 100 times larger than the conventional radiation force. Furthermore, the enhanced radiation force tends to increase the separation of the plates. Both the direction and the magnitude of the measured force agree well with numerical calculations.

Strong light-induced negative optical pressure arising from kinetic energy of conduction electrons in plasmon-type cavities.

We found that very strong negative optical pressure can be induced in plasmonic cavities by LC resonance. This interesting effect could be described qualitatively by a Lagrangian model which shows that the negative optical pressure is driven by the internal inductance and the kinetic energy of the conduction electrons. If the metal is replaced by perfect conductors, the optical pressure becomes much smaller and positive.

Optical transmission through double-layer, laterally shifted metallic subwavelength hole arrays.

We measure the transmission of IR radiation through double-layer metal films with periodic arrays of subwavelength holes. When the two metal films are placed in sufficiently close proximity, two types of transmission resonances emerge. For the surface plasmon mode, the electromagnetic field is concentrated on the outer surface of the entire metallic layer stack. In contrast, for the guided mode, the field is confined to the gap between the two metal layers. Our measurements indicate that, as the two layers are laterally shifted from perfect alignment, the peak transmission frequency of the guided mode decreases significantly, while that of the surface plasmon mode remains largely unchanged, in agreement with numerical calculations.

[The relationship between arteriolar pathological changes and brain hemorrhage in primary hypertension cases].

This study was intended to elucidate the relationship between arteriolar pathological changes and encephalorrhagia in the cases of primary hypertension. Gross anatomy and histology of brain were observed in autopsy of 45 cases of primary hypertension. Forty cases of arteriolar hyalinization including 26 cases of brain hemorrhage were found in those 45 cases of primary hypertension. The hyalinized arterioles were divided to two types. One is characterized by the narrow lumen of terminal arterioles, the other by the dilatant lumen of proximal arterioles. Hemorrhage always occurred in the latter type. Besides these changes, 3 cases of acute necrosis and 5 cases of atherosclerosis in arterioles were related to hemorrhage. These data suggest that brain hemorrhage of primary hypertension mainly occur in dilated and hyalinized arterioles, and some cases are probably related to acute necrosis or atheroscleromatous atrerioles.

[Pathological morphology of arterioles and main visceal organs in primary hypertension--an analysis of 45 autopsies].

The autopsy materials of 45 cases of primary hypertension were studied retrospectively. The arteriolar lesions were reviewed. The arterioles < 100 microns in diameter were defined as distal arterioles; those > or = 100 microns and < 300 microns in diameter were proximal arterioles. The lesions of arteriolar wall were categorized as plasma infiltration and hyaline degeneration, and according to seriousness, the latter was divided into three degrees: I, II and III. The results revealed that (1) the arteriolar lesions in different areas of the body were at different stages of seriousness; (2) the changes in the distal arterioles were earlier than those in the proximal ones; in brain, the proximal arterioles dilated first, and then occurred the hyline degeneration; (3) hyaline degeneration took place early in the abdominal organs such as kidney, liver and pancreas, but relatively late in brain; (4) different parts of an organ were at different stages of seriousness; and (5) the lesions in different organs led to different consequences. The pathogenesis of arteriolar sclerosis in primary hypertension was also discussed.

[An analysis of DNA content in 405 cases of human tumor by flow cytometry].

This study was intended to evaluate the relationship between the DNA content of cell cycle and the histology in human tumors. We detected the DNA content in 405 cases of fresh human tumor tissue by means of flow cytometry and observed the histology of tumor with light microscopy. The occurrences of aneuploidy in 22 cases of benign tumor and 383 cases of malignant tumor were 27% and 52% respectively. There were differences in aneuploidy in different histologic types of tumor. The aneuploidy in adenocarcinoma was about 50%, that in sarcoma was more than 37%, and that in squamous carcinoma less than 17%. S > or = 10, G2/m > or = 10 or S > or = 20, G2/m > or = 5 were present in malignant tumors, but were not found in benign tumors. The results suggest that there is obvious difference in the occurrences of aneuploidy in benign and malignant tumors and in different histologic type of tumor(P < 0.05). Benign and malignant tumor may be distinguished when SPF and G2/m reach a higher level (P < 0.01).

[Pathological analysis of 180 cases of cerebrovascular disorder in autopsy].

OBJECTIVE: To evaluate the ratio of each kind of causes in 180 cases of cerebrovascular disorder(CVD) in autopsy. RESULTS: In 180 cases of CVD in autopsy: (1)125 (69%) belong to brain hemorrhage including hypertension 36 cases(20%), vascular malformation 28 cases(16%), hemopoitic diseases and blood coagulation disturbances 23 cases(13%), congenital aneurysm and brain tumor 9 cases(5%) each separately. (2) 55 cases (31%) are due to brain infarction, main of them are caused by embolism 29 cases (16%) and thrombosis 17 cases(10%). Thrombosis related to atherosclerosis has 5 cases(3%). CONCLUSION: In CVD in autopsy, brain hemorrhage is more than infarction, the ratio of them is 2.3:1. More than 50% of cases is due to hypertension and vascular malformation. In infarction, embolism is more than thrombosis, the ratio of them is 1.7:1. Vascular malformation is more than congenital aneurysm, the ratio of them is 3:1.

[Pathologic grading and differential diagnosis on oligodendroglioma].

UNLABELLED: To investigate the histological characteristics of oligodendroglioma (ODG), 65 cases of ODG were observed with light microscopy and partially with immunohistochemistry. According to WHO classification of tumors, 65 cases of ODG were graded in degree of differentiation of tumor cells. Of these, 19 cases belonged to grade I, 32 grade II, and 14 grade III. CONCLUSION: Except the degree of differentiation, some other criterlons as cellular density, mitotic activities, and the presence of focally concentrated apoptotic cells are closely related to grading of ODG.

[Observation on oligodendroglioma with light, electron microscopy and immunohistochemistry].

OBJECTIVE: To investigate the ultrastructural and histological characteristics of oligodendroglioma (ODG). METHODS: By means of light microscopy and partially electron microscopy and immunohistochemistry, 65 cases of ODG were observed. RESULTS: According to WHO classification of the tumor, all 65 cases of ODG were graded in the degree of differentiation of tumor cells, showing 19 cases of Grade I, 32 cases of Grade II and 14 cases of Grade III. CONCLUSIONS: (1) The presence of glial filaments in tumor cells may be explained as a heterogeneity in differentiation. (2) Besides the degree of differentiation, some other criteria such as cellular density and mitotic activity are also closely related to the grading of ODG.

[Histopathologic and immunochemical changes in Sjögren's syndrome].

To research into the causes of sjögren's syndrome, we investigated the lacrimal gland tissues of 6 cases of sjogren's syndriome by using electronmicroscopy and immunochemical methods. The results revealed that at the early stage the lacrimal gland cells showed degeneration, irregular arrangement and many intracellular vacuoles. At the middle stage, some lymphocytes infliltrated into the gland tissues. And at the advanced stage, lymphocytes and collagenous fibers were there in substitution of gland cells.

[Aneurysmal bone cyst: imaging diagnosis and evaluation of therapeutic methods].

OBJECTIVE: To determine the imaging features and useful therapeutic methods of aneurysmal bone cyst (ABC). METHODS: The radiographs, CT, and MR scans of 82 cases of pathologically proved ABC were retrospectively analyzed. Post-therapeutic follow-up of 45 cases was carried out for 3 months to 24 years. RESULTS: Plain radiographs showed eccentric expansile osteolysis in most cases. Fluid-fluid level was seen in 21/27 cases on CT scans, and calcification or ossification in 11/27 cases. MR images showed a hypointense rim in 7/7 cases, multilocular hyperintense cysts with hypointense septae on T2WI in 6/7 cases, and fluid-fluid levels in 5/7 cases. CONCLUSION: CT and MR scans are superior to plain radiographs in the diagnosis of ABC in the osteolytic phase and in the axial skeleton. Curettage combined with bone graft surgery is the most effective therapeutic method for ABC of the extremities. Arterial embolization with or without surgery is valuble for the treatment of ABC arising from the axial skeleton.

[Electron microscopic observation of hepato-cellular carcinoma in 15 cases--an ultrastructural comparison with human embryonic liver].

An ultrastructural comparison between 15 cases of hepatocellular carcinoma (HCC) and 5 cases of human embryonic liver (HEL) was performed. There were similarities. Both of them are polygonal in cell shape with a central nucleus and are abundant in RER and mitochondria; both have laminating form of RER and formation of bile capillary and perisinusoid space. These are important evidences for diagnosis of a tumor originating from hepatic cells. On the other hand, obvious differences were present between HCC and HEL. Cancer cells possess certain characteristics; they are pleomorphic and heterogeneitic; the differentiation of their ultrastructural components is not synchronic, and they are invasive in growth. These enable us to suspect the malignancy of a tumor. In addition, single death cancer cells with pyknotic nucleus were seen in HCC; some of them were phagocytozed by adjacent cells. We conside these are apoptosis even no formation of apoptoic bodies was found. In the majority of HCC cases, lymphocyte-mediated cancer cell lyses by both T-lymphocytes and large granular lymphocytes (nature killer cell) were found.

[A pathological analysis of 180 cases of vascular malformation of brain].

180 cases of vascular malformation in brain (BVM) including 156 cases of brain biopsy and 24 autopsy cases were examined with routine pathological methods. The attempt of this study is to realize the pathological change and incidnce of each type and to find out the main cause of hemorrhage in BVM. According the morphological characteristics, 180 cases of BVM were classified into five types. They are: arteriovenous type 159 cases, venous type 3 cases, cavernous type 6 cases, capillary telangiectasis 1 case, and mixed type 11 cases. Hemorrhage was the most common clinical manifestation and main cause of death in BVM. The mechanism of hemorrhage may be due to either hemodynamic disturbance in local area or changes of the blood vessel wall. Besides these, there are five cases of BVM accompanied with brain tumor. They may be two independent diseases occurred in the same person. No relationship was found between the occurrence of these 2 entities.

[An ultrastructural study of the ependymoma cells and cells of the ventric zone and neural canal of embryonic brain].

In order to make clear the characteristics of cell differentiation in ependymoma, 12 ependymoma cases were studied with light and electronic microscopy, and the tumor cells were compared with cells of the ventric zone and neural canal from 8 embryonic brains. 10 out of 12 ependymoma cases were also studied with immunohistochemistry staining. According to the ultrastructural findings, four types of ependymoma were classified, namely, the primary neuroectodermal tumor with ependymoblast differentiation, the ependymoblastoma, the ependymoma, and the subependymoma. Some ultrastructural features, such as long intermediate junction and microrosette formation were considered as the important criterion for differential diagnosis,. Neuroendocrine granulas were found in one case of 12 ependymomas which is considered to be heterogenic in differentiation.

[A comparison between astrocytoma cells and the developing astrocytes in human embryo brain by electron microscopy].

60 cases of astrocytoma of brain and 8 human embryo brains were studied with light and electron microscopy. The 5 types of tumor cells in astrocytoma include the undifferentiated, pre-astrocyte, astrocyte gemistocyte and tumor giant cells. Some similarities were found between the ultrastructure of astrocytoma and that of the developing astrocyte, the tumor cells somewhat resembling the cells of developing astrocytes. But certain differences were observed, the tumor cells were usually polymorphic with increased chromatin in nucleus, and asynchronism between nucleus and cytoplasm differentiation was sometimes found. The current nomenclature and classification of astrocytoma were evaluated and discussed, the author's opinion on classification was presented.

[Recurrent astrocytoma versus primary astrocytoma: a comparative study of morphological changes of 32 cases].

The pathologic morphological changes of 32 cases of recurrent astrocytoma (RA) and primary astrocytoma were reported. During recurrence, 20 cases (62.5%) of astrocytomas transformed into cases at higher grades. Twelve cases remained at the same grades as primary tumors. Among 21 cases of RA at grades III and IV, 15 cases (71.4%) came from primary astrocytomas, grades I and II. The change from astrocytoma grade I to grade III or IV took time longer than that from grade II to grade III or IV. The recurrent time of astrocytomas with different grades showed no statistical differences. Postoperative radiotherapy/chemotherapy did not play a major role in grading changes and recurrent time.